tag:theconversation.com,2011:/global/topics/norovirus-4560/articlesNorovirus – The Conversation2023-12-17T13:41:39Ztag:theconversation.com,2011:article/2192932023-12-17T13:41:39Z2023-12-17T13:41:39ZEnsure a safe and delicious holiday feast: How to use a food thermometer to prevent foodborne illness<figure><img src="https://images.theconversation.com/files/565861/original/file-20231214-23-un4rke.jpg?ixlib=rb-1.1.0&rect=646%2C71%2C5209%2C3916&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Different foods have different target temperatures to eliminate pathogens, so use a reliable food safety chart and a digital food thermometer when cooking each dish, and whenever you reheat leftovers.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><iframe style="width: 100%; height: 100px; border: none; position: relative; z-index: 1;" allowtransparency="" allow="clipboard-read; clipboard-write" src="https://narrations.ad-auris.com/widget/the-conversation-canada/ensure-a-safe-and-delicious-holiday-feast-how-to-use-a-food-thermometer-to-prevent-foodborne-illness" width="100%" height="400"></iframe>
<p>Most holiday festivities include preparing and eating food. Addressing uninvited guests (pathogens) that lurk in the background is crucial amid the joy and celebration. </p>
<p>As food safety researchers, we study how to protect people from infections caused by <a href="https://www.canada.ca/content/dam/hc-sc/healthy-canadians/migration/publications/eating-nutrition/foodborne-illness-infographic-maladies-origine-alimentaire-infographie/alt/pub-eng.pdf">foodborne pathogens</a>. While you likely know to wash your hands and keep your raw meats separate from other foods, there’s another essential thing to do to avoid spending your holiday in the bathroom: probe your food. </p>
<p>Each year, <a href="https://www.canada.ca/en/public-health/services/food-borne-illness-canada/yearly-food-borne-illness-estimates-canada.html">four million Canadians get sick from the food they eat</a>. The most common cause is <a href="https://doi.org/10.1089/fpd.2012.1389">norovirus, which causes the most illnesses</a>. Other leading causes include the bacteria Listeria, Salmonella, Campylobacter and Shiga toxin-producing E. coli.</p>
<p>The impact is far-reaching, from mild cases causing discomfort to severe instances requiring <a href="https://doi.org/10.1017/S0950268810001883">hospitalization</a>. Each year, these infections cause millions of missed workdays, resulting in <a href="https://doi.org/10.1016/j.ijfoodmicro.2008.06.007">productivity losses</a> and costs of <a href="https://doi.org/10.4315/0362-028X-69.3.651">about $400 million</a>. </p>
<p>The <a href="https://www.who.int/groups/foodborne-disease-burden-epidemiology-reference-group-(ferg)">World Health Organization</a> is currently determining how much foodborne illness occurs globally each year, including the long-term complications that can occur, like <a href="https://doi.org/10.1371/journal.pmed.1001921">kidney disease and Guillain Barré syndrome</a>.</p>
<h2>Ensuring food is cooked correctly</h2>
<p>Many people may not know that a <a href="https://publications.gc.ca/Collection/A104-17-2003E.pdf">food thermometer</a> is the only way to know your food is cooked correctly. A food thermometer is your holiday feast’s unsung hero, ensuring that poultry, meats and other dishes — including those that are vegetable-based — reach the internal temperatures needed to eliminate harmful pathogens. </p>
<p>Proper food thermometer use not only safeguards against illness but also enhances the overall culinary experience by guaranteeing that your dishes are cooked to perfection.</p>
<p>But when should you <a href="https://blog.foodsafety.ca/how-use-and-calibrate-probe-thermometer">use a thermometer, and how</a>? You should <a href="https://doi.org/10.4315/0362-028X.JFP-18-245">use your food thermometer any time you cook meat</a> or other foods high in protein (like quiche, stir fry and plant-based “meats”), and whenever you <a href="https://www.canada.ca/en/health-canada/services/general-food-safety-tips/food-safety-tips-leftovers.html">reheat leftovers</a>. </p>
<p>Different foods have different target temperatures, so use a <a href="https://www.canada.ca/en/health-canada/services/general-food-safety-tips/safe-internal-cooking-temperatures.html">reliable food safety chart</a> to determine the appropriate temperature for each dish. If you are pressed for time, the safest temperature for most foods (except whole birds) is <a href="https://www.canada.ca/en/health-canada/services/general-food-safety-tips/safe-internal-cooking-temperatures.html">74 C (165 F)</a>. Health Canada recommends <a href="https://www.canada.ca/en/health-canada/services/general-food-safety-tips/safe-internal-cooking-temperatures.html">82 C (180 F) for whole birds</a> like turkey and chicken. </p>
<p>You can even update your old recipes and cookbooks by changing “cook until the juices run clear” (or other instructions that are not very useful!) to “cook until it reaches 74 (or 82) degrees Celsius.”</p>
<h2>Choosing and using a food thermometer</h2>
<figure class="align-center ">
<img alt="Illustration of a variety of food thermometers" src="https://images.theconversation.com/files/565864/original/file-20231214-27-mflv4p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/565864/original/file-20231214-27-mflv4p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=225&fit=crop&dpr=1 600w, https://images.theconversation.com/files/565864/original/file-20231214-27-mflv4p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=225&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/565864/original/file-20231214-27-mflv4p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=225&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/565864/original/file-20231214-27-mflv4p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=283&fit=crop&dpr=1 754w, https://images.theconversation.com/files/565864/original/file-20231214-27-mflv4p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=283&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/565864/original/file-20231214-27-mflv4p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=283&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Types of food thermometers include instant-read models for quick checks and oven-safe thermometers that you can leave in items while they’re cooking in the oven.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
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</figure>
<p>If you’re among the <a href="https://doi.org/10.4315/JFP-20-148">one-third of Canadians who don’t own a food thermometer</a>, your first step is <a href="https://www.fsis.usda.gov/food-safety/safe-food-handling-and-preparation/food-safety-basics/kitchen-thermometers">selecting the right one</a>. </p>
<p>Choose a reliable digital food thermometer designed for the specific type of food you’re preparing. <a href="https://www.fsis.usda.gov/food-safety/safe-food-handling-and-preparation/food-safety-basics/kitchen-thermometers">There are various types</a>, including instant-read thermometers for quick checks and oven-safe thermometers that you can leave in items while they’re cooking in the oven.</p>
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Read more:
<a href="https://theconversation.com/heres-how-much-your-holiday-dinner-will-cost-this-year-218786">Here's how much your holiday dinner will cost this year</a>
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<p>To <a href="https://www.fsis.usda.gov/food-safety/safe-food-handling-and-preparation/food-safety-basics/kitchen-thermometers">check the temperature</a>, insert the thermometer into the thickest part of the food, avoiding bones and fatty areas. For poultry, the thermometer should be inserted into the innermost part of the thigh and wing and the thickest part of the breast. </p>
<p>Make sure to wait until the temperature readout stops changing, to allow the thermometer sufficient time to provide an accurate reading. Finally, make sure you <a href="https://www.canada.ca/en/health-canada/services/general-food-safety-tips/safe-internal-cooking-temperatures.html#s1">wash the thermometer</a> with warm soapy water after each use. </p>
<h2>Cooked to perfection</h2>
<figure class="align-center ">
<img alt="A roast on a carving board with a meat thermometer in it" src="https://images.theconversation.com/files/565863/original/file-20231214-19-sub7nr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/565863/original/file-20231214-19-sub7nr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/565863/original/file-20231214-19-sub7nr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/565863/original/file-20231214-19-sub7nr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/565863/original/file-20231214-19-sub7nr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/565863/original/file-20231214-19-sub7nr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/565863/original/file-20231214-19-sub7nr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">If a friend cooks the roast beef to sawdust, giving them a meat thermometer can help them cook food to perfection without worrying about pathogens.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<p>Besides making sure food gets hot enough to kill harmful pathogens, there’s other good news about food thermometer use. Does your best friend overcook the roast beef to sawdust level? Do you have a family member who cooks the taste out of chicken in the name of safety? Using a food thermometer <a href="https://blogs.ifas.ufl.edu/seminoleco/2018/02/02/want-your-food-to-taste-better-use-a-thermometer/">can help ensure a moist and delicious meal</a>, bringing friends and family together. </p>
<p>As food safety researchers, our goal is to make sure that “<a href="https://doi.org/10.1111/josh.12782">all Canadians…know how to use a food thermometer, and that it becomes…as much a part of their life as a toothbrush</a>.” On that note, food thermometers make great gifts!</p>
<h2>Handling leftovers</h2>
<p>In addition to using a food thermometer to check that your leftovers are reheated to 74 C before you eat them, there are other important tips for safely handling leftovers this holiday season. </p>
<p><a href="https://www.canada.ca/en/health-canada/services/seasonal-food-safety/holiday-food-safety.html">Refrigerate them promptly in ways that allow them to cool quickly</a>, such as in shallow containers, loosely covered until they are chilled. Either consume them in the next two to three days, or freeze them right away for later use.</p>
<p>Many people prepare unique dishes for the holidays, travel with food and prepared dishes, and host or attend holiday buffets and potlucks. <a href="https://www.canada.ca/en/health-canada/services/seasonal-food-safety/holiday-food-safety.html">Health Canada has specific tips</a> for ensuring your buffets, baked goods, ciders, eggnog, stuffing and more are safe to eat.</p>
<p>Finally, if you do happen to get sick this holiday season with nausea, vomiting, diarrhea or other digestive troubles, make sure you seek health care as needed. From a food safety perspective, the best option, if you can, is to stay out of the kitchen while you are ill and don’t prepare food for others. </p>
<p><em>This article was co-authored by Ken Diplock. He is a professor and program co-ordinator of the Bachelor of Environmental Public Health program at Conestoga College, and a member of the Canadian Institute of Public Health Inspectors.</em></p><img src="https://counter.theconversation.com/content/219293/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Shannon Majowicz has held or currently holds research grants and contracts to study food safety related issues from the Canadian Institutes of Health Research, Bill and Melinda Gates Foundation, World Health Organization, British Columbia Centre for Disease Control Foundation Open Award Program, Public Health Agency of Canada, and the Ontario Ministry of Agriculture, Food, and Rural Affairs' Food Safety Research Fund.</span></em></p>A food thermometer is your holiday feast’s unsung hero, ensuring that poultry, meats and other dishes, including vegetable-based, reach the internal temperatures needed to eliminate harmful pathogens.Shannon Majowicz, Associate Professor, School of Public Health Sciences, University of WaterlooLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2192412023-12-07T17:28:08Z2023-12-07T17:28:08ZThere’s no norovirus outbreak in the UK – so why is a sharp rise in patients being reported?<figure><img src="https://images.theconversation.com/files/564279/original/file-20231207-28-zbjj0b.jpg?ixlib=rb-1.1.0&rect=17%2C17%2C5973%2C3970&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Norovirus causes symptoms such as vomiting, diarrhoea and persistent nausea.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/norovirus-norwalk-virus-called-winter-vomiting-1024674571">Kateryna Kon/ Shutterstock</a></span></figcaption></figure><p>A sharp rise in the number of hospital beds occupied due to <a href="https://www.england.nhs.uk/2023/11/hundreds-of-patients-in-hospital-with-norovirus-ahead-of-winter">patients suffering with norovirus</a> has been reported by the NHS this year. According to the latest NHS <a href="https://www.england.nhs.uk/statistics/statistical-work-areas/uec-sitrep/urgent-and-emergency-care-daily-situation-reports-2023-24/">weekly report</a> on hospital bed occupancy, around 351 people on average were admitted to hospital every day last week with symptoms of diarrhoea and vomiting. During the same period last year, only 126 people were admitted with these symptoms.</p>
<p>But while the NHS is attributing these hospitalisations to norovirus, the numbers don’t suggest the UK is currently facing an outbreak. In fact, the latest data from the <a href="https://www.gov.uk/government/statistics/national-norovirus-and-rotavirus-surveillance-reports-2023-to-2024-season/national-norovirus-and-rotavirus-report-week-49-report-data-up-to-week-47-26-november-2023">UK Health Security Agency</a> (UKHSA) for the same period shows that cases of norovirus aren’t any higher than in previous years.</p>
<p>The common name for norovirus is the “winter vomiting bug” – and as this suggests, the <a href="https://www.nhs.uk/conditions/norovirus/">main symptoms</a> of an infection are vomiting along with diarrhoea and persistent nausea. These symptoms can be accompanied by a high temperature and aches, but this is not as common. </p>
<p>Norovirus symptoms typically last a couple of days and treatment isn’t usually needed. Most patients can manage their symptoms by keeping hydrated and resting. But, in severe cases (especially in children and older adults), dehydration can become an issue and hospitalisation is needed.</p>
<p>But while there’s been an increase in people hospitalised due to diarrhoea and vomiting in recent weeks, that doesn’t necessarily mean we’re facing a norovirus outbreak.</p>
<p>According to the <a href="https://www.gov.uk/government/statistics/national-norovirus-and-rotavirus-surveillance-reports-2023-to-2024-season/national-norovirus-and-rotavirus-report-week-49-report-data-up-to-week-47-26-november-2023">latest report</a> published by the UKHSA, there’s no unusual increase in norovirus cases compared to the previous five years. While their report states that case numbers are up from weeks previous, they’re no higher than compared to previous years. </p>
<p>In fact, the report shows that norovirus cases are 20% lower compared to the previous five-year average for the same two-week period. Hospitalisations for norovirus are also lower this year than they were compared to the same time last year, according to UKHSA data.</p>
<h2>Other possible causes of hospitalisations</h2>
<p>So what might explain the discrepancy between the NHS’s hospitalisation data and the UKHSA’s data on norovirus cases?</p>
<p><a href="https://www.gov.uk/government/statistics/national-norovirus-and-rotavirus-surveillance-reports-2023-to-2024-season/national-norovirus-and-rotavirus-report-week-48-report-data-up-to-week-46-12-november-2023#laboratory-surveillance">Previous data</a> has shown that UK norovirus trends are much more variable than in previous, pre-pandemic, years. More outbreaks are being observed in <a href="https://www.gov.uk/government/news/norovirus-outbreaks-increasing-in-england-1">schools, nurseries and care homes</a>. Unusual peaks are also being seen at unexpected times of the year.</p>
<p>So we could be seeing another unusual peak in norovirus cases, driven by a variety of factors – including some people’s immune systems not being primed to stave off the virus effectively, or changes in protective habits such as less hand washing. </p>
<p>The recent spike in hospitalisations could also indicate that the norovirus strain currently circulating is causing more severe symptoms. </p>
<figure class="align-center ">
<img alt="Sick child laying in hospital bed." src="https://images.theconversation.com/files/564281/original/file-20231207-21-7xs975.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/564281/original/file-20231207-21-7xs975.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=374&fit=crop&dpr=1 600w, https://images.theconversation.com/files/564281/original/file-20231207-21-7xs975.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=374&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/564281/original/file-20231207-21-7xs975.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=374&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/564281/original/file-20231207-21-7xs975.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=470&fit=crop&dpr=1 754w, https://images.theconversation.com/files/564281/original/file-20231207-21-7xs975.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=470&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/564281/original/file-20231207-21-7xs975.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=470&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">There could be a more severe strain spreading currently.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/sick-girl-child-teddy-bear-sleeping-2183698961">WESTOCK PRODUCTIONS/ Shutterstock</a></span>
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<p>It’s important to note as well that the NHS seems to be attributing to norovirus the surge in hospitalisations due to symptoms of vomiting and diarrhoea. While vomiting and diarrhoea certainly are symptoms of norovirus, they aren’t the only reasons a person may experience these symptoms.</p>
<p>Many other viruses and bacteria can cause gastroenteritis (inflammation of the stomach and intestine) such as <a href="https://www.cdc.gov/rotavirus/about/symptoms.html">rotavirus</a> and <a href="https://www.cdc.gov/campylobacter/index.html"><em>Campylobacter</em></a>. </p>
<p>Rotavirus is very contagious and typically causes diarrhoea. Rotavirus case numbers are also reported in the same <a href="https://www.gov.uk/government/statistics/national-norovirus-and-rotavirus-surveillance-reports-2023-to-2024-season/national-norovirus-and-rotavirus-report-week-48-report-data-up-to-week-46-12-november-2023#laboratory-surveillance">UKHSA document</a>. While overall rotavirus numbers are up this year, the most recent weeks have seen these numbers decline again. </p>
<p><em>Campylobacter</em> is a group of bacteria that can cause stomach infections, usually due to <a href="https://www.cdc.gov/campylobacter/faq.html">touching uncooked poultry</a>. While we can see cases all year around, we tend to see more infections in late spring and early summer. </p>
<p>Despite the misleading name of stomach flu, <a href="https://www.niddk.nih.gov/health-information/digestive-diseases/viral-gastroenteritis/symptoms-causes">influenza doesn’t cause</a> diarrhoea and vomiting. In rare cases, <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/jgh.15261">COVID-19 can sometimes cause vomiting</a> – but to have such a change in main symptoms in such a small period would be extraordinary and unlikely. </p>
<p>This complex web of causes, symptoms and hospitalisations makes finding a single cause difficult without more case number data, which will start to come out as the winter season progresses.</p>
<p>No matter the cause of these increased hospitalisations, the root issue is that there’s a much larger burden on the NHS due to admissions with diarrhoea and vomiting. Most pathogens that cause these symptoms are transmitted through touching an infected person, touching surfaces that have the pathogen and then touching your mouth – or eating contaminated food. </p>
<p>We all need to ensure we’re washing our hands regularly when handling food or being around susceptible people, such as children. Extra care is needed in schools, where increases in cases have been seen in previous years. </p>
<p>Of note, alcohol hand gels <a href="https://www.cmaj.ca/content/183/12/E799.short">don’t stop norovirus infections</a>. Only hand washing with soap and hot water can, as this destroys the virus and prevents it from being spread. This practice will also help fight against most other viruses and bacteria.</p><img src="https://counter.theconversation.com/content/219241/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Conor Meehan does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Norovirus, sometimes known as the “winter vomiting bug”, is common this time of year.Conor Meehan, Associate professor of Microbial Bioinformatics, Nottingham Trent UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2178382023-11-21T12:07:28Z2023-11-21T12:07:28ZNo compelling evidence that air purifiers prevent respiratory infections – new study<figure><img src="https://images.theconversation.com/files/560692/original/file-20231121-23-lg1s3r.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C8256%2C4634&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/air-purifier-comfortable-living-room-house-1914045592">Prathankarnpap/Shutterstock</a></span></figcaption></figure><p>The COVID pandemic led to many calls for improved <a href="https://time.com/6143799/covid-19-indoor-air-cleaning/">indoor air quality</a> with claims that doing so would reduce the risk of the <a href="https://www.scientificamerican.com/article/we-need-to-improve-indoor-air-quality-here-rsquo-s-how-and-why/">virus spreading</a>. But the real-world evidence to support these claims has been lacking and studies undertaken during the pandemic have not yet been reported. </p>
<p>So my colleagues and I reviewed the evidence before COVID and found that the balance of evidence was that air treatment does not, in fact, reduce illness from respiratory infections.</p>
<p>There are two main types of air treatment devices: <a href="https://link.springer.com/article/10.1007/s11157-015-9363-9">filters and air disinfectors</a>. Filters work by removing particles from the air that may contain infectious virus. Air disinfectors use ultraviolet radiation or ozone to inactivate viruses in the air.</p>
<p><a href="https://www.sciencedirect.com/science/article/pii/S0091743523003602">In our systematic review</a> we found 32 observational and experimental studies on the topic, conducted between 1970 and 2022. Overall, the evidence was that these technologies did not reduce either the frequency of illness or its severity. </p>
<p>When looking at the laboratory-confirmed influenza or norovirus infections, there was an apparent trend towards fewer infections. However, there was evidence of strong <a href="https://www.jclinepi.com/article/S0895-4356(99)00161-4/pdf">publication bias</a> – which is where significantly positive results are more likely to get published than negative results. </p>
<p>Publication bias makes the apparent impact of any intervention or treatment appear stronger than it is as those negative studies are simply not published.</p>
<p>Our review concluded that there is no strong evidence that air treatment technologies reduce the risks of respiratory transmitted illnesses.</p>
<p>None of the studies included in the review was directly about COVID, as none had been published during the study period. </p>
<p>However, a <a href="https://bmjopen.bmj.com/content/13/7/e072284">recent German study</a> (published in July), did investigate the effect of high-efficiency particulate air (Hepa) filters on COVID in kindergartens. The researchers compared illness rates in schools that had new filters installed with those that did not. </p>
<p>They found that there was no significant difference between the two. Indeed, infection rates were slightly higher in children in those schools that had the filters installed.</p>
<h2>What about ventilation?</h2>
<p>This study did not consider research on the effect of ventilation, such as keeping windows open, on the risk of illness. One possible issue with the studies of air treatment is that ventilation rates may have been reduced, thereby increasing risk. </p>
<p>There has been a recent systematic review of the effect of <a href="https://royalsocietypublishing.org/doi/full/10.1098/rsta.2023.0130">ventilation on COVID infection</a>. Although there was a bit more evidence in support of ventilation reducing infection, the studies were all of poor or very poor quality. As a result, the researchers concluded that the “level of confidence ascribed to this conclusion is low”. </p>
<p>So differences in ventilation are unlikely to explain the negative findings in the air treatment studies.</p>
<figure class="align-center ">
<img alt="A classroom with the window wide open." src="https://images.theconversation.com/files/560702/original/file-20231121-20-kzchb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/560702/original/file-20231121-20-kzchb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/560702/original/file-20231121-20-kzchb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/560702/original/file-20231121-20-kzchb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/560702/original/file-20231121-20-kzchb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/560702/original/file-20231121-20-kzchb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/560702/original/file-20231121-20-kzchb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Ventilation is unlikely to explain the poor performance of air filters.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/table-background-opened-window-schoolbag-view-1467628820">S Photo/Shutterstock</a></span>
</figcaption>
</figure>
<p>If air treatment does not reduce the risk of illness, why may that be the case? I would argue that there are several reasons air treatment technologies were never going to be the <a href="https://theconversation.com/covid-in-schools-how-ventilation-can-help-to-combat-spread-of-virus-165434">panacea</a> that some were <a href="https://www.gov.uk/government/news/more-support-to-keep-pupils-in-the-classroom">claiming</a>.</p>
<p>First, the risk of transmission of respiratory viruses depends on how close you are to an infected person. Early in the pandemic one group of scientists showed that the risk of infection dropped considerably the further <a href="https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(20)31142-9/fulltext#seccestitle10">someone got from an infectious person</a>. </p>
<p>Someone who got within one metre of an infectious person was about five times at greater risk than someone who stayed more than one metre away. It is doubtful that air treatment would affect such close person-to-person transmission.</p>
<p>Second, even if air treatment was effective at preventing infection within a particular indoor space, people move regularly between spaces. Air treatment in your school or workplace will not protect you while on public transport or when gathering in other environments. </p>
<p>Finally, there is the issue of epidemic dynamics of infections that have a short duration of immunity. As I discussed over two years ago, infections like COVID that have a relatively short duration of immunity behave differently than would be predicted by <a href="https://theconversation.com/why-covid-cases-are-now-falling-in-the-uk-and-what-could-happen-next-165123">standard epidemic models</a> because people can be reinfected many times during their life as their immunity wanes. </p>
<p>Infections like COVID are better modelled by the SEIRS (susceptible, exposed, infected, recovered, susceptible) <a href="https://www.nature.com/articles/s41592-020-0856-2">model</a>. In this model, interventions like air filtration or wearing masks become less effective as most infections become reinfections. What then drives infection rates is the rate at which people lose their immunity. </p>
<p>So the balance of real-world evidence is that air treatment technologies do not reduce the risk of becoming ill from a respiratory infection like COVID. There is a little more evidence that increased ventilation may reduce that risk, but the evidence is far from compelling.</p><img src="https://counter.theconversation.com/content/217838/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Paul Hunter consults for the World Health Organization. He receives funding from National Institute for Health Research, the World Health Organization and the European Regional Development Fund.</span></em></p>Air purifiers were meant to save us from COVID. A new systematic review wonders where the evidence for that is.Paul Hunter, Professor of Medicine, University of East AngliaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2175342023-11-14T03:43:40Z2023-11-14T03:43:40ZFrom COVID to gastro, why are cruise ships such hotbeds of infection?<figure><img src="https://images.theconversation.com/files/559213/original/file-20231114-25-qob2l4.jpg?ixlib=rb-1.1.0&rect=12%2C0%2C4228%2C2829&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/large-cruise-ship-front-bow-aerial-2193238525">Kokhanchikov/Shutterstock</a></span></figcaption></figure><p>Dual outbreaks of <a href="https://www.abc.net.au/news/2023-11-12/grand-princess-ship-adelaide-covid-19-gastroenteritis/103095704">gastro and COVID</a> on the Grand Princess cruise ship that docked in Adelaide on Monday <a href="https://www.theguardian.com/australia-news/2023/nov/13/grand-princess-cruise-ship-covid-gastro-outbreak-docks-adelaide-south-australia">have now been declared over</a> by the <a href="https://www.canberratimes.com.au/story/8421009/cruise-ship-doctor-declares-dual-virus-outbreaks-over/">doctor on board</a>.</p>
<p>A spokesperson for Princess Cruises, which operates the ship, said a number of passengers had presented with symptoms <a href="https://www.9news.com.au/national/grand-princess-no-double-covid19-gastro-outbreak-on-ship-cruise-line-says/5d02d423-3289-4a2b-a580-1ed565b78027">on a previous voyage</a>. But the ship has since been disinfected and the number of people who were ill when the ship arrived into Adelaide was said to be in single digits.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1723976819454472401"}"></div></p>
<p>While this is positive news, reports of infectious outbreaks on cruise ships evoke a sense of deja vu. We probably all remember the high-profile COVID outbreaks that occurred on cruise ships in 2020. </p>
<p>So what is it about cruise ships that can make them such hotspots for infection?</p>
<h2>First, what causes these outbreaks?</h2>
<p>Respiratory infectious outbreaks on cruise ships may be caused by <a href="https://wwwnc.cdc.gov/travel/yellowbook/2024/air-land-sea/cruise-ship-travel#">a range of pathogens</a> including SARS-CoV-2 (the virus that causes COVID) and influenza viruses. These can be spread by <a href="https://www.pnas.org/doi/10.1073/pnas.2015482118">respiratory droplets and aerosols</a> released when people breathe, talk, laugh, cough and sneeze.</p>
<p>Historically, <a href="https://jmvh.org/article/the-navy-and-the-1918-19-influenza-pandemic/#">troop transport ships</a> also helped to spread the lethal 1918 flu virus between continents. </p>
<p>Gastro outbreaks on cruise ships are similarly well documented. More than 90% of cruise ship gastro outbreaks are caused by <a href="https://wwwnc.cdc.gov/travel/yellowbook/2024/air-land-sea/cruise-ship-travel#infectious">norovirus</a>, which is spread from person to person, and through contaminated objects or contaminated food or water.</p>
<p>Gastro can also be caused by other pathogens such as <a href="https://wwwnc.cdc.gov/travel/yellowbook/2024/air-land-sea/cruise-ship-travel#">bacteria in contaminated food or water</a>.</p>
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Read more:
<a href="https://theconversation.com/cruise-ships-can-be-floating-petri-dishes-of-gastro-bugs-6-ways-to-stay-healthy-at-sea-this-summer-126351">Cruise ships can be floating petri dishes of gastro bugs. 6 ways to stay healthy at sea this summer</a>
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<h2>What is the risk?</h2>
<p>In 2020, around 19% of <a href="https://www.bmj.com/content/369/bmj.m1632">Diamond Princess</a> passengers and crew docked in Japan tested positive to COVID. Ultimately, nearly one in four <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8739343/">Ruby Princess</a> passengers and crew docked in Sydney tested positive.</p>
<p>However, COVID generally presents a lesser risk nowadays, with most people having some level of immunity from vaccination or previous infection. The outbreak on the Grand Princess appears to have been much smaller in scale.</p>
<p>A <a href="https://www.sciencedirect.com/science/article/abs/pii/S1477893916300680">three-year study</a> before COVID of influenza-like illness (which includes fever), acute respiratory illness (which <a href="https://www.cdc.gov/flu/about/glossary.htm#">doesn’t require fever</a> to be present) and gastro on cruise ships found these were diagnosed in 32.7%, 15.9% and 17% of ill passengers, and 10.9%, 80% and 0.2% of ill crew, respectively.</p>
<p>An <a href="https://www.cdc.gov/mmwr/volumes/70/ss/ss7006a1.htm#">analysis</a> of data from 252 cruise ships entering American ports showed the overall incidence of acute gastro halved between 2006 and 2019. Passenger cases decreased from 32.5 per 100,000 travel days to 16.9, and crew cases from 13.5 per 100,000 travel days to 5.2. This decline may be due to a <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6382806/">combination</a> of improved hygiene and sanitation standards. </p>
<p>The risk of getting sick with gastro was significantly higher on <a href="https://www.cdc.gov/mmwr/volumes/70/ss/ss7006a1.htm#">bigger ships and longer voyages</a>. This is because the longer you are in close contact with others, the greater the chance of exposure to an infectious dose of viruses or bacteria. </p>
<figure class="align-center ">
<img alt="A table with buffet food on a ship." src="https://images.theconversation.com/files/559216/original/file-20231114-15-mipea6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/559216/original/file-20231114-15-mipea6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/559216/original/file-20231114-15-mipea6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/559216/original/file-20231114-15-mipea6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/559216/original/file-20231114-15-mipea6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/559216/original/file-20231114-15-mipea6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/559216/original/file-20231114-15-mipea6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Buffets are one of the factors that can contribute to the risk of infection on a cruise.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/dining-room-buffet-aboard-abstract-luxury-1599780526">Solarisys/Shutterstock</a></span>
</figcaption>
</figure>
<h2>Why are cruise ships infection hotspots?</h2>
<p>On cruise ships, people tend to <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8739343/">crowd together</a> in confined spaces for extended periods. These include dining halls, and during social activities in casinos, bars and theatres. </p>
<p>The risk goes up when the environment is noisy, as more droplets and aerosols are shed when people are <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6382806/">laughing, shouting or talking loudly</a>. </p>
<p>Passengers may come from <a href="https://www.sciencedirect.com/science/article/abs/pii/S1477893916300680?via%3Dihub">multiple countries</a>, potentially bringing variants from different parts of the world. Influenza, which is usually seasonal (late autumn to early spring) onshore, can occur at any time <a href="https://academic.oup.com/cid/article/31/2/433/295546">on a cruise ship</a> if it has international passengers or is calling at international ports. </p>
<p>Human behaviour also contributes to the risk. Some passengers <a href="https://academic.oup.com/jtm/article/15/3/172/1821220">surveyed</a> following cruise ship gastro outbreaks indicated they were ill when they boarded the ship, or they became ill but didn’t disclose this because they didn’t want to pay for a doctor or be made to isolate, or they thought it wasn’t serious.</p>
<p>Those who became ill were more likely than those who did not to think that hand hygiene and isolation were not effective in preventing infection transmission, and were less likely to wash their hands after using the toilet. Given <a href="https://www.health.nsw.gov.au/Infectious/factsheets/Pages/norovirus.aspx#">faecal contamination</a> is a major source of norovirus transmission, this is concerning. </p>
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<strong>
Read more:
<a href="https://theconversation.com/cruise-ships-are-back-and-carrying-covid-no-its-not-2020-but-heres-what-needs-to-happen-next-193384">Cruise ships are back and carrying COVID. No, it’s not 2020. But here’s what needs to happen next</a>
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<p>While there are usually a la carte dining options on board, many people will choose a buffet option. From personal experience, food tongs are handled by multiple people, some of whom may not have cleaned their hands.</p>
<h2>What can help?</h2>
<p>The <a href="https://www.health.gov.au/news/ahppc-statement-advice-to-support-safe-cruising">Department of Health and Aged Care</a> recommends cruise companies encourage crew and passengers to be up-to-date with flu and COVID vaccinations, and encourage anyone who becomes ill to stay in their cabin, or at least avoid crowded spaces and wear a mask in public.</p>
<p>They also recommend cruise ships have a plan to identify and contain any outbreaks, including testing and treatment capacity, and communicate to passengers and crew how they can reduce their transmission risk.</p>
<p>All passengers and crew should report any signs of infectious illness, and practice good hand hygiene and <a href="https://www.cdc.gov/oralhealth/infectioncontrol/faqs/respiratory-hygiene.html">respiratory etiquette</a>, such as covering their mouth if coughing or sneezing, disposing of used tissues, and washing or sanitising hands after touching their mouth or nose. </p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/fleas-to-flu-to-coronavirus-how-death-ships-spread-disease-through-the-ages-137061">Fleas to flu to coronavirus: how 'death ships' spread disease through the ages</a>
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<p>South Australia’s chief health officer has <a href="https://www.abc.net.au/news/2023-11-13/grand-princess-ship-covid-gastro-docks-in-adelaide/103096836">commended</a> the Grand Princess crew for their infection protection and control practices, and for getting the outbreak under control.</p><img src="https://counter.theconversation.com/content/217534/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Thea van de Mortel teaches into the Master of Infection Prevention and Control program at Griffith University. </span></em></p>An expert in infection prevention and control explains.Thea van de Mortel, Professor, Nursing, School of Nursing and Midwifery, Griffith UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1998342023-02-17T06:05:57Z2023-02-17T06:05:57ZNorovirus: what to know about this bug as northern hemisphere countries face outbreaks<figure><img src="https://images.theconversation.com/files/510543/original/file-20230216-26-nix1y9.jpg?ixlib=rb-1.1.0&rect=0%2C9%2C6048%2C4001&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/sad-young-african-american-woman-wearing-1920017237">Vadym Pastukh/Shutterstock</a></span></figcaption></figure><p>Recently there has been a sharp rise in <a href="https://www.gov.uk/government/news/norovirus-cases-increase-significantly-in-england">cases of norovirus</a>, sometimes called the winter vomiting bug, in the UK. </p>
<p>According to the UK Health Security Agency, cases in England are 66% higher than the average for this time of year, and at their highest level in more than a decade. Surveillance data shows norovirus outbreaks have increased in hospitals, schools, and particularly in care homes. The majority of reported cases are in people over 65.</p>
<p>There have also been more norovirus infections reported than usual <a href="https://publichealthscotland.scot/media/17611/laboratoryreportsnorovirusscotlandweek5_2023.pdf">in Scotland</a>, while <a href="https://www.cdc.gov/surveillance/nrevss/norovirus/natl-trend.html">the US</a> and <a href="https://www.cbc.ca/news/health/norovirus-the-culprit-behind-a-nasty-stomach-bug-is-rising-again-in-canada-1.6748246">Canada</a> are similarly recording increasing cases.</p>
<p>So what do you need to know about norovirus?</p>
<p>Norovirus was first identified <a href="https://pubmed.ncbi.nlm.nih.gov/30020637/">in 1968</a> as the cause of an outbreak of gastroenteritis in Norwalk, Ohio. The virus is the <a href="https://www.cdc.gov/norovirus/trends-outbreaks/worldwide.html">most common cause</a> of gastrointestinal symptoms, responsible for about one in five cases of gastroenteritis globally.</p>
<p>Norovirus generally causes nausea, vomiting, diarrhoea and stomach pain. Although in most cases the infection clears in a couple of days, it can take longer. The symptoms can lead to dehydration, sometimes requiring hospitalisation, especially in people with weakened immune systems, older adults and children. </p>
<p>In rare cases, people can die from norovirus. It’s been estimated that <a href="https://pubmed.ncbi.nlm.nih.gov/30584800/">norovirus</a> is responsible for roughly 699 million infections and over 200,000 deaths worldwide each year, with the largest proportion of deaths occurring in children from lower-income countries. Poorer sanitation and access to safe drinking water in developing countries compared with developed countries are <a href="https://pubmed.ncbi.nlm.nih.gov/14987892/">important factors</a>.</p>
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Read more:
<a href="https://theconversation.com/your-blood-type-may-influence-your-vulnerability-to-norovirus-the-winter-vomiting-virus-129125">Your blood type may influence your vulnerability to norovirus, the winter vomiting virus</a>
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<h2>Norovirus is highly contagious</h2>
<p>People with norovirus are <a href="https://www.cdc.gov/norovirus/about/transmission.html">most contagious</a> when they have symptoms, and even during the first few days after they recover. </p>
<p>Norovirus spreads via the faecal-oral route. This means you catch it by accidentally getting <a href="https://www.cdc.gov/norovirus/about/transmission.html">tiny particles</a> from the vomit or faeces of an infected person in your mouth. This might happen, for example, if the virus particles land on surfaces you touch, contaminate the food you eat, or if you have <a href="https://pubmed.ncbi.nlm.nih.gov/30077220/">direct contact</a> with someone who is infected.</p>
<p>Norovirus can also contaminate food if the food is grown or harvested with contaminated water, for example if fruit and vegetable crops are irrigated with contaminated water or if shellfish are harvested from contaminated water (shellfish <a href="https://doh.wa.gov/community-and-environment/shellfish/recreational-shellfish/illnesses/norovirus">can accumulate norovirus</a> in their bodies).</p>
<p>Noroviruses are relatively resistant in the environment. For example, they can survive for long periods on different surfaces, and at high temperatures.</p>
<figure class="align-center ">
<img alt="An illustration of norovirus." src="https://images.theconversation.com/files/510544/original/file-20230216-26-1m7xbe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/510544/original/file-20230216-26-1m7xbe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/510544/original/file-20230216-26-1m7xbe.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/510544/original/file-20230216-26-1m7xbe.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/510544/original/file-20230216-26-1m7xbe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/510544/original/file-20230216-26-1m7xbe.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/510544/original/file-20230216-26-1m7xbe.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Norovirus is a major cause of gastrointestinal illnesses.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/norovirus-norwalk-virus-called-winter-vomiting-1024674571">Kateryna Kon/Shutterstock</a></span>
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<h2>How can you protect yourself against norovirus?</h2>
<p>Unfortunately, there are no approved <a href="https://pubmed.ncbi.nlm.nih.gov/34959596/">vaccines</a> or <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7168425/">antivirals</a> to combat norovirus, despite significant research efforts. Notably, there are many different strains of norovirus, and its genetic diversity makes the development of effective solutions more difficult.</p>
<p>That said, there are some preventive measures you can take to reduce norovirus transmission.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1626160262855200768"}"></div></p>
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<li><p>Wash your hands with soap and water for at least 20 seconds before preparing food, eating and after going to the toilet. Hand sanitisers can be used in addition to hand washing, but hand sanitiser <a href="https://www.cdc.gov/norovirus/about/prevention.html">doesn’t work well</a> against norovirus, so hand sanitiser is not a substitute for washing hands with soap and water.</p></li>
<li><p>Wash fruit and vegetables well. And thoroughly cook shellfish to an internal temperature of <a href="https://www.cdc.gov/norovirus/about/prevention.html">at least 62°C</a> (steam cooking may not heat it enough to kill norovirus).</p></li>
<li><p>If possible, people who are infected should isolate from others until at least <a href="https://www.nhsinform.scot/illnesses-and-conditions/infections-and-poisoning/norovirus">48 hours</a> after their symptoms have passed. They should not be involved in any food preparation.</p></li>
<li><p>If someone in the household has gastrointestinal symptoms, routinely clean surfaces and any objects that are touched, such as kitchen counters, doorknobs and remote controls. Gloves should be worn when cleaning and disinfecting. It’s also advisable to wear a mask if cleaning an infected person’s vomit.</p></li>
<li><p>Thoroughly wash clothes or linen that may be soiled with the vomit or faeces of someone who has been infected. Hot water and detergent should be used for washing at the maximum available cycle length, before machine drying at the highest heat setting.</p></li>
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Read more:
<a href="https://theconversation.com/five-ways-the-pandemic-surge-in-hand-sanitisers-may-not-be-great-news-in-the-long-term-157074">Five ways the pandemic surge in hand sanitisers may not be great news in the long term</a>
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<p>If you do catch norovirus, it’s important to drink plenty of water or electrolyte drinks to prevent dehydration. This is especially true for people who are vulnerable. Fever-reducing medications (such as <a href="https://www.nhsinform.scot/illnesses-and-conditions/infections-and-poisoning/norovirus">paracetamol</a>) and anti-nausea medications may help relieve symptoms. If symptoms become severe or you are concerned, seek medical help.</p><img src="https://counter.theconversation.com/content/199834/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Manal Mohammed does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>If you get sick with norovirus it won’t be pleasant, but will usually pass in a couple of days.Manal Mohammed, Senior Lecturer, Medical Microbiology, University of WestminsterLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1640212021-07-08T11:02:27Z2021-07-08T11:02:27ZWe should treat COVID like norovirus – not the flu<figure><img src="https://images.theconversation.com/files/410301/original/file-20210708-15-1py8yyi.jpg?ixlib=rb-1.1.0&rect=85%2C93%2C4789%2C3101&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/sick-day-home-african-american-woman-1520149034">Photoroyalty/Shutterstock</a></span></figcaption></figure><p>Because COVID symptoms – fever, cough, aches – are similar to <a href="https://www.ecdc.europa.eu/en/seasonal-influenza/facts/factsheet">flu symptoms</a>, it is tempting to compare the two. Indeed, the UK’s new health secretary, Sajid Javid, <a href="https://metro.co.uk/2021/07/05/scientists-slam-sajid-javid-treat-covid-like-flu-comments-14873196/">recently said</a>: “We are going to have to learn to accept the existence of Covid and find ways to cope with it – just as we already do with flu.”</p>
<p>But have we picked the wrong disease to compare COVID-19 with? Outside of a pandemic, we accept that seasonal flu is an infection anyone might catch. We vaccinate only those who are particularly prone to complications and treat people with severe side-effects, such as pneumonia. Otherwise, people are left to go about their business. Global deaths from flu-related illness typically amount to around <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6815659">400,000</a> each year. </p>
<p>While we do need to find some way of living with COVID-19, the numbers suggest we’re still a long way from being able to treat it in the same way. There have been <a href="https://coronavirus.jhu.edu/map.html">over 180 million</a> cases around the world since early 2020, and at least 4 million people have died from the disease. On top of this, we’re not sure of the real effect of <a href="https://www.nhs.uk/conditions/coronavirus-covid-19/long-term-effects-of-coronavirus-long-covid/">long COVID</a> yet, but lasting symptoms are common, with <a href="https://www.euro.who.int/en/about-us/partners/observatory-old/publications/policy-briefs-and-summaries/in-the-wake-of-the-pandemic-preparing-for-long-covid-2021">one in ten people</a> still experiencing illness 12 weeks after their infection. Currently, the health effect of COVID-19 across the population is much greater than flu. </p>
<p>We also know that COVID-19 is more infectious. We can be sure of this because, over the last 18 months, measures to control COVID-19 have reduced flu cases to almost none, but they obviously haven’t been as effective at stopping the coronavirus from spreading. Cases were close to zero in the <a href="https://www.economist.com/graphic-detail/2020/09/12/the-southern-hemisphere-skipped-flu-season-in-2020">southern hemisphere</a> during its winter in the middle of 2020 and again in <a href="https://flunewseurope.org/SeasonOverview">Europe and North America</a> between November 2020 and March 2021. Even in countries with high rates of COVID-19, such as <a href="https://www.washingtonpost.com/world/africa/south-africa-coronavirus-flu-season/2020/08/17/bd8aaaca-e084-11ea-82d8-5e55d47e90ca_story.html">South Africa</a> and the <a href="https://news.sky.com/story/covid-19-lockdowns-and-new-health-habits-help-number-of-flu-sufferers-fall-to-130-year-low-12204516">UK</a>, winter saw hardly any recorded cases of flu.</p>
<figure class="align-center ">
<img alt="A woman walking outside in winter in a mask" src="https://images.theconversation.com/files/410308/original/file-20210708-21-bezuat.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/410308/original/file-20210708-21-bezuat.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/410308/original/file-20210708-21-bezuat.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/410308/original/file-20210708-21-bezuat.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/410308/original/file-20210708-21-bezuat.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/410308/original/file-20210708-21-bezuat.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/410308/original/file-20210708-21-bezuat.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Flu has been all but eradicated over the past 18 months thanks to lockdowns, social distancing and mask wearing.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/london-england-february-2021-beautiful-young-1917559991">Chaz Bharj/Shutterstock</a></span>
</figcaption>
</figure>
<p>All of this suggests that using methods typically used to combat flu will have quite a different effect on COVID-19. Treating COVID-19 like flu will result in many more cases and deaths, and much more lingering illness, than seen in a typical influenza season. </p>
<h2>Another comparison</h2>
<p>Of course, SARS-CoV-2 – the virus that causes COVID-19 – does share some characteristics with influenza viruses, which makes comparisons tempting. <a href="https://www.nature.com/articles/d41586-020-03141-3">Around</a> <a href="https://www.medscape.com/viewarticle/938195">20%</a> of people have no symptoms at all when infected with SARS-CoV-2, and <a href="https://www.cidrap.umn.edu/news-perspective/2014/03/uk-flu-study-many-are-infected-few-are-sick">many people</a> infected with a flu virus also don’t get sick. Both viruses are prone to a lot of mutation. And with both diseases, older people and people with weakened immune systems are at a higher risk of severe illness than healthy young adults, with infections spreading rapidly in care homes, hospital wards and schools.</p>
<p>But a lot of these traits are also shared by another germ: the <a href="https://www.nhs.uk/conditions/norovirus/">norovirus</a>. It too can be <a href="https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1005385">asymptomatic</a> in some people, and mutates rapidly – different strains of norovirus have been found circulating <a href="https://pubmed.ncbi.nlm.nih.gov/21167622/">around the same hospital</a> during one season. In fact, as it spreads around, norovirus sometimes changes so much that standard testing kits <a href="https://journals.asm.org/doi/full/10.1128/JCM.00350-16">can’t recognise</a> versions of it that have evolved.</p>
<p>Most people with symptomatic norovirus infections have diarrhoea, but some experience projectile vomiting as well. This creates an aerosol full of virus that spreads around any room and leaves it on surfaces, waiting for others to pick it up, as happens with respiratory viruses. COVID-19 also <a href="https://covid.joinzoe.com/post/covid-symptoms-diarrhoea">causes diarrhoea</a> in some patients. Flu is not the only viral disease that COVID-19 can be compared to. </p>
<p>Equally, there are a lot of differences between SARS-CoV-2 and norovirus, so why labour the comparison? Well, as vaccines and other control measures get the virus under control, more and more parts of the world will join those others where lockdowns have been lifted, social distancing rules have been relaxed, and it’s safe to leave the house without wearing a mask. But we must still expect outbreaks of COVID-19 for years to come and must have plans to deal with them as they arise.</p>
<figure class="align-center ">
<img alt="Two medical members of staff wearing PPE" src="https://images.theconversation.com/files/410303/original/file-20210708-19-1a7g3vg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/410303/original/file-20210708-19-1a7g3vg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/410303/original/file-20210708-19-1a7g3vg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/410303/original/file-20210708-19-1a7g3vg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/410303/original/file-20210708-19-1a7g3vg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/410303/original/file-20210708-19-1a7g3vg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/410303/original/file-20210708-19-1a7g3vg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Many of the more careful measures used to treat COVID-19 will need to stay.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/covid19-situation-portrait-asian-young-man-1710688690">Pordee_Aomboon/Shutterstock</a></span>
</figcaption>
</figure>
<p>Knowing what we know about these viruses, these plans should consider controlling SARS-CoV-2 more like we would norovirus than flu. With norovirus, we keep people with the infection away from others. We ask parents whose children have symptoms to keep them off school. And in hospitals and care homes, patients with norovirus are nursed separately from others, staff use PPE for protection, and surfaces are deep cleaned. Handling COVID-19 in the future should be more interventionist like this. It should be more akin to living with norovirus than the flu. </p>
<p>In the meantime, we have developed some good hygiene habits during the pandemic, such as washing hands a bit more often and ventilating buildings better. Those who can wear a mask should think about keeping it up in enclosed spaces and on public transport. These simple measures should help to stop the spread of lots of viral diseases – whether against influenza, norovirus or COVID-19 – before bigger interventions are needed.</p><img src="https://counter.theconversation.com/content/164021/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sarah Pitt does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Comparisons with flu are unhelpful – these diseases need to be treated differently.Sarah Pitt, Principal Lecturer, Microbiology and Biomedical Science Practice, Fellow of the Institute of Biomedical Science, University of BrightonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1345662020-04-05T08:34:09Z2020-04-05T08:34:09ZKenya’s slums are a haven for viruses: here’s what we know<figure><img src="https://images.theconversation.com/files/322581/original/file-20200324-155640-l50y4q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">One of Nairobi's low-income areas</span> <span class="attribution"><span class="source">Alex Pix/Shutterstock</span></span></figcaption></figure><p><em>As the new coronavirus spreads in African countries, a big source of concern is how it will spread and affect those that live in congested low-income areas. Moina Spooner from The Conversation Africa asked Eric Fèvre about how viruses spread in Kenya’s low-income areas, and what can be done to prevent it from happening.</em></p>
<p><strong>What viruses are usually found in Nairobi’s low-income settlements and why?</strong></p>
<p>Kenya’s capital, Nairobi, <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6332593/">has more than</a> 40 areas defined as slums and approximately 60% of <a href="https://www.knbs.or.ke/?p=5621">Nairobi’s population</a>, of 4.4 million people, live in low income settlements.</p>
<p>There are many viral infections that cause health problems in these low income settlement environments. This is because they are unplanned, lack sanitation services - like running water or sewerage systems - and their residents are largely poor.</p>
<p>Some of the viruses of most concern are those that cause diarrhoea and pneumonia. Diarrhoea and pneumonia are <a href="https://academic.oup.com/ije/article/44/2/462/752904">the leading</a> cause of death in children under the age of five.</p>
<p>For instance, norovirus - a highly contagious virus that is <a href="https://www.cdc.gov/norovirus/about/transmission.html">usually transmitted</a> through the ingestion of contaminated food and water - is a common cause of diarrhoea. In Kenya’s largest slum, Kibera, a study <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0145943">showed that</a> of 524 people tested for norovirus, 30% were positive. Another study found that <a href="http://europepmc.org/article/PMC/5361529">soil ingestion</a>, by children, is how these diarrheal diseases spread. </p>
<p>Various forms of <a href="https://jim.bmj.com/content/66/6/957">viral pneumonia</a> - a lung infection - are also prevalent in low-income areas. This is because the pathogens that cause it are highly contagious and can spread quickly in environments where people live close together. Families in Kenya’s low-income settlements may also not be <a href="https://www.nation.co.ke/health/pneumonia-still--leading-killer/3476990-4848966-ntbtbp/index.html">able to afford</a> the drugs needed to fight it. </p>
<p>In Kenya, these viruses can have devastating consequences, and mortality rates linked to these infectious diseases <a href="https://www.researchgate.net/publication/260063142_Mortality_Trends_Observed_in_Population-Based_Surveillance_of_an_Urban_Slum_Settlement_Kibera_Kenya_2007-2010">are high</a>. </p>
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<p><strong>From what we know of SARS-CoV-2, are the conditions of Nairobi’s low-income areas conducive to the spread of the virus?</strong></p>
<p>In a word: yes. SARS-CoV2, the virus that causes the COVID 19 disease, spreads because of poor hygiene and close contact. </p>
<p>The <a href="https://www.who.int/emergencies/diseases/novel-coronavirus-2019/advice-for-public">global message</a> about reducing the risk of spread is to increase personal hygiene, especially regular hand washing, to keep physical distance from other, potentially infected people and therefore reduce the density of people in any one place (including “working from home”), and to avoid touching potentially contaminated surfaces especially in public places, given that the virus can stay viable for up to 72 hours (3 days) on some kinds of material.</p>
<p>But many of these avoidance mechanisms are difficult to enact in low-income areas. Average household size <a href="http://documents.worldbank.org/curated/en/450081468047364801/pdf/363470KE.pdf">is between</a> three to four people, though there are cases <a href="https://www.kibera.org.uk/Reports/Nairobi%20Slum%20Survey%202012.pdf">where</a> 10 people might live in a small informal structure with no windows. There is no piped water and soap may be a luxury expense. </p>
<p>A subsistence daily wage is often earned by travelling long distances to a job. And people rely on that daily wage for their <a href="https://doi.org/10.1007/s11524-014-9894-3">daily meals</a>. </p>
<p><strong>How can residents of these areas minimise their risk to SARS-CoV-2?</strong></p>
<p>Vaccines are usually the main way that the risk of a virus can be minimised. Common viral diseases, including chicken pox and measles, would have spread rapidly in close-knit populations were it not for extensive state sponsored vaccination campaigns to keep people safe. There is a race to create the COVID-19 vaccine, but this <a href="https://www.theguardian.com/world/2020/mar/31/coronavirus-vaccine-when-will-it-be-ready">will take</a> a long time. </p>
<p>To minimise their risk to the virus - challenging as it might be - residents should, like residents everywhere, be practising as much personal hygiene as they can. For instance, wash hands whenever possible. The community and local government can and <a href="https://reliefweb.int/report/kenya/water-handwashing-slums-critical-prevent-covid-19-spreading">are helping with this</a>, and I understand that water distribution points for hand-washing are <a href="https://unhabitat.org/kenyan-youth-wash-hands-to-keep-away-covid-19-in-informal-settlement">being set up</a> as a public service. </p>
<p>The community must also unify, alerting each other where necessary of illness resembling COVID-19, and self-isolate (if possible) in the case of a potential exposure. </p>
<p>Most importantly, no one is to blame for the spread of the virus, and there should not be a pattern of blaming others. Each individual should take responsibility for themselves. </p>
<p>In short, these are the same recommendations as everywhere else in the world right now, within what circumstances allow. Government public health authorities are doing what they can, and people should listen to and follow their advice.</p>
<p>The added challenge for residents during this pandemic are the diseases and health conditions that already exist, and which could predispose people to worse outcomes if infected with COVID-19. </p>
<p>These include respiratory bacterial infections, such as <a href="https://www.ajol.info/index.php/eamj/article/view/172068">tuberculosis</a> and chronic disease <a href="https://doi.org/10.1186/s40795-016-0086-2">related to</a> nutrition and poor health. We don’t know for sure what the interactions are between COVID and other diseases, but <a href="https://www.thelancet.com/journals/lanres/article/PIIS2213-2600(20)30151-X/fulltext">it is likely</a> that there will be interactions. </p>
<p><strong>What steps should the government take to help mitigate these risks?</strong></p>
<p>The government is helping by providing easier access to water and sanitation. It should also make plans to ease the routes of food supply. People will become more susceptible if they’re starving. Food distribution systems in these environments follow largely informal channels through markets and selling on the streets. These channels <a href="https://doi.org/10.1016/j.agsy.2018.08.007">work well</a>. But they are also vulnerable, especially as movement and transport links get disrupted. And when markets are being closed down, as is the case now.</p>
<p>The authorities must allow supply chains to operate and continue to move the essential food commodities – such as milk, meat and vegetables – that people need. </p>
<p>Finally, the government should be open about its mitigation strategies, and provide clear information to allay the fears of the population.</p><img src="https://counter.theconversation.com/content/134566/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Eric Fèvre receives funding from The UK Medical Research Council, the UK Biotechnology and Biological Sciences Research Council, the CGIAR Research Program on Agriculture for Nutrition and Health and the EU European and Developing Countries Clinical Trials Partnership. </span></em></p>Because low-income settlements are unplanned, crowded and without sanitation, there are many viral infections that cause health problems.Eric Fèvre, Professor of Veterinary Infectious Diseases, University of Liverpool and International Livestock Research Institute, Kenya, University of LiverpoolLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1343072020-03-25T12:29:42Z2020-03-25T12:29:42ZCalling COVID-19 a ‘Chinese virus’ is wrong and dangerous – the pandemic is global<figure><img src="https://images.theconversation.com/files/322745/original/file-20200324-155631-1vurwux.jpg?ixlib=rb-1.1.0&rect=174%2C0%2C4304%2C3102&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">U.S. officials risk public health by equating COVID-19 with places far from home.</span> <span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Virus-Outbreak-Trump/4c902df8cb0f4b2a9a26ccd83cc633a3/2/0">AP Photo/Patrick Semansky</a></span></figcaption></figure><p>The COVID-19 pandemic has spread to <a href="https://gisanddata.maps.arcgis.com/apps/opsdashboard/index.html#/bda7594740fd40299423467b48e9ecf6">almost every country on Earth</a>. And yet, <a href="https://twitter.com/DrPaulGosar/status/1236821135964004352">several</a> <a href="https://twitter.com/realDonaldTrump/status/1240226752447873027">American officials</a> refer to it as the “<a href="https://www.cnbc.com/2020/03/06/secretary-of-state-mike-pompeo-says-china-not-forthcoming-initially-on-coronavirus-setting-prevention-efforts-back.html">Wuhan virus</a>” or even the “<a href="https://twitter.com/jabinbotsford/status/1240701140141879298">Chinese virus</a>.”</p>
<p>U.S.-Chinese antagonism in this vein is <a href="https://www.politico.com/magazine/story/2019/10/15/donald-trump-china-trade-war-hostility-229851">not new</a>. But, while this deliberate move to associate Wuhan, and more generally China, with the COVID pandemic <a href="https://slate.com/news-and-politics/2020/03/trump-calling-coronavirus-chinese-virus.html">serves a political purpose</a> <a href="https://www.nytimes.com/2020/03/18/us/politics/china-virus.html">for the Trump administration</a>, it also has significant implications for civil society and public health.</p>
<p>As a <a href="https://www.history.pitt.edu/people/mari-webel">historian of public health and modern Africa</a>, I study the politics of infectious diseases and responses to them. In addition to inflaming racism, emphasizing the foreign or external origins of a disease influences how people understand their own risk of disease and whether they change their behavior.</p>
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<h2>WHO guidelines are clear</h2>
<p>While identifying a new disease by its place of origin seems intuitive, history demonstrates that doing so can harm the people who live there.</p>
<p><a href="http://thenationshealth.aphapublications.org/content/45/6/1.1">Consequences can include</a> economic distress, as tourists withdraw, investment cools down and solidarity between people weakens. Linking a specific disease with a specific place can lead to <a href="https://www.questia.com/library/journal/1G1-195680111/the-yellow-peril-revisited-the-impact-of-sars-on">discrimination</a>, <a href="https://doi.org/10.1353/ces.2008.0002">stigmatization</a> and <a href="https://www.discovermagazine.com/health/death-at-the-corners">avoidance of a town or village</a>.</p>
<p>For all these reasons, in 2015, the World Health Organization established <a href="https://apps.who.int/iris/bitstream/handle/10665/163636/WHO_HSE_FOS_15.1_eng.pdf?sequence=1">a new set of best practices</a> for naming diseases. The WHO sought to <a href="https://www.who.int/mediacentre/news/notes/2015/naming-new-diseases/en/">abandon associating places with a disease</a> – as was the case with COVID-19’s cousin, MERS (Middle East respiratory syndrome) in 2012, and many others in the past.</p>
<p>So on Feb. 11, the WHO recommended <a href="https://www.who.int/dg/speeches/detail/who-director-general-s-remarks-at-the-media-briefing-on-2019-ncov-on-11-february-2020">using the name COVID-19</a> when referring to the novel coronavirus that was, at the time, sickening and killing people in central China and elsewhere in eastern Asia. Other experts concurred, but differentiated between the <a href="https://www.nature.com/articles/s41564-020-0695-z">virus that causes the disease</a>, known as SARS-CoV-2, and the disease itself, COVID-19.</p>
<p>The name reflects the pathogen (a coronavirus, COV), the nature of the illness caused (an infectious disease) and its year of origin (2019).</p>
<h2>A long tradition of naming by place</h2>
<p>Tagging a place when identifying a disease has a long history. </p>
<p>In the 19th century, as global trade and mobility allowed cholera to spread worldwide from its origins in the Ganges Delta, the disease quickly became known as “the Asiatic cholera.” <a href="https://www.amazon.com/Cholera-Biography-Biographies-Christopher-Hamlin/dp/019954624X">That label persisted for decades</a>, implicitly blaming an entire continent for a disease that can spread anywhere as a function of poor sanitation.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/315567/original/file-20200215-11000-4knczk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/315567/original/file-20200215-11000-4knczk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/315567/original/file-20200215-11000-4knczk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=475&fit=crop&dpr=1 600w, https://images.theconversation.com/files/315567/original/file-20200215-11000-4knczk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=475&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/315567/original/file-20200215-11000-4knczk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=475&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/315567/original/file-20200215-11000-4knczk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=596&fit=crop&dpr=1 754w, https://images.theconversation.com/files/315567/original/file-20200215-11000-4knczk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=596&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/315567/original/file-20200215-11000-4knczk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=596&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">During an 1884 cholera epidemic in France, public health workers disinfect baggage at a quarantine station for maritime travelers.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/cholera-epidemic-france-1884-public-health-242815612">Everett Historical/Shutterstock.com</a></span>
</figcaption>
</figure>
<p>For Europeans and Americans of the time, Asia was an exotic, distant somewhere else. Distinguishing the disastrous illness of cholera as “Asiatic” fit with the racialized, imperial views that denigrated the intelligence and the cultures of non-white populations globally. It also helped justify more stringent <a href="https://doi.org/10.1017/S0018246X06005280">quarantine measures and travel restrictions</a> for people read as “Asian” and not European. <a href="https://doi.org/10.1017/S0020743808080549">Muslim pilgrims en route to Mecca</a> from southern Asia, for instance, were <a href="https://doi.org/10.1017/S0010417515000407">subject to different rules</a> than European troop ships traveling the same routes. </p>
<p><a href="https://www.cambridge.org/us/academic/subjects/history/history-medicine/laboratory-revolution-medicine?format=PB">Ideas about disease changed</a> after the late 19th century, when scientists could use new laboratory techniques to link specific pathogens – bacteria, parasites and, later on, viruses – to specific diseases. Sometimes, this gave a scientific name to an age-old problem, such as “consumption” becoming the medical entity tuberculosis.</p>
<p>But these new techniques also allowed researchers to correlate pathogens with particular locales. Naming an illness after a place quickly became the norm.</p>
<p>So <a href="https://www.cdc.gov/vhf/rvf/index.html">Rift Valley Fever</a>, caused by a virus in the <em>Bunyaviridae</em> family, got its name from an area of colonial Kenya where it was first reported.</p>
<p>The <a href="https://www.cdc.gov/hantavirus/index.html">Hantaviruses</a> are linked to the Hantan River area of South Korea where <a href="https://doi.org/10.1086/424604">Dr. Ho-Wang Lee first identified the virus</a>.</p>
<p><a href="https://www.cdc.gov/vhf/ebola/index.html">Ebola virus disease</a> got its popular name from a river near the village in the modern nation of Democratic Republic of Congo where U.S. and European scientists <a href="https://doi.org/10.1093/infdis/jiw207">identified that pathogen</a>. Scientists <a href="https://www.statnews.com/2016/07/14/history-ebola-peter-piot/">chose that name deliberately</a>, trying to avoid saddling any one village with being the point of origin for the hemorrhagic fever.</p>
<p>Focusing on a specific place creates something particular from something that could have happened anywhere. There’s nothing peculiarly distinctive about Lassa village in Nigeria, compared to any other village five or 50 miles away. Lassa was <a href="https://doi.org/10.4269/ajtmh.2012.12-0466">just the first place</a> where a white missionary’s death drew the attention of authorities. And yet, in the aftermath of that moment, as “<a href="https://www.cdc.gov/vhf/lassa/index.html">Lassa fever</a>” came to identify a fearsome hemorrhagic fever, the town of <a href="https://nigeriahealthwatch.com/how-lassa-went-from-a-small-nigerian-town-to-a-well-known-virus/#.XkbVLhd7kSd">Lassa became a shadow of its former self</a>.</p>
<p>Likewise <a href="https://www.chicagotribune.com/news/ct-xpm-2002-12-17-0212170281-story.html">Norwalk, Ohio, still deals with its association with noroviruses</a>, first identified from a 1968 outbreak in the small Midwestern town. One of the Norwalk-type viruses causes an acute stomach bug that was <a href="https://doi.org/10.1155/2003/702517">historically known as the “winter vomiting disease”</a> and still causes widespread illness today.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/315568/original/file-20200215-10985-5ziaaj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/315568/original/file-20200215-10985-5ziaaj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/315568/original/file-20200215-10985-5ziaaj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=419&fit=crop&dpr=1 600w, https://images.theconversation.com/files/315568/original/file-20200215-10985-5ziaaj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=419&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/315568/original/file-20200215-10985-5ziaaj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=419&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/315568/original/file-20200215-10985-5ziaaj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=526&fit=crop&dpr=1 754w, https://images.theconversation.com/files/315568/original/file-20200215-10985-5ziaaj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=526&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/315568/original/file-20200215-10985-5ziaaj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=526&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Ebola virus disease outbreak was more about public health infrastructure than people’s lifestyles.</span>
<span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Mali-Ebola-/7f37ac37eb804adbaf11efa628eb8ec1/2/0">AP Photo/Baba Ahmed</a></span>
</figcaption>
</figure>
<h2>Building blame into a name</h2>
<p>Insisting on emphasizing COVID-19’s origins within China, even though the disease is now global, <a href="https://nplusonemag.com/online-only/online-only/chinese-virus-world-market/">plays into racist stereotypes</a>, including about culture and food.</p>
<p>Similar stereotypes arose, for instance, around Ebola virus disease (EVD) in 2014-15, erroneously blaming people in West Africa for the wider epidemic.</p>
<p>Early conversations about EVD, marked as particularly African with its name, focused on eating “bushmeat,” a term from the colonial era to describe meat from hunted animals, rather than from domesticated animals. Talking about “bushmeat” allowed people to characterize those suffering from EVD as <a href="https://www.washingtonpost.com/news/monkey-cage/wp/2014/08/25/othering-ebola-and-the-history-and-politics-of-pointing-at-immigrants-as-potential-disease-vectors/">primitive or exotic</a>. It also implied that West Africans were responsible for bringing EVD into global circulation because of what they ate or how they lived.</p>
<p>In fact, the <a href="https://doi.org/10.1017/asr.2015.11">wider spread of EVD in 2014-15</a> beyond the rural hinterlands of Guinea had everything to do with <a href="https://doi.org/10.1093/afraf/adu080">underfunded health systems in the affected nations</a> and little to do with what people ate.</p>
<p>A similar process unfolded with assertions that a “wet market” in Wuhan was the culprit of zoonotic spillover that resulted in COVID-19. Scientists don’t yet know how relevant Wuhan’s live-animal markets were for this global epidemic, although they do know that <a href="https://doi.org/10.1371/journal.ppat.1006215">viruses jump from animals to humans</a>, and back again, frequently.</p>
<p><a href="https://www.sciencemag.org/news/2020/01/wuhan-seafood-market-may-not-be-source-novel-virus-spreading-globally">Recent research suggests</a> that one of Wuhan’s “wet markets” was relevant for human-to-human transmission, as a place of close contact, rather than a space of human-animal contact. Ultimately, Wuhan’s historic position as a <a href="https://doi.org/10.3390/ijgi7080320">national high-speed rail</a> and commercial hub is likely to be far more important for the wider dissemination of COVID-19 than where and how people shopped and ate. </p>
<h2>Focusing on the wrong things</h2>
<p>Understanding disease ecology and patterns of transmission at a point of origin are important for biologists and epidemiologists. But persistently linking a disease to a specific place - particularly when other consensus terms exist - serves to keep public attention on the outbreak’s first spillover moment.</p>
<p>This focus on how an <a href="https://dx.doi.org/10.3201/eid0204.960402">emerging disease</a> originally reached human populations sends a mixed message about who is at risk of infection or how to prevent the disease in an ongoing epidemic. This is exactly the situation playing out in the United States right now.</p>
<p>Once a disease has started circulating in human populations, its point of origin is far less relevant for a general public looking to stay healthy or public health practitioners trying to control a person-to-person epidemic than, for instance, good hand and respiratory hygiene or access to medical care.</p>
<p>Further, tagging China or Wuhan amid this global pandemic undermines a sense of mutual responsibility and fundamental human connectivity, values that are vital amid this human crisis.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/322748/original/file-20200324-155702-idqz8l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/322748/original/file-20200324-155702-idqz8l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/322748/original/file-20200324-155702-idqz8l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/322748/original/file-20200324-155702-idqz8l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/322748/original/file-20200324-155702-idqz8l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/322748/original/file-20200324-155702-idqz8l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/322748/original/file-20200324-155702-idqz8l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/322748/original/file-20200324-155702-idqz8l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A focus on the ‘foreignness’ of a virus can cause people to underestimate their own risk and ignore public health messages.</span>
<span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Virus-Outbreak-New-York/4c2a826fe7b64f178c6cc0c16f3c3c23/1/0">AP Photo/John Minchillo</a></span>
</figcaption>
</figure>
<p>By focusing on the novel coronavirus’s emergence in a place exotic to many Americans, U.S. officials are emphasizing the disease’s past origins rather than its present danger. Playing up the “<a href="https://www.nytimes.com/2020/03/11/us/politics/trump-coronavirus-speech.html">foreign</a>” origins of COVID-19 in Wuhan and China allows governments to lay blame. But it also allows people to justify a lack of caution – it’s a problem from “over there,” not one that “we” are making worse – rather than undertake the everyday measures needed to slow down the spread of disease. </p>
<p>Calling COVID-19 the “Wuhan virus” or the “Chinese virus” is absurd when it has spread globally. Intentionally referring to COVID-19 as a “Chinese virus” only <a href="https://www.nytimes.com/2020/03/23/us/chinese-coronavirus-racist-attacks.html?fbclid=IwAR2MVPNwXG0yaZBXTuGPgWY5mNGVr0hgU65SEE665eD3JP7_Pj3QD6wkK28">inflames animosity</a> and hinders the real work of public health and disease prevention.</p>
<p><em>This is an updated version of an <a href="https://theconversation.com/naming-the-new-coronavirus-why-taking-wuhan-out-of-the-picture-matters-131738">article originally published</a> on Feb. 18, 2020.</em></p><img src="https://counter.theconversation.com/content/134307/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mari Webel does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Emphasizing foreign origins of a disease can have racist connotations and implications for how people understand their own risk of disease.Mari Webel, Assistant Professor of History, University of PittsburghLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1330542020-03-17T19:46:25Z2020-03-17T19:46:25ZViruses live on doorknobs and phones and can get you sick – smart cleaning and good habits can help protect you<figure><img src="https://images.theconversation.com/files/320286/original/file-20200312-111300-zgdow6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Disinfecting an area takes time and effort. And there is only so much you can do. </span> <span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Virus-Outbreak-New-York/4af925c106ca40268d5db383657b355e/2/0">AP Photo/Seth Wenig</a></span></figcaption></figure><p>One vomiting episode from someone infected with norovirus <a href="https://dx.doi.org/10.3201/eid1410.080117">emits billions and billions of individual viruses</a>. That’s enough to fuel an outbreak – and is exactly what happened in an elementary school in <a href="https://www.usatoday.com/story/news/health/2019/12/13/norovirus-outbreak-stomach-flu-terrorizes-washington-public-schools/4417867002/">Seattle, Washington a few months ago</a>. Over 100 children got sick with the stomach-churning bug, and the school doors remained closed until workers could decontaminate the lockers, desks and hallways.</p>
<p>You might think of germs mostly passing directly from one person to another, but the outbreak in Seattle illustrates how they can survive on and be transmitted by inanimate objects in the world around us. <a href="https://sph.umich.edu/faculty-profiles/eisenberg-joseph.html">Epidemiologists like me</a> call these everyday objects – like doorknobs, elevator buttons and cellphones – fomites, and when contaminated, these fomites can make you sick. </p>
<p>Fomites can be an important pathway of disease transmission. They were the main culprits in that norovirus outbreak in Seattle last year and have been the cause of many other outbreaks. In 1908, <a href="https://dx.doi.org/10.1128%2FAEM.02051-06">smallpox outbreaks were traced to contaminated imported cotton</a>. More recently, <a href="https://doi.org/10.1093/oxfordjournals.aje.a113661">outbreak studies in day care centers</a> have identified viruses on <a href="https://www.ncbi.nlm.nih.gov/pubmed/8393172">toys, phones, toilet handles, sinks and water fountains</a>.</p>
<h2>The novel coronavirus</h2>
<p>The coronavirus is spreading quickly. As concern has increased, I’ve seen more people washing their hands and using hand sanitizer than ever before. While there is still a lot we don’t know about the new coronavirus, SARS-CoV-2, history would suggest that there is probably some transmission from fomites. Everyone should be washing their hands and using hand sanitzer, but taking efforts to clean the things around you is also important to fight the spread of the virus.</p>
<p>For instance, in the last major coronavirus pandemic, SARS in 2002, contaminated surfaces were a major contributor to over <a href="https://dx.doi.org/10.1258%2Fjrsm.96.8.374">300 cases in a Hong Kong apartment building</a>.</p>
<p>When thinking about how risky transmission via fomites is in an outbreak, the important question is how long can a particular bug survive on surfaces. And there is a lot of variation. Some pathogens can last outside the body for only minutes, while others are hardier and can hold on for days or even months. A new study suggests that the novel coronavirus <a href="https://doi.org/10.1101/2020.03.09.20033217">can survive on some surfaces up to three days</a>, but it varies depending on the material. The study found that the virus could survive for 24 hours on cardboard and up to three days on plastic and stainless steel.</p>
<p>This variation is caused in part by the <a href="https://doi.org/10.1186/1471-2334-6-130">properties of the surface a virus lands on</a>. Porous material like clothing may allow pathogens to survive longer but it can be harder for a virus to move <a href="https://doi.org/10.1128/AEM.01030-13">from your shirt to someone else’s fingers</a>. The matrix fibers in nonporous materials can trap germs making it hard for them to transfer. On the other hand, viruses can more readily transfer from nonporous materials like the glass screen on your phone to fingers, but the virus won’t always survive as long on a glass surface compared to a sweater.</p>
<p>Environmental conditions such as <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC201876/">temperature and humidity also influence the viability of a pathogen in the environment</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/320291/original/file-20200312-111268-3h808r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/320291/original/file-20200312-111268-3h808r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/320291/original/file-20200312-111268-3h808r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/320291/original/file-20200312-111268-3h808r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/320291/original/file-20200312-111268-3h808r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/320291/original/file-20200312-111268-3h808r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/320291/original/file-20200312-111268-3h808r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/320291/original/file-20200312-111268-3h808r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Most viruses will eventually die on their own. But cleaning with alcohol, bleach and other chemicals can kill them more quickly.</span>
<span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Ukraine-Virus-Outbreak/6b99329a97094a578d3b689b6f5d9924/20/0">AP Photo/Efrem Lukatsky</a></span>
</figcaption>
</figure>
<h2>Persistent bugs and how to get rid of them</h2>
<p>It’s nearly impossible to keep anything in the real world virus-free, but during outbreaks like this one it’s a good idea to try to minimize the number of viruses on fomites around you. Some people are practically bathing in hand sanitizer and wiping down everything they touch with disinfectant. But whether this works depends on what virus you are hoping to kill.</p>
<p>Norovirus, for example, is notoriously hardy. After an outbreak on a cruise ship in 2002, the next group of passengers got sick <a href="https://dx.doi.org/10.3201%2Feid1101.040434">more than a week later after a thorough cleaning of the ship</a>. Many standard cleaners like alcohol or Lysol do not kill norovirus. It takes something as strong as chlorine bleach to get the job done. </p>
<p>In contrast to norovirus, <a href="https://dx.doi.org/10.1128%2FAEM.02051-06">influenza is much less persistent in the environment</a>. While influenza is often lurking in daycare centers during flu season, it typically lasts on surfaces only for hours or a few days. And if you wanted to clean off your phone or countertop, simply wiping it down with an alcohol-based product or ammonia is effective.</p>
<p>While virologists don’t know much about how tough the current coronavirus is, past coronaviruses have fallen somewhere between norovirus and the flu. Like influenza, Lysol will likely kill the coronavirus.</p>
<p>But you don’t necessarily need to kill the virus to make yourself safer. Removing the virus can be just as effective and simply <a href="https://www.cdc.gov/handwashing/show-me-the-science-hand-sanitizer.html">washing often-used objects or your hands with soap can do that</a>.</p>
<p>If you have been in crowded areas or want to be extra careful, washing your hands with soap for 20 seconds will effectively remove germs, and disinfecting tabletops and gym equipment with ammonia will effectively kill most germs.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/320289/original/file-20200312-111237-38wj0i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/320289/original/file-20200312-111237-38wj0i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/320289/original/file-20200312-111237-38wj0i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/320289/original/file-20200312-111237-38wj0i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/320289/original/file-20200312-111237-38wj0i.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/320289/original/file-20200312-111237-38wj0i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/320289/original/file-20200312-111237-38wj0i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/320289/original/file-20200312-111237-38wj0i.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Viruses are on everything. How you behave around them matters.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/asian-woman-with-protective-face-mask-using-royalty-free-image/1203348066?adppopup=true">d3sign/Moment via Getty Images</a></span>
</figcaption>
</figure>
<h2>What can you do in a world with viruses everywhere?</h2>
<p>During the coronavirus pandemic, it is important to clean the objects you touch frequently, like keyboards, tabletops and gym equipment.</p>
<p>But while fomites are known to be the culprits in many outbreaks, an individual’s risk depends on a lot of factors. Someone who touches contaminated surfaces frequently, like a health care worker, <a href="https://www.nytimes.com/interactive/2020/03/15/business/economy/coronavirus-worker-risk.html">is more likely to get sick than someone who doesn’t</a>. Risk also depends on personal habits, such as how often one touches their eyes, nose and mouth. And for most infectious diseases, whether someone gets sick and the severity of the illness depends on age and underlying health conditions.</p>
<p>Cleaning objects frequently with a disinfectant is the best way to mitigate the risk of transmission from everyday objects. Hand-washing is also important, especially if done reliably right after coming home from a public place.</p>
<p>Given that germs are ubiquitous, it’s easy to become germ-phobic and strive for a sterile environment. But keep in mind that while basic precautions are important, germs will always find a way to exploit our human environment. You can and should minimize risk, but germs are here to stay. </p>
<p>[<em>You’re smart and curious about the world. So are The Conversation’s authors and editors.</em> <a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=youresmart">You can read us daily by subscribing to our newsletter</a>.]</p><img src="https://counter.theconversation.com/content/133054/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Joseph Eisenberg does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The coronavirus, like many infectious diseases, can live and spread on inanimate objects in the world around us. An epidemiologist explains how and gives some advice on how to minimize the risk.Joseph Eisenberg, Professor and Chair of Epidemiology, University of MichiganLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1291252020-01-10T13:44:25Z2020-01-10T13:44:25ZYour blood type may influence your vulnerability to norovirus, the winter vomiting virus<figure><img src="https://images.theconversation.com/files/308691/original/file-20200106-123411-1f6nutm.jpg?ixlib=rb-1.1.0&rect=43%2C96%2C5769%2C3796&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Projectile vomiting is common with norovirus.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/man-suffering-sick-stomach-vomiting-674213719">Elnur/Shutterstock.com</a></span></figcaption></figure><p>In the last few months, schools all over the country have closed because of outbreaks of norovirus. Also known as <a href="https://www.cdc.gov/norovirus/about/index.html">stomach flu</a>, norovirus infections cause watery diarrhea, low-grade fever and, most alarming of all, projectile vomiting, which is an extremely effective way of <a href="https://doi.org/10.1371/journal.pone.0143759">spreading the virus</a>.</p>
<p>Norovirus is very infectious and spreads rapidly through a confined population, such as at a school or on a cruise ship. Although most sufferers recover in 24 to 48 hours, norovirus is a leading cause of childhood illness and, in developing countries, results in about <a href="https://www.cdc.gov/norovirus/trends-outbreaks/worldwide.html">50,000 child deaths each year</a>. </p>
<p>Interestingly, not everyone is equally vulnerable to the virus, and whether you get sick or not <a href="https://doi.org/10.3390/v11030226">may depend on your blood type</a>. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/308462/original/file-20200103-11909-1c1i1uc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/308462/original/file-20200103-11909-1c1i1uc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/308462/original/file-20200103-11909-1c1i1uc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=397&fit=crop&dpr=1 600w, https://images.theconversation.com/files/308462/original/file-20200103-11909-1c1i1uc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=397&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/308462/original/file-20200103-11909-1c1i1uc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=397&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/308462/original/file-20200103-11909-1c1i1uc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=499&fit=crop&dpr=1 754w, https://images.theconversation.com/files/308462/original/file-20200103-11909-1c1i1uc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=499&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/308462/original/file-20200103-11909-1c1i1uc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=499&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">3D print of Norwalk virus, a type of norovirus. Noroviruses are the most common cause of acute gastroenteritis (infection of the stomach and intestines) in the United States.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/niaid/14550066332/in/photolist-oaJTNC-9kN9fS-zT8zR-zRqum-7JT92b-2fHvpyV-nPdK6g-4nS4tN-bkSbTa-9iHCcg-zRqqG-4dHSzJ-dT7574-ehXMFj-mvhVYa-4BWSQk-fjrZgr-zRqrj-5suMaZ-GdQtN9-FPgYQG-dUtuUb-dMVx4Y-R2HhVV-kc9sdG-e4ZuwX-BhXmt-bBSVNr-2g7RMr6-R2agqV-Qg6WSu-2g7S1zi-7n7421-ehRTcF-dPNyUq-dPGX22-yF16XT-dKeb3j-pBZyB5-dPGXwn-fox1yW-dPGA68-4QTPtv-8i7Pxd-6N6awr-d6BGam-jCdHzU-byxjM8-dQS3gV-dQqL4r">NIH</a></span>
</figcaption>
</figure>
<h2>Norovirus is hard to get rid of</h2>
<p><a href="https://biology.indiana.edu/about/faculty/foster-patricia.html">I am a microbiologist</a>, and I got interested in norovirus because, while norovirus symptoms are distressing under any circumstances, my encounter with the virus was particularly inconvenient. During a seven-day rafting trip down the Grand Canyon, the illness passed through the rafters and crew, one by one. Obviously, the wilderness sanitary facilities were not the best to cope with this outbreak. Luckily, everyone, including me, recovered quickly. It turns out that <a href="https://azdailysun.com/news/local/norovirus-back-in-canyon/article_cd739e60-ea66-5d94-9b1c-7648df60b9fa.html">norovirus outbreaks on Colorado River rafting trips</a> are common. </p>
<p>As debilitating as the illness it causes can be, the norovirus particle is visually beautiful. It is a type of virus known as “non-enveloped” or “naked,” which means that it never acquires the membrane coating typical of other viruses, such as the flu virus. The norovirus surface is a protein coat, called the “capsid.” The capsid protects the norovirus’ genetic material. </p>
<p>The naked capsid coat is one factor that makes norovirus so difficult to control. Viruses with membrane coatings are susceptible to alcohol and detergents, but not so norovirus. <a href="https://www.cdc.gov/vitalsigns/norovirus/index.html">Norovirus can survive</a> temperatures from freezing to 145 degrees Fahrenheit (about the maximum water temperature in a home dishwasher), soap and mild solutions of bleach. Norovirus can persist on human hands for hours and on <a href="https://doi.org/10.4315/0362-028X.JFP-15-570">solid surfaces and food for days</a> and is also resistant to alcohol-based hand sanitizers. </p>
<p>To make things worse, only a tiny dose of the virus – <a href="https://doi.org/10.1002/jmv.21237">as few as 10 viral particles</a> – is needed to cause disease. Given that an infected person can excrete many billions of viral particles, it’s very difficult to prevent the virus from spreading.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/308693/original/file-20200106-123364-11tc4wa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/308693/original/file-20200106-123364-11tc4wa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/308693/original/file-20200106-123364-11tc4wa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=375&fit=crop&dpr=1 600w, https://images.theconversation.com/files/308693/original/file-20200106-123364-11tc4wa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=375&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/308693/original/file-20200106-123364-11tc4wa.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=375&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/308693/original/file-20200106-123364-11tc4wa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=471&fit=crop&dpr=1 754w, https://images.theconversation.com/files/308693/original/file-20200106-123364-11tc4wa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=471&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/308693/original/file-20200106-123364-11tc4wa.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=471&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Norovirus, also called winter vomiting bug, infects cells in the human intestine causing diarrhea, vomiting and stomach pain.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/norovirus-human-intestine-called-winter-vomiting-1098015311">Kateryna Kon/Shutterstock.com</a></span>
</figcaption>
</figure>
<h2>Susceptibility to norovirus depends on blood type</h2>
<p>When norovirus is ingested, it initially infects the cells that line the small intestine. Researchers don’t know exactly how this infection then causes the symptoms of the disease. But a fascinating aspect of norovirus is that, after exposure, <a href="https://doi.org/10.3390/v11030226">blood type determines, in a large part, whether a person gets sick</a>. </p>
<p>Your blood type – A, B, AB or O – is dictated by genes that determine which kinds of molecules, called oligosaccharides, are found on the surface of your red blood cells. Oligosaccharides are made from different types of sugars linked together in complex ways.</p>
<p>The same oligosaccharides on red blood cells also appear on the surface of cells that line the small intestine. Norovirus and a few other viruses use these oligosaccharides to grab onto and infect the intestinal cells. It’s the specific structure of these oligosaccharides that determines whether a given strain of virus can attach and invade.</p>
<p>The presence of one oligosaccharide, called the H1-antigen, is required for attachment by many norovirus strains. </p>
<p>People who do not make H1-antigen in their intestinal cells make up 20% of the European-derived population and are <a href="https://doi.org/10.1007/s00439-019-02090-w">resistant to many strains of norovirus</a>. </p>
<p>More sugars can be attached to the H1-antigen to give the A, B or AB blood types. People who can’t make the A and B modifications have the O blood type. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/308689/original/file-20200106-123381-ly8t7m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/308689/original/file-20200106-123381-ly8t7m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/308689/original/file-20200106-123381-ly8t7m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=144&fit=crop&dpr=1 600w, https://images.theconversation.com/files/308689/original/file-20200106-123381-ly8t7m.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=144&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/308689/original/file-20200106-123381-ly8t7m.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=144&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/308689/original/file-20200106-123381-ly8t7m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=181&fit=crop&dpr=1 754w, https://images.theconversation.com/files/308689/original/file-20200106-123381-ly8t7m.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=181&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/308689/original/file-20200106-123381-ly8t7m.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=181&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Each blood type is distinguished by a different sugar marker on the red blood cell. Cells lining the intestine also have these sugar markers.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-vector/blood-cells-1777906">Fernando Jose V. Soares/Shutterstock.com</a></span>
</figcaption>
</figure>
<h2>Different strains of norovirus infect different people</h2>
<p>Norovirus evolves rapidly. There are <a href="https://doi.org/10.1097/qco.0000000000000476">29 different strains</a> currently known to infect humans, and each strain has different variants. Each one has different abilities to bind to the variously shaped sugar molecules on the intestinal cell surface. These sugars are determined by blood type. </p>
<p>If a group of people is exposed to a strain of norovirus, who gets sick will depend on each person’s blood type. But, if the same group of people is exposed to a different strain of norovirus, different people may be resistant or susceptible. In general, those who do not make the H1-antigen and people with B blood type will tend to be resistant, whereas people with A, AB, or O blood types will <a href="https://doi.org/10.1002/wsbm.1355">tend to get sick</a>, but the pattern will depend on the specific strain of norovirus.</p>
<p>This difference in susceptibility has an interesting consequence. When an outbreak occurs, for example, on a cruise ship, roughly a third of the people may escape infection. Because they do not know the underlying reason for their resistance, I think spared people engage in <a href="https://www.britannica.com/science/magical-thinking">magical thinking</a> – for example, “I didn’t get sick because I drank a lot of grape juice.” Of course, these mythical evasive techniques will not work if the next outbreak is a strain to which the individual is susceptible. </p>
<h2>Immunity to norovirus is short-lived</h2>
<p>A norovirus infection provokes a robust immune response that eliminates the virus in a few days. However, the response appears to be short-lived. Most studies have found that immunity guarding against reinfection with the same norovirus strain lasts <a href="https://doi.org/10.1002/eji.201545512">less than six months</a>. Also, infection with one strain of norovirus offers little protection against infection from another. Thus, you can have repeated bouts with norovirus.</p>
<p>The diversity of norovirus strains and the impermanence of the immune response complicates development of an effective vaccine. Currently, clinical trials are testing the effects of <a href="https://investors.vaxart.com/news-releases/news-release-details/vaxarts-tableted-oral-bivalent-norovirus-vaccine-meets-primary">vaccines made from the capsid proteins</a> of the two most prevalent norovirus strains. </p>
<p>In general, these experimental vaccines produce <a href="https://doi.org/10.1093/infdis/jiw259">good immune responses</a>; the <a href="https://clinicaltrials.gov/ct2/show/NCT03897309">longevity</a> of the immune response is now <a href="https://clinicaltrials.gov/ct2/show/NCT03039790">under study</a>. The next phase of clinical trials will test if the vaccines actually prevent or <a href="https://clinicaltrials.gov/ct2/show/NCT03039790">reduce the symptoms of norovirus infection</a>.</p>
<p>[ <em>Like what you’ve read? Want more?</em> <a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=likethis">Sign up for The Conversation’s daily newsletter</a>. ]</p><img src="https://counter.theconversation.com/content/129125/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Patricia L. Foster receives funding from the US Army Research Office. She is a member of the Union of Concerned Scientists and Concerned Scientists at Indiana University.</span></em></p>Norovirus, the winter vomiting bug, is highly infectious among people in confined places – like cruise ships. But not everyone is equally vulnerable. Your blood type may determine if you get sick.Patricia L. Foster, Professor Emerita of Biology, Indiana UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1263512020-01-07T19:02:34Z2020-01-07T19:02:34ZCruise ships can be floating petri dishes of gastro bugs. 6 ways to stay healthy at sea this summer<figure><img src="https://images.theconversation.com/files/305123/original/file-20191204-70105-zlvt6v.jpg?ixlib=rb-1.1.0&rect=0%2C8%2C5615%2C3715&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Norovirus is the most common cause of gastro outbreaks on cruise ships.</span> <span class="attribution"><span class="source">From shutterstock.com</span></span></figcaption></figure><p>A cruise can be the perfect summer holiday. But cruise ships, with hundreds, even thousands of people in close quarters, can also be a hotbed of germs.</p>
<p>In particular, cruises are somewhat notorious for outbreaks of gastro. One study, which looked at <a href="http://microbiology.publish.csiro.au/?paper=MA17065">close to 2,000 cruises</a> docking in Sydney, found 5% of ships reported they’d had a gastro outbreak on board.</p>
<p>If you’re about to head off on a cruise, there’s no need to panic. There are some precautions you can take to give yourself the best chance of a happy, gastro-free holiday.</p>
<h2>What causes gastro?</h2>
<p>Viruses are the leading cause of acute gastroenteritis in Australia. Norovirus is the main culprit, causing an estimated <a href="http://dx.doi.org/10.1016/j.ijid.2014.08.006">2.2 million cases</a> of gastro each year.</p>
<p>Norovirus is usually transmitted from <a href="https://doi.org/10.1111/j.1708-8305.2008.00200.x">person-to-person</a> via the faecal-oral route, where virus particles found in the stool of one person end up being swallowed by another person. </p>
<p>Extremely <a href="https://doi.org/10.3201/eid1410.080117">large numbers</a> of virus particles are shed in faeces and vomit, yet a person only needs to ingest a <a href="http://dx.doi.org/10.1002/jmv.21237">very small number</a> of virus particles to catch the infection.</p>
<hr>
<p>
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<strong>
Read more:
<a href="https://theconversation.com/health-check-how-long-are-you-contagious-with-gastro-98769">Health Check: how long are you contagious with gastro?</a>
</strong>
</em>
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<hr>
<p>Norovirus is hardy and <a href="https://doi.org/10.3181/00379727-140-36508">can resist</a> acid conditions (like those in the gut) and moderate temperatures (at which we wash clothes or reheat food, for example). Further, many chemicals used in <a href="http://dx.doi.org/10.1016/j.ijfoodmicro.2013.11.018">cleaning products</a> and <a href="http://dx.doi.org/10.1016/j.jhin.2015.02.019">hand sanitisers</a> don’t effectively remove norovirus.</p>
<p>The main symptoms of gastro caused by norovirus are diarrhoea and vomiting. Symptoms normally only last for a short period (<a href="http://doi.org/10.1016/j.jcv.2008.10.009">two to three days</a>), and will stop on their own. The main risk is dehydration, which is of most concern for young children and the elderly.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/306227/original/file-20191211-95115-c0b1fi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/306227/original/file-20191211-95115-c0b1fi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/306227/original/file-20191211-95115-c0b1fi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/306227/original/file-20191211-95115-c0b1fi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/306227/original/file-20191211-95115-c0b1fi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/306227/original/file-20191211-95115-c0b1fi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/306227/original/file-20191211-95115-c0b1fi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Norovirus is the number one viral cause of gastro in Australia.</span>
<span class="attribution"><span class="source">From shutterstock.com</span></span>
</figcaption>
</figure>
<h2>Norovirus on cruise ships</h2>
<p>Generally, a cruise ship will declare a “gastro outbreak” once <a href="https://www.cdc.gov/nceh/vsp/surv/gilist.htm">2-3%</a> of passengers or crew are ill with gastro symptoms. So on a ship of 2,000 passengers, 40-60 people would need to be unwell before an outbreak is declared.</p>
<p>An <a href="http://microbiology.publish.csiro.au/?paper=MA17065">Australian study</a> found 5% of cruise ships that arrived in Sydney between 2007 and 2016 reported gastro outbreaks (98 out of 1967). Of the outbreaks with a known cause, 93% were from norovirus.</p>
<p>Reports pop up in the news from time to time when there’s a significant outbreak, like when the Sea Princess recorded <a href="https://www.abc.net.au/news/2018-01-03/two-hundred-sick-as-gastro-hits-sea-princess/9302372">200 cases of gastro</a> caused by norovirus in 2018.</p>
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<p>
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<strong>
Read more:
<a href="https://theconversation.com/viruses-arent-all-nasty-some-can-actually-protect-our-health-117678">Viruses aren't all nasty – some can actually protect our health</a>
</strong>
</em>
</p>
<hr>
<h2>How does it spread?</h2>
<p>You can be infectious with norovirus <a href="https://doi.org/10.1016/j.jhin.2004.07.001">before symptoms appear and even after they resolve</a>, so a person might unknowingly bring norovirus onto a cruise with them.</p>
<p>On a cruise ship, norovirus is mainly spread directly from <a href="https://doi.org/10.1111/j.1708-8305.2008.00200.x">person to person</a>. This is not surprising as many activities on a cruise involve mixing with other passengers in a reasonably closed space. </p>
<p>While a handshake is a normal greeting, it’s a fairly unsanitary practice. A <a href="https://journals.viamedica.pl/international_maritime_health/article/view/IMH.2016.0034/36943">recent study</a> suggested a “fist-bump” should be promoted on cruises, while a modified version dubbed the “cruise-tap” (where only two knuckles are touched) could be even better.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/306225/original/file-20191211-95125-2l037o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/306225/original/file-20191211-95125-2l037o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/306225/original/file-20191211-95125-2l037o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/306225/original/file-20191211-95125-2l037o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/306225/original/file-20191211-95125-2l037o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/306225/original/file-20191211-95125-2l037o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/306225/original/file-20191211-95125-2l037o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">If you do catch gastro on a cruise, you’ll probably be asked to stay in your room so as not to give it to other passengers.</span>
<span class="attribution"><span class="source">From shutterstock.com</span></span>
</figcaption>
</figure>
<p>The other way norovirus typically spreads is from touching <a href="https://doi.org/10.1080/15459624.2018.1531131">contaminated surfaces</a>. A person with norovirus may not wash their hands properly (or at all) after going to the toilet, leaving many invisible norovirus particles on their hands.</p>
<p>When this person touches surfaces (for example hand rails, buttons in the lift, or utensils at the buffet) they leave behind norovirus particles. Other people can then touch these surfaces and transfer the particles to their own hands. Then, if they put their hands to their mouth, they can give themselves the virus.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/health-check-should-i-use-antibacterial-hand-sanitisers-21384">Health Check: should I use antibacterial hand sanitisers? </a>
</strong>
</em>
</p>
<hr>
<p>It’s rare to <a href="https://doi.org/10.1017/s0950268803008689">inhale norovirus particles</a> from the air, but it can occur, usually if someone with the virus vomits nearby.</p>
<p>While norovirus can be found in food, cruise ships have strict food handling practices to prevent the spread of illnesses such as norovirus. Though this doesn’t mean it’s unheard of.</p>
<h2>How to avoid catching norovirus</h2>
<p>It’s impossible to completely eliminate the risk of catching norovirus, but there are some things you can do to minimise your risk:</p>
<ul>
<li>wash your hands well and frequently, especially before eating</li>
<li>don’t rely on hand sanitisers (hand washing is always better)</li>
<li>don’t share food, drinks or eating utensils</li>
<li>don’t touch food with your hands</li>
<li>reduce unnecessary contact with communal surfaces</li>
<li>leave the area if someone vomits.</li>
</ul>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/prepare-for-a-healthy-holiday-with-this-a-to-e-guide-69552">Prepare for a healthy holiday with this A-to-E guide</a>
</strong>
</em>
</p>
<hr>
<p>If you do get gastro symptoms on a cruise, it’s important you tell the medical personnel as soon as possible and follow their instructions. </p>
<p>You may be asked to stay in your cabin for a short period so as not to infect other passengers; just as you would wish another infected passenger not to spread the virus to you and your family. </p>
<p>The sooner the crew can identify a gastro case, the sooner they can start extra clean-up procedures and take further precautions to prevent an outbreak. Also, if you tell medical personnel, they may be able to provide medication and organise appropriate food to be delivered to your room.</p>
<p>Above all, to minimise the risk of gastro spoiling your cruise, wash your hands thoroughly and often.</p><img src="https://counter.theconversation.com/content/126351/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Leesa Bruggink does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>A cruise can be a fantastic holiday. But it certainly won’t be if you end up confined to the bathroom with gastro.Leesa Bruggink, Senior Scientist, Enteric Viruses Laboratory, Victorian Infectious Diseases Reference LaboratoryLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/964562018-05-22T21:01:17Z2018-05-22T21:01:17ZWhy you may never eat raw oysters again<figure><img src="https://images.theconversation.com/files/219516/original/file-20180517-26286-f3sb76.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Eating raw oysters can put you at risk of food-borne illnesses, such as norovirus, hepatitis A and salmonella. And, sadly, hot sauce, lemon juice and alcohol do not reduce the risks.</span> <span class="attribution"><span class="source">(Shutterstock))</span></span></figcaption></figure><p>Many people look forward to raw oysters, and raw oyster bars are popular at some trendy restaurants. However, they (along with other under-cooked seafood) can put you at risk for food-borne illnesses.</p>
<p>Recently, <a href="http://www.cbc.ca/news/canada/british-columbia/norovirus-oysters-april-2018-1.4649715">many people became ill in British Columbia, Alberta and Ontario</a> after eating raw oysters harvested from B.C. farms. </p>
<p>Although the actual causes of the contamination are still unknown, <a href="https://www.canada.ca/en/public-health/services/public-health-notices/2017/public-health-notice-ongoing-outbreak-norovirus-gastrointestinal-illnesses-linked-undercooked-oysters-british-columbia.html">human sewage in the marine environment is the likely culprit</a> in this outbreak. </p>
<p><a href="https://www.cdph.ca.gov/Programs/OPA/Pages/NR18-027.aspx">People in the United States have also become sick</a> from eating these Canadian raw oysters. </p>
<p>Norovirus is actually the most common cause of food-borne illness caused by the consumption of bivalve shellfish contaminated with human fecal matter. In fact, some recent research done in the United Kingdom found that <a href="http://www.foodsafetynews.com/2018/05/norovirus-found-in-almost-70-percent-of-oysters-for-sale-in-uk/#.Wv19O4iUubg">almost 70 per cent of the raw oysters sold in the U.K. contain norovirus</a>, although it is uncertain if all of the virus is actually infectious. </p>
<p>Oyster-associated norovirus outbreaks commonly result from contamination at the source in the growing waters. Oyster beds themselves can become contaminated due to land-based sewage outflow or sewage disposal from oyster harvesters.</p>
<h2>Can you tell if a raw oyster is bad?</h2>
<p>No, an oyster that contains harmful bacteria or viruses does not look, smell or even taste different from any other oyster.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/219517/original/file-20180517-26286-13mmrjl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/219517/original/file-20180517-26286-13mmrjl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/219517/original/file-20180517-26286-13mmrjl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/219517/original/file-20180517-26286-13mmrjl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/219517/original/file-20180517-26286-13mmrjl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/219517/original/file-20180517-26286-13mmrjl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/219517/original/file-20180517-26286-13mmrjl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The safest way to eat oysters is to cook them until they reach an internal temperature of 90˚C.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<p>Besides norovirus, there are a number of other bacteria and viruses that we need to be concerned with in raw oysters. </p>
<p>The most important bacteria are two in the genus Vibrio. One is called <a href="https://www.nejm.org/doi/full/10.1056/NEJMoa051594">Vibrio parahaemolyticus</a> and the other Vibrio vulnificus. The latter bacterium can cause more severe illness, but are more often a problem in the U.S. than in Canada. </p>
<p><a href="http://www.dx.doi.org/10.1128/AEM.71.2.893-897.2005">Salmonella has also been found in raw oysters</a>. And, when it comes to viruses, hepatitis A can be found in raw oysters and cause illness, although norovirus is the one that has caused most of the problems of late.</p>
<h2>How do raw oysters become contaminated?</h2>
<p>Human sewage in the marine environment is believed to be the most probable cause of oyster contamination with norovirus. </p>
<p>But Vibrio bacteria are believed to be a natural part of the marine environment where oysters live. It is only when water temperatures rise that these bacteria can become a problem. </p>
<p>In fact, <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4772208/pdf/ijerph-13-00188.pdf">global warming is thought by some to be responsible for some outbreaks linked to Vibrio species</a>. </p>
<p>Because oysters feed by filtering water, both bacteria and viruses can actually concentrate themselves in the tissues of the oysters before they are eaten by consumers.</p>
<h2>Who is most at risk of infection?</h2>
<p>Acute gastrointestinal illnesses such as norovirus and vibriosis are common in North America, and can affect all age groups. </p>
<p>However, pregnant women, people with compromised immune systems, young children and the elderly are at risk for developing more serious complications. </p>
<p>For a certain type of Vibrio bacteria, which is more common in the U.S., <a href="https://www.fda.gov/Food/ResourcesForYou/HealthEducators/ucm085365.htm">people with underlying health conditions, such as liver disease, are at a higher risk of more serious complications or even death</a>. </p>
<h2>How to purchase oysters safely</h2>
<p>First, shop from reliable sources and choose fresh oysters with intact shells and without abnormal odour. When the shell is tapped, it should close tightly. Throw away any oysters with shells already opened.</p>
<p>Check the expiry date of pre-packaged shucked oysters. Ensure they are stored properly at 4˚C or below for chilled products, or at -18˚C or below for frozen products.</p>
<p>It is best to place raw, store-bought oysters into a cold thermos bag when transporting them home. This will minimize the time that the oysters are exposed to room temperature, which favours the growth of bacterial pathogens such as Vibrio. </p>
<p>Chilled oysters should be consumed within one to two days. Oysters in the shell should be placed in containers with a cover to prevent cross-contamination in the refrigerator.</p>
<h2>How to cook oysters at home</h2>
<p>To protect yourself, do not eat oysters raw or under-cooked. The safest way is to <a href="https://www.seafoodhealthfacts.org/seafood-safety/general-information-patients-and-consumers/seafood-safety-issues-specific-products-0">cook your oysters</a> until they reach an internal temperature of 90˚C.</p>
<p>In the shell: After the shells open, you should boil the live oysters for another three to five minutes. Also, do not cook too many oysters in the same pot because the ones in the middle may not get fully cooked. Finally, discard any oysters that do not open during cooking.</p>
<p>In a steamer: Add oysters to water that is already steaming and cook the live oysters for four to nine minutes.</p>
<p>Shucked products should be boiled for three minutes, fried at 375°F for at least three minutes or baked at 232°C (450°F) for 10 minutes.</p>
<p>Be sure to wash your hands, utensils and surfaces well with hot water and soap after you have handled raw oysters. You do not want to cross-contaminate other ready-to-eat foods in your kitchen. </p>
<h2>A few oyster myths</h2>
<p><strong>1. You only get sick from eating oysters during the warmer months of the year.</strong></p>
<p>While it is true that most vibriosis cases occur during the warmer months of the year, when the water temperatures are higher and there is a better chance of the Vibrio bacteria growing more rapidly, cases have been reported all year round. </p>
<p>For norovirus, a number of studies have found that you can actually find higher levels in commercially harvested shellfish during the winter. <a href="https://academic.oup.com/jid/article/181/Supplement_2/S284/1023787">Some studies have shown that there is a cold weather peak in relation to the number of norovirus gastroenteritis cases that occur</a>.</p>
<p><strong>2. If you avoid eating raw oysters from polluted waters, you will be safe.</strong></p>
<p>False. Vibrio bacteria are not a result of pollution as they are natural inhabitants of the marine environment. So, although oysters should always be obtained from reputable sources, eating oysters from “clean” waters or in reputable restaurants with a high turnover does not guarantee that you will not get sick.</p>
<p><strong>3. Eating raw oysters with hot sauce and lemon juice will kill the bacteria and viruses that can cause food-borne illness.</strong></p>
<p>No, this is false. Hot sauce and/or lemon juice will not significantly affect any of the food-borne pathogens.</p>
<p><strong>4. Eating raw oysters while drinking alcohol will kill the bacteria and viruses that can cause food-borne illness.</strong></p>
<p>Again, this is false.</p><img src="https://counter.theconversation.com/content/96456/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jeffrey M. Farber does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>In the wake of a norovirus outbreak traced to raw oysters from British Columbia, our expert explains how to eat this culinary delicacy safely.Jeffrey M. Farber, Professor of Food Safety, University of GuelphLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/918862018-02-20T11:40:06Z2018-02-20T11:40:06ZWhy is there a norovirus outbreak at the Winter Olympics? 4 questions answered<figure><img src="https://images.theconversation.com/files/206792/original/file-20180216-50536-1gg4qb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A digitally colorized cluster of norovirus virions.</span> <span class="attribution"><a class="source" href="https://phil.cdc.gov/Details.aspx?pid=10708">CDC/ Charles D. Humphrey</a></span></figcaption></figure><p><em>Editor’s note: At the Winter Olympics in Pyeongchang, South Korea, there have been more than <a href="https://www.reuters.com/article/us-olympics-2018-virus/swiss-skiers-first-athletes-hit-by-norovirus-at-games-idUSKCN1G009H">200 confirmed cases</a> – mostly security and games personnel, but also two athletes. We asked Kartikeya Cherabuddi, an infectious disease expert at the University of Florida, to explain what this virus is and how it spreads.</em> </p>
<h2>1. What is norovirus?</h2>
<p>What do the Olympics, cruise ships and nursing homes have in common? They all involve humans congregating in a small area – creating a comfortable environment for norovirus outbreaks. </p>
<p>Norovirus is a very contagious virus. It’s <a href="https://www.cdc.gov/features/norovirus/index.html">a common cause of gastroenteritis</a>, or inflammation of the intestine, worldwide.</p>
<p>The symptoms start as abdominal cramps and nausea. Vomiting – more common in children – and diarrhea – more common in adults – can also occur. About half of cases involve a low-grade fever around 100.5°F. </p>
<p>Some people have no symptoms. In fact, as many as <a href="https://dx.doi.org/10.3201/eid1410.080117">one-third of infected people</a> show no symptoms but still pass the viruses in the stool. </p>
<p>Norovirus spreads from an infected person mainly by direct contact (such as shaking hands), by touching an infected surface or though contaminated water and food. Seven in 10 of all contaminated food related norovirus outbreaks are caused by <a href="https://www.cdc.gov/media/releases/2014/p0603-norovirus.html">infected food workers</a>.</p>
<p>Norovirus can cause serious illness and even death in children under the age of five, as well as the elderly and people with weakened immune systems. In otherwise healthy people, including athletes, it could cause dehydration and significant discomfort. </p>
<p>There’s no specific treatment. Doctors typically support patients by providing oral and intravenous fluids. The good news is that there are no long-term complications. Recovery is quick, usually in 72 hours. </p>
<p>Outbreaks tend to terminate spontaneously in one to two weeks.</p>
<h2>2. Why is there an outbreak at the Winter Olympics?</h2>
<p>Norovirus infections can spread quickly.</p>
<p><a href="https://dx.doi.org/10.1002/jmv.21237">A very small amount of norovirus</a> – as low as 18 individual viruses – can lead to infection. Norovirus also has a high “<a href="https://dx.doi.org/%2010.1056/NEJMra0804575">secondary attack rate</a>,” meaning that 30 percent of people who are exposed become infected. There is no vaccine. </p>
<p>Like the flu, norovirus has many <a href="https://www.sciencealert.com/scientists-have-discovered-3-new-noroviruses-that-are-causing-gastro-outbreaks">different strains</a>. Prior infection does not provide immunity and using alcohol sanitizers alone cannot prevent its spread. It can also survive on environmental surfaces and is tolerant to freezing and heat up to 140°F. </p>
<p>The Olympic tend to have closed areas with communal dining where a number of people interact with each other. All of these factors enable the infection to spread quickly in 24 to 48 hours, affecting many people.</p>
<p>What’s more, norovirus outbreaks predominantly occur in the winter for reasons that aren’t entirely clear. In a <a href="https://wwwnc.cdc.gov/eid/article/9/1/02-0175-f2">study done in England and Wales</a>, the peak of winter was significantly associated with norovirus outbreaks in health care facilities. </p>
<h2>3. Why was it so hard to prevent the outbreak?</h2>
<p>The South Korean government <a href="https://www.reuters.com/article/us-olympics-2018-virus/olympics-ioc-discussing-norovirus-outbreak-more-cases-reported-idUSKBN1FT07C">took steps to prevent the outbreak</a>, including quarantining security staff; inspecting the hygiene at restaurants and accommodation venues; and testing tap water and drinking sources.</p>
<p>But that may not have been enough to stop the outbreak. The virus could have been present in other people who showed no symptoms.</p>
<p>Norovirus infections are not easy to diagnose. Though infections are very common, they’re often not attributed to norovirus because <a href="http://jcm.asm.org/content/early/2017/10/26/JCM.01457-17">testing</a> is not widely available. </p>
<p>So: It’s winter. An unprecedented number of young people in tight-knit groups are living in closed spaces. They’re serviced by a large number of people temporarily mobilized to meet their needs. They’re confronted with a microbe that appears to be custom-made for such a situation – a microbe to which they have no real immunity and whose diagnosis tends to be delayed. It’s remarkable that the virus didn’t spread farther than it already has. </p>
<h2>4. How do we keep diseases like this from spreading when large groups of people from around the world mass together?</h2>
<p>Illness outbreaks – of norovirus or of other infections – are common whenever large groups of people come together. For example, at the <a href="http://dx.doi.org/10.1136/bjsports-2013-092380">2012 London Olympics</a>, 310 of the 10,568 athletes had a respiratory illness and 123 had a gastrointestinal illness. </p>
<p>Organizers have to pay an extraordinary amount of attention to food and water safety, as well as sanitation. They have to communicate constantly as the situation evolves.</p>
<p>People attending these gatherings also have to take precautions. <a href="https://wwwnc.cdc.gov/travel/destinations/list/">The Centers for Disease Control and Prevention website</a> is a great resource for travel-related advice. At the University of Florida travel clinic, we ensure that people receive the right vaccines and prophylactic medications, as well as offer advice on safety, sanitation and hygiene. </p>
<p>To <a href="https://www.cdc.gov/norovirus/preventing-infection.html">prevent norovirus infections</a>, people should wash their hands thoroughly with soap and water and use alcohol sanitizers, which can be helpful for other infections. Avoid cold foods that require handling, like salads, sandwiches and oysters. If infected, do not prepare food for others for two days even after you feel well. </p>
<p>Finally, at the cost of appearing rude, do not shake hands – wave!</p><img src="https://counter.theconversation.com/content/91886/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kartikeya Cherabuddi does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>There’s a norovirus outbreak at the Winter Olympics. Here’s what that means – and why it’s so hard to stop.Kartikeya Cherabuddi, Physician, University of FloridaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/825422017-08-18T11:06:01Z2017-08-18T11:06:01ZIs it OK to drink cloudy tap water?<figure><img src="https://images.theconversation.com/files/182289/original/file-20170816-32640-178ockk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/download/confirm/130182065?src=m1D2O4A_bwxLScvC1OWkEg-1-4&size=medium_jpg">nikkytok/Shutterstock</a></span></figcaption></figure><p>There’s something offputting about tap water that’s cloudy or milky – it doesn’t invite you to drink it. But is cloudy water actually bad for you? </p>
<p>Researchers at Drexel University in the US <a href="https://ehp.niehs.nih.gov/EHP1090/">found a link</a> between cloudy tap water and outbreaks of gastrointestinal illness, even when the cloudiness was within the limits allowed by some cities. The link, however, is not straightforward.</p>
<p>The technical term for the level of cloudiness of drinking water is “turbidity”. It is a measure of the amount of light that is bounced off material in a sample of water. The instrument used to measure turbidity is a <a href="https://en.wikipedia.org/wiki/Nephelometer">nephelometer</a>. It measure turbidity in nephelometric turbidity units (NTU). The World Health Organisation says that the turbidity of drinking water should not exceed five NTU and should ideally be below one NTU.</p>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/182578/original/file-20170818-7956-fcnmvy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/182578/original/file-20170818-7956-fcnmvy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=426&fit=crop&dpr=1 600w, https://images.theconversation.com/files/182578/original/file-20170818-7956-fcnmvy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=426&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/182578/original/file-20170818-7956-fcnmvy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=426&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/182578/original/file-20170818-7956-fcnmvy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=536&fit=crop&dpr=1 754w, https://images.theconversation.com/files/182578/original/file-20170818-7956-fcnmvy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=536&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/182578/original/file-20170818-7956-fcnmvy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=536&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Turbidity standards of 5, 50 and 500 NTU.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/w/index.php?curid=581276">US Geological Survey/Wikimedia Commons</a></span>
</figcaption>
</figure>
<p>The numerical value of the turbidity in a crystal-clear water sample is typically less than one NTU. But even at higher turbidity levels, we may not be able to notice cloudiness. </p>
<p>The turbidity of purified water at a water treatment works is typically kept below one. Often, the cloudy, raw (unprocessed) water that is purified in a water treatment works contains micro-organisms that cause stomach upsets. The process of water purification makes water look crystal clear and gives some degree of assurance to the engineers that most micro-organisms have been removed. </p>
<p>But crystal-clear water does not always mean bug-free water – it’s not a perfect proxy indicator. The cloudiness is not caused by the bugs but by many other constituents, such as silt, clay and organic matter, which may or may not be carrying bugs. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/182431/original/file-20170817-28160-ob0ewb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/182431/original/file-20170817-28160-ob0ewb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=397&fit=crop&dpr=1 600w, https://images.theconversation.com/files/182431/original/file-20170817-28160-ob0ewb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=397&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/182431/original/file-20170817-28160-ob0ewb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=397&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/182431/original/file-20170817-28160-ob0ewb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=499&fit=crop&dpr=1 754w, https://images.theconversation.com/files/182431/original/file-20170817-28160-ob0ewb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=499&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/182431/original/file-20170817-28160-ob0ewb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=499&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A water-treatment plant.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/download/confirm/576627958?src=Ojzw_DxgswHuJc7kmA4nWw-1-4&size=medium_jpg">Dmitri Ma/Shutterstock</a></span>
</figcaption>
</figure>
<h2>Finding a link</h2>
<p>The researchers at Drexel University analysed existing studies from North America and Europe that investigated the link between drinking-water turbidity and acute gastrointestinal illness, caused by bugs such as norovirus, <em>Giardia</em> and <em>Cryptosporidium</em>. </p>
<p>Of the 14 studies included in the review, ten found an association between water turbidity (as measured at the water treatment plant) and the incidence of acute gastrointestinal illness. </p>
<p>The remaining studies show discrepancies, suggesting that the usefulness of turbidity as a proxy may depend on other things. For example, in the raw water, before purification, high turbidity means high levels of micro-organisms, but there may be no correlation between the levels of turbidity and micro-organisms in the purified water that is supplied to our homes. Also, other factors, such as seasonal changes in water bodies, may influence the levels of turbidity and micro-organisms in water. </p>
<p>Overall, the authors of the study concluded that cloudiness <em>alone</em> can’t be used as an indicator for predicting endemic gastrointestinal illnesses. </p>
<p>It makes sense for the water utilities and process engineers to treat water cloudiness as an indirect indicator of potential bug presence in the water at the water treatment works because, in the raw water, both micro-organisms and fine particles are present and assumed to be represented together by the numerical value of the turbidity. </p>
<h2>Picking up cloudiness along the way</h2>
<p>Water from the tap comes after travelling through kilometres of water supply pipe networks – and it might pick up the cloudiness on the way through broken pipes with or without picking up bugs. There are also local sources of harmless cloudiness in the tap water, for example, scaling in domestic water pipes. </p>
<p>If the tap water looks cloudy, it may still be free from bugs responsible for gastrointestinal illnesses. Unfortunately, without carrying out laboratory testing for tap water samples in your home, it is impossible to confirm the presence of bugs in the water, irrespective of the level of cloudiness.</p><img src="https://counter.theconversation.com/content/82542/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span><a href="mailto:d.saroj@surrey.ac.uk">d.saroj@surrey.ac.uk</a> receives funding from EPSRC </span></em></p>A new study finds a link between cloudy tap water and outbreaks of gastrointestinal illness, such as norovirus.Devendra Saroj, University of SurreyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/713262017-02-28T11:38:27Z2017-02-28T11:38:27ZWant to eradicate viruses? They made us who we are<figure><img src="https://images.theconversation.com/files/158526/original/image-20170227-26306-9wq5yy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The HIV virus.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/spinning-hiv-virus-on-black-background-446279950?src=SCQKGHgbRbczgTJ_jj8c1Q-1-7">Shutterstock</a></span></figcaption></figure><p>It is cold and flu season so many of us are currently under the weather with a virus. But what exactly is a virus? And are they even alive?</p>
<p>Outside a host cell, these weird microscopic particles, or virions, only consist of a tiny piece of genetic information (about 10,000 times less than that contained in the human genome) and a protein or lipid (fatty molecule) shell. Whether these particles are <a href="https://www.scientificamerican.com/article/are-viruses-alive-2004/">living things</a> is the subject of much debate, as they don’t meet many of the usual criteria for life.</p>
<p>While there isn’t any formal agreement on what defines life, <a href="https://www.nasa.gov/vision/universe/starsgalaxies/life's_working_definition.html">most definitions</a> include the ability to adapt to the environment, to reproduce, to respond to stimuli, and to use energy.</p>
<p>While the virus particle may fall short of the definition of life depending on the criteria used, for some virologists like myself, thinking of the virion as the “virus” is like calling a sperm or unfertilised egg a “person”. Sure, a sperm is an essential step towards creating a person, but few people would argue that a sperm or unfertilised egg should be described as the finished product. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/158574/original/image-20170227-18526-1850jxx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/158574/original/image-20170227-18526-1850jxx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/158574/original/image-20170227-18526-1850jxx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/158574/original/image-20170227-18526-1850jxx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/158574/original/image-20170227-18526-1850jxx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/158574/original/image-20170227-18526-1850jxx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/158574/original/image-20170227-18526-1850jxx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Flu: part virus, part human.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/asian-caucasian-woman-flu-311618567?src=NpYL996iFBZHWFTIUAfZnA-1-21">Shutterstock</a></span>
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<p>Much like a sperm, virions are produced in the millions. Many will never reach their destination and are lost and degrade in the environment. It is only when the virus binds to and enters a target cell that its cycle of replication can begin. </p>
<p>A virion doesn’t even always contain a majority of the molecules a virus can create. For example, the <a href="http://www.nhs.uk/conditions/Norovirus/Pages/Introduction.aspx">norovirus</a> virion contains just three different types of protein and one type of <a href="http://www.bbc.co.uk/bitesize/higher/biology/cell_biology/rna/revision/1/">RNA</a> (a nucleic acid like DNA which uses a different sugar to form its backbone). Infected cells, however, make at least eight different viral proteins and four different viral RNAs. </p>
<p>Nor does the virus particle itself usually result in the symptoms of disease. Typically, when you catch a virus, your symptoms come from either infected cells dying, or your immune response to those infected cells. </p>
<p>For these reasons, some virologists consider the infected cell, rather than the virion, to be the virus. </p>
<h2>I am virus</h2>
<p>While this idea sounds outlandish, from conception to grave, your cells are intricately associated with viruses. Even if you don’t have a cold or the flu, you are still part-virus as human DNA plays host to a range of different viruses.</p>
<p>These are <a href="https://www.britannica.com/science/retrovirus">retroviruses</a>, the best-known example of which is <a href="http://www.nhs.uk/conditions/HIV/Pages/Introduction.aspx">HIV</a>. While HIV only entered the human population relatively recently, viruses very much like it have been infecting us and the creatures we evolved from since long before humans even existed. </p>
<p>While HIV infects immune cells, when a retrovirus instead infects the cells that produce eggs or sperm, the viral DNA can be inherited by any offspring. Over millions of years, these viruses have lost their ability to produce infectious particles, but have in some cases found other vital roles, and are now indispensable for human life. </p>
<p>One well-studied example is a protein called <a href="http://schaechter.asmblog.org/schaechter/2014/06/retroviruses-the-placenta-and-the-genomic-junk-drawer.html">Syncytin-1</a>, which is vital for the development of the placenta. This was originally a retroviral protein which entered the monkey population which gave rise to humans around 24m years ago. If we deleted this protein from our DNA, humanity would rapidly go extinct as we could no longer produce a functional placenta. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/158527/original/image-20170227-26337-1cu0jil.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/158527/original/image-20170227-26337-1cu0jil.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/158527/original/image-20170227-26337-1cu0jil.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/158527/original/image-20170227-26337-1cu0jil.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/158527/original/image-20170227-26337-1cu0jil.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/158527/original/image-20170227-26337-1cu0jil.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/158527/original/image-20170227-26337-1cu0jil.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Transplanting pig organs into humans carries a risk of viral infection.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/pig-breeding-farm-402483784?src=f5fAVrYQQTZY8iSucUg4Ig-1-5">Shutterstock</a></span>
</figcaption>
</figure>
<p>All these viruses which inserted into our DNA long ago are termed <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1187282/">endogenous retroviruses (ERVs)</a>. In humans, ERVs have long since lost the ability to produce infectious virions, but this is not the case in all animals. <a href="https://www.ncbi.nlm.nih.gov/pubmed/24594055">Pig ERVs</a>, for example, can produce infectious particles and are a concern when considering the use of pig organs for transplant, as these are known to be able to infect human cells in the lab.</p>
<h2>Blurred lines</h2>
<p>If a virus is the infected cell, rather than the virion, you could even think of the viruses that can infect us as more than 99.9% human. This is because they need many of the human proteins or other molecules present in your cells and encoded in your DNA to make more virus.</p>
<p>A human cell is vastly more complex than even the largest virus, and viruses can make use of this to compensate for their own simplicity. Viruses and their host cells share many common needs. They need to be able to produce RNA, protein, lipids and have access to the raw materials to generate these. As a host cell already contains all the needed components to achieve this, a virus can simply provide its own instructions, in the form of the viral genome, and let the cell do most of the work. </p>
<p>It takes many more cellular proteins to make a virus, than it does viral proteins. A virus only needs to provide instructions for the few components the host cell cannot produce. An example of this would be viruses which have a virion with a lipid membrane, such as influenza. This membrane is usually recycled from host <a href="http://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1000085">cell membranes</a>. The addition of a couple of viral proteins converts this into the membrane coat of the virion.</p>
<p>This use of host components by viruses also makes it clear why it has been so difficult to develop effective antiviral drugs. Much as with cancer treatment, there is very little to distinguish infected cells from normal human cells, which makes coming up with a drug that will only target infected cells extremely challenging. To be effective, you have to target that tiny part of the infected cell that is purely virus, without harming the remainder. </p>
<p>So are viruses alive? It’s still not settled, and really depends on what you think a virus is. What does seem clear, however, is that the viruses which infect us can be seen as part human, and we are part virus.</p><img src="https://counter.theconversation.com/content/71326/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Edward Emmott does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>We have an awful lot in common with the viruses that infect us.Edward Emmott, Research Associate in Virology, University of CambridgeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/711742017-01-12T15:41:56Z2017-01-12T15:41:56ZWhy is the norovirus such a huge problem for the NHS?<figure><img src="https://images.theconversation.com/files/152532/original/image-20170112-25864-11cd2r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/pic-382090795/stock-photo-man-doing-vomiting-gesture.html?src=k0_IwFzkqvQhr8cOA_QCHg-1-9">CHAjAMP/Shutterstock.com</a></span></figcaption></figure><p>Norovirus, also known as winter vomiting disease, is on the rise again according to a report in the <a href="http://dx.doi.org/10.1136/bmj.j117">BMJ</a>. A familiar set of warnings about ward closures and avoiding visits to patients in hospital was also issued, but why does this one virus cause the NHS such difficulty?</p>
<p>While norovirus does occur year-round, there is a <a href="https://dx.doi.org/10.3201/eid0901.020175">winter peak</a> in cases that clashes with the winter rush on the NHS. The symptoms of norovirus – diarrhoea and vomiting – typically last a day or two. While you may spend those days wishing you were dead, the chances of long-term harm from the infection are extremely low if you are otherwise healthy. The people most at risk from norovirus are the very young, the elderly and people with impaired immune systems (those said to be immunocompromised). Unfortunately, these are exactly the groups most likely to find themselves in hospital. </p>
<p>As a result of advances in transplant medicine and cancer treatment that suppress or affect the immune system, these immunocompromised patients make up an increasingly large portion of the population. While norovirus only lasts a few days at most in healthy people, those who are immunocompromised can <a href="http://www.clinicalmicrobiologyandinfection.com/article/S1198-743X(16)30616-4/abstract">struggle to clear the infection</a>; it can linger for weeks, months or even years. Fortunately, it is rare that full-blown norovirus symptoms are experienced for this long. It does make it hard to absorb food and gain weight, which is a worry after major surgery and can make recovery much more difficult. As such these patients are a particular concern.</p>
<p>It is very easy to pass on the norovirus. One tablespoon of diarrhoea from a single patient can contain enough infectious virus to infect everyone in the world many times over. To make things worse, like many other viruses, people may remain infectious for several days after symptoms have resolved and not every infected person may even be symptomatic. Many cases are traced back to <a href="https://www.cdc.gov/norovirus/food-handlers/work-with-food.html">food handlers</a> who may appear well and have no idea they are infectious. The virus can be spread through touching infected surfaces or material and a lack of suitable handwashing or hygiene before.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/152534/original/image-20170112-25850-1rhzxmn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/152534/original/image-20170112-25850-1rhzxmn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/152534/original/image-20170112-25850-1rhzxmn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/152534/original/image-20170112-25850-1rhzxmn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/152534/original/image-20170112-25850-1rhzxmn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/152534/original/image-20170112-25850-1rhzxmn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/152534/original/image-20170112-25850-1rhzxmn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Norovirus is often passed on by people handling food.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/download/confirm/121829743?src=Aa2ZmeJnnmu3iyyZjToipQ-1-9&id=121829743&size=medium_jpg">Juan Gaertner/Shutterstock.com</a></span>
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<p>Outbreaks tend to occur in closed environments such as hospitals, cruise ships, schools and retirement homes, as these all share common dining and social areas and have many people eating food prepared by others. In the case of hospitals, many of these have a food court or canteen which is shared by staff, patients and visitors. In summer, many escape outdoors on lunch breaks to enjoy the weather. But in winter when norovirus peaks, everyone crowds together inside, away from the cold.</p>
<h2>An expensive virus</h2>
<p>Hospital staff are at an increased risk of catching norovirus themselves as they deal with large numbers of patients. This is not only unpleasant for the individuals concerned, but also means it’s possible for asymptomatic staff to spread the virus to patients and so exacerbate the problem. For this reason hospitals are very careful about decontamination, staff training, and discouraging ill staff from working for up to 48 hours after symptoms have resolved. </p>
<p>For an organisation which runs 24/7, and relies on a great deal of shift work, this can be very disruptive. All these disruptions come at a cost – lost hospital beds and closed wards, at a time when beds are already at a premium. In the two weeks before Christmas 2016, there were <a href="http://dx.doi.org/10.1136/bmj.j117">15 hospital outbreaks of norovirus</a> in the UK, 14 of which resulted in closed wards or restrictions on patient admissions. Past estimates of the costs of norovirus to the NHS put the total at <a href="https://dx.doi.org/10.3201/eid1010.030941">over £100m</a> (in 2002-03 prices). This is the same as employing over 3,000 extra specialist nurses, or around a third of the total cancer drugs budget.</p>
<p>The <a href="http://dx.doi.org/10.1371/journal.pone.0151219">cost to the global economy</a> of norovirus has been estimated at a whopping US$44 billion, with US$4.2 billion of that to healthcare systems. At a time when NHS budgets are stretched, and hospitals are in debt, these additional costs are ones that hospitals can ill afford. With other seasonal and highly contagious diseases such as influenza, the NHS is able to offer and encourage its staff to take up <a href="https://twitter.com/nhsflufighter">free vaccinations</a> in order to try and reduce the impact on staff, patient and visitor health. However, the absence of a vaccine means this is not yet an option for norovirus.</p>
<h2>Vaccine trials are underway</h2>
<p>While no drugs or vaccines are available, several vaccine candidates are <a href="http://dx.doi.org/10.1016/j.vaccine.2016.03.077">in clinical trials</a>. Sadly, immunity to norovirus does not last for long so, much like the flu vaccine, it is expected that regular vaccinations would be needed to make sure you remain immune. This would still be a huge benefit, and allow vaccination of workers at particular risk, or most likely to transmit the virus, such as NHS staff or those in the catering industry. The recent <a href="http://science.sciencemag.org/content/early/2016/08/24/science.aaf5211">discovery</a> of a means of growing different human norovirus strains in the lab, rather than having to rely on related animal viruses for research, will also boost efforts to find antivirals to help treat infection. </p>
<p>If you have norovirus, there is little your GP or hospital can do for you. The most a visit in person is likely to achieve is to spread the virus to other people. The <a href="http://www.nhs.uk/conditions/Norovirus/Pages/Introduction.aspx">NHS recommends</a> that you stay at home, drink lots of water and, if you are concerned, phone your GP or NHS 111 for further advice.</p><img src="https://counter.theconversation.com/content/71174/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Edward Emmott does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The norovirus costs the NHS in excess of £100 million – the equivalent of employing over 3,000 specialist nurses.Edward Emmott, Research Associate in Virology, University of CambridgeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/343512015-01-07T02:36:18Z2015-01-07T02:36:18ZExplainer: what is gastroenteritis and why can’t I get rid of it?<figure><img src="https://images.theconversation.com/files/67627/original/image-20141218-31046-1a0v5p.jpg?ixlib=rb-1.1.0&rect=0%2C738%2C3738%2C2764&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Symptoms can occur as soon as 30 minutes after exposure to the culprit organism or toxin.</span> <span class="attribution"><a class="source" href="http://www.shutterstock.com/cat.mhtml?lang=en&language=en&ref_site=photo&search_source=search_form&version=llv1&anyorall=all&safesearch=1&use_local_boost=1&search_tracking_id=N0GhD_GHoSLslCeW0RaaZg&searchterm=vomiting&show_color_wheel=1&orient=&commercial_ok=&media_type=images&search_cat=&searchtermx=&photographer_name=&people_gender=&people_age=&people_ethnicity=&people_number=&color=&page=1&inline=103672964">Anton Brand/Shutterstock</a></span></figcaption></figure><p>We’ve all experienced the abdominal cramps and the urge to get to a toilet – quickly! When the stomach and intestinal tract become inflamed, our bodies respond with the sudden onset of diarrhoea, associated nausea and vomiting, abdominal cramping and pain. </p>
<p>Transmissible gastroenteritis is colourfully known as “Montezuma’s revenge”, “Delhi belly”, “stomach flu” and “viral gastro” but let’s use the term “infectious gastroenteritis”. This includes food poisoning, where bacterial toxins consumed in contaminated food rapidly cause symptoms. </p>
<p>Although infectious gastroenteritis usually resolves on its own, in some cases it can lead to severe consequences, chiefly through dehydration. Worldwide, 1.45 million people <a href="http://www.ncbi.nlm.nih.gov/pubmed/24981041">die from infectious gastroenteritis</a> each year.</p>
<p>Symptoms can occur as soon as 30 minutes after exposure to the culprit organism or toxin. But most often, <a href="http://www.hnehealth.nsw.gov.au/__data/assets/pdf_file/0011/89786/Symptom_Profile_of_Gastroenteritis.pdf">symptoms develop</a> 12 to 72 hours after exposure. </p>
<p>Acute infectious gastroenteritis usually resolves within two weeks but severe cases can last several weeks. </p>
<h2>Causes</h2>
<p>Viruses such as <a href="http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Rotavirus">rotavirus</a>, <a href="http://access.health.qld.gov.au/hid/infectionsandparasites/viralinfections/norovirus_fs.asp">norovirus</a>, <a href="http://www.cdc.gov/adenovirus/">adenovirus</a> and <a href="http://www.ncbi.nlm.nih.gov/pubmed/21843659">astrovirus</a> are <a href="http://www.nlm.nih.gov/medlineplus/ency/article/000252.htm">common causes</a> of infectious gastroenteritis. Rotavirus is the leading cause of severe acute gastroenteritis in infants and young children. Almost every child in the world <a href="http://www.ncirs.edu.au/immunisation/fact-sheets/rotavirus-fact-sheet.pdf">will suffer</a> at least one infection by the time they are three years old.</p>
<p>Norovirus is the leading cause of gastroenteritis in adults. Norovirus is highly contagious and outbreaks commonly occur in residential care facilities and hospitals. Patients can <a href="http://www.health.gov.au/internet/publications/publishing.nsf/Content/cda-cdna-norovirus.htm-l%7Ecda-cdna-norovirus.htm-l-app2">remain contagious</a> for at least 48 hours after their symptoms have disappeared. </p>
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<img alt="" src="https://images.theconversation.com/files/67159/original/image-20141214-6042-xzvox2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/67159/original/image-20141214-6042-xzvox2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/67159/original/image-20141214-6042-xzvox2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/67159/original/image-20141214-6042-xzvox2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/67159/original/image-20141214-6042-xzvox2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1006&fit=crop&dpr=1 754w, https://images.theconversation.com/files/67159/original/image-20141214-6042-xzvox2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1006&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/67159/original/image-20141214-6042-xzvox2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1006&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Campylonbacter bacteria is a common cause of gastroenteritis.</span>
<span class="attribution"><a class="source" href="http://en.wikipedia.org/wiki/Campylobacter#mediaviewer/File:ARS_Campylobacter_jejuni.jpg">Wikimedia commons</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p><em><a href="http://www.cdc.gov/ecoli/">Escherichia coli</a></em> (e. coli), <em><a href="http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Gastroenteritis_salmonellosis">Salmonella</a></em>, <em><a href="http://www.mayoclinic.org/diseases-conditions/shigella/basics/definition/con-20028418">Shigella</a></em> and <em><a href="http://www.cdc.gov/nczved/divisions/dfbmd/diseases/campylobacter/">Campylobacter</a></em> are <a href="http://www.nlm.nih.gov/medlineplus/ency/article/000254.htm">common causes</a> of bacterial gastroenteritis. They are often found in contaminated foods including raw or undercooked meat, poultry, seafood and unpasteurised milk. </p>
<p>Bacterial gastroenteritis <a href="http://www.cdc.gov/ncidod/dbmd/diseaseinfo/travelersdiarrhea_g.htmParasites">accounts for</a> 80% of cases of traveller’s diarrhoea and is thought to affect 20% to 50% of international travellers.</p>
<p>Some parasites such as <em><a href="http://www.cdc.gov/parasites/giardia/">Giardia lamblia</a></em>, <em><a href="http://www.cdc.gov/parasites/amebiasis/">entamoeba histolytica</a></em> and <em><a href="http://www.cdc.gov/parasites/crypto/">cryptosporidium</a></em> are known to cause gastroenteritis. Although usually <a href="http://www.ncbi.nlm.nih.gov/pubmed/7838606">parasitic gastroenteritis</a> resolves without treatment, people with compromised immune systems can have prolonged symptoms. </p>
<h2>Prevention and treatment</h2>
<p>The use of clean water and good sanitation practices are important for <a href="http://www.jcu.edu.au/jrtph/vol/v02dean.pdf">reducing rates</a> of infectious gastroenteritis. Handwashing with soap has been <a href="http://www.ncbi.nlm.nih.gov/pubmed/12726975">shown to reduce</a> the risk of gastroenteritis by up to 47%. </p>
<p>Of course, avoiding contaminated foods that could harbour toxic bacteria and parasites is also important.</p>
<p>Vaccinations are also effective, particularly for rotavirus. The rotavirus vaccines have seen a <a href="http://www.ncbi.nlm.nih.gov/pubmed/20622508">marked decline</a> in the rate and severity of disease in both developing and developed countries. </p>
<p>Oral rehydration is the cornerstone of treatment for those suffering from mild to moderate dehydration. This can be achieved through a solution containing water, salts and sugar. For severe cases of dehydration, hospitalisation and <a href="http://www.rch.org.au/clinicalguide/guideline_index/Gastroenteritis/">intravenous fluids</a> may be required.</p>
<p>Antibiotics are generally not recommended unless the gastroenteritis is bacterial or parasitic and symptoms are severe. </p>
<h2>Longer-term illnesses</h2>
<p>What if the symptoms of gastroenteritis still persist months or even years into the future?</p>
<p>Mounting evidence links bacterial, viral, and parasitic infections with an increased risk of developing irritable bowel syndrome. <a href="http://www.ncbi.nlm.nih.gov/pubmed/20427395">One study</a> followed patients that developed acute gastroenteritis during a large outbreak in 2000. The prevalence of irritable bowel syndrome at three years was very high at 28.3%. Eight years after the outbreak it was still high at 15.4%. </p>
<p>The <a href="http://www.ncbi.nlm.nih.gov/pubmed/19560575">intestinal barrier</a> allows key nutrients to enter the gut while maintaining a defence against toxins and noxious organisms. This barrier however can be damaged in acute infectious gastroenteritis. Foreign substances can <a href="http://www.ncbi.nlm.nih.gov/pubmed/15606393">then enter</a> the deeper tissues of the gut and promote inflammation.</p>
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<img alt="" src="https://images.theconversation.com/files/67633/original/image-20141218-31025-4vtdsv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/67633/original/image-20141218-31025-4vtdsv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/67633/original/image-20141218-31025-4vtdsv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/67633/original/image-20141218-31025-4vtdsv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/67633/original/image-20141218-31025-4vtdsv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/67633/original/image-20141218-31025-4vtdsv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/67633/original/image-20141218-31025-4vtdsv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Handwashing with soap reduces the risk of gastroenteritis by almost 50%.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/jessicarone/7720202208/in/photolist-cLd49C-7HU8u-hfx3o-9sd1bY-7BXH3b-CgHL7-nxYk8-8eShn7-bAgqYi-9sd1W1-pdBSx-ptfyE4-dBrMDA-aBX5Qp-9dxYGX-8KEdSk-WfHxo-Nx4qX-79xHvC-mhmmbt-GL9U-KzfYk-S4rYn-79xHCG-b3AHpg-9sgfam-9sa34T-47FQB6-79xHoN-oLtCPD-51ibq-mjTeTq-a8qUGw-9Qr9Aj-M7Y6M-5Avmsm-bswUBz-aFigc-9sgeWf-oLJ1MC-4FnRGA-7QjnEr-dje98W-9jvuGB-5dLZ7z-5kHhW4-8Jdao4-2cEoj-8FKJg2-5dRixU">Brandon Otto/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
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<p>A <a href="http://www.ncbi.nlm.nih.gov/pubmed/15247174">study examining patients</a> who had gastroenteritis caused by <em>Shigella</em> found that there were increased mast cell numbers in the gut. Mast cells are known to secrete the hormone serotonin which is important for signalling in the <a href="https://theconversation.com/how-the-bacteria-in-our-gut-affect-our-cravings-for-food-33141">enteric nervous system</a>. This then may be another mechanism by which post-infectious irritable bowel syndrome can develop. </p>
<p>Researchers have also studied what happens, at a cellular level, in the gut after acute gastroenteritis. <a href="http://www.ncbi.nlm.nih.gov/pubmed/14695026">Interstitial cells of Cajal</a> are known as the pacemaker cells of the gut and help digest food and move it through the gut. These <a href="http://www.ncbi.nlm.nih.gov/pubmed/25484117">cells were altered</a> in mice that were exposed to a type of bacterial gastroenteritis. </p>
<h2>Unanswered questions</h2>
<p>We have a reasonably good understanding of the causes of infectious gastroenteritis and treatment. But there’s more we need to learn, especially when it comes to understanding how symptoms might persist over the long term. </p>
<p>We are learning to appreciate the significance of a disordered immune system for long-term gastrointestinal symptoms. This opens the possibility for selective use of anti-inflammatory drugs or <a href="http://www.ncbi.nlm.nih.gov/pubmed/25431489">immune-modifying medications</a> in patients recovering from infectious gastroenteritis.</p><img src="https://counter.theconversation.com/content/34351/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Vincent Ho does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>We’ve all experienced the abdominal cramps and the urge to get to a toilet – quickly! When the stomach and intestinal tract become inflamed, our bodies respond with the sudden onset of diarrhoea, associated…Vincent Ho, Lecturer and clinical academic gastroenterologist, Western Sydney UniversityLicensed as Creative Commons – attribution, no derivatives.