tag:theconversation.com,2011:/us/topics/vomiting-33932/articlesVomiting – The Conversation2023-12-14T13:19:15Ztag:theconversation.com,2011:article/2196632023-12-14T13:19:15Z2023-12-14T13:19:15ZWe think we have found a cause of pregnancy sickness, and it may lead to a treatment<figure><img src="https://images.theconversation.com/files/565507/original/file-20231213-19-swroox.jpg?ixlib=rb-1.1.0&rect=48%2C0%2C5351%2C3540&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Pregnancy sickness is believed to affect 7 in 10 women. </span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/woman-suffering-morning-sickness-bathroom-home-1041217495">Monkey Business Images/Shutterstock</a></span></figcaption></figure><p>Sickness in pregnancy, or hyperemesis gravidarum, is common and is thought to <a href="https://journals.lww.com/obgynsurvey/abstract/2013/09001/the_impact_of_nausea_and_vomiting_of_pregnancy_on.1.aspx">affect</a> seven out of ten women at some time in their pregnancy. But, until recently, very little has been known about why it happens. </p>
<p><a href="https://www.nature.com/articles/s41586-023-06921-9">New research</a> by our team has identified sensitivity to a hormone made in abundance by the developing pregnancy, GDF15, as a contributor to the risk of pregnancy sickness.</p>
<p>This condition can affect pregnant women’s quality of life, even in so-called mild cases. Between 1% and 3% of women <a href="https://pubmed.ncbi.nlm.nih.gov/31515515/">suffer</a> from a severe form of pregnancy sickness when nausea and vomiting are so severe that they lose weight or become dehydrated, or both. In one study, this condition was the most common reason that women were admitted to <a href="https://pubmed.ncbi.nlm.nih.gov/12100809/">hospital</a> in the first three months of pregnancy. </p>
<p>It has been <a href="https://onlinelibrary.wiley.com/doi/10.1111/ppe.12416">associated</a> with worse pregnancy outcomes and its effect lasts beyond the end of pregnancy with some women <a href="https://pubmed.ncbi.nlm.nih.gov/21635201/">reporting</a> psychological distress and being reluctant to <a href="https://pubmed.ncbi.nlm.nih.gov/28241811/">conceive again</a>. </p>
<p>The fact that it develops in early pregnancy and invariably resolves when pregnancy ends strongly suggests that the cause of the sickness comes from the developing pregnancy. But the detail on how and why it happens has remained elusive. This dearth of understanding makes the development of treatments difficult and arguably contributes to the considerable <a href="https://www.pregnancysicknesssupport.org.uk/documents/research%20papers/stigma-of-hg.pdf">stigma</a> associated with this condition. </p>
<h2>GDF15</h2>
<p>GDF15 is a hormone that suppresses food intake in mice by acting, probably exclusively, on a small group of cells at the base of the brain which are also known to induce nausea and vomiting. As such, GDF15 has been under investigation as an <a href="https://pubmed.ncbi.nlm.nih.gov/36754014/">obesity therapy</a>. </p>
<p>Early trials confirm it suppresses appetite in people, but it also causes <a href="https://pubmed.ncbi.nlm.nih.gov/36630958/">nausea and vomiting</a>. It has long been known that it is abundant in human placenta and is present at very high concentrations in the blood of healthy pregnant women. These factors make it a plausible cause, but a detailed understanding of if GDF15 affects the severity of sickness in pregnancy has been lacking. </p>
<p>We used a variety of methods to study how GDF15 increases the risk of pregnancy sickness. We measured GDF15 in the blood of pregnant women attending hospital due to sickness and those attending hospital for other reasons. </p>
<p>We found that women with pregnancy sickness did indeed have higher levels of GDF15. While this was in keeping with GDF15 contributing to the condition, levels of GDF15 in each group overlapped substantially. This suggests that factors other than the absolute amount of GDF15 coming from the developing pregnancy might determine the risk of sickness.</p>
<p>Natural variation in DNA of future mothers contributes to risk of pregnancy sickness. Previous <a href="https://pubmed.ncbi.nlm.nih.gov/29563502/">studies</a> have identified changes in DNA near GDF15 as the biggest determinants of risk of pregnancy sickness. In particular, one rare genetic mutation (present in around one in 1,500 people) that affects the make-up of the GDF15 protein in the blood, has a large <a href="https://pubmed.ncbi.nlm.nih.gov/35218128/">effect</a> on that risk. </p>
<p>To understand the potential impact of this genetic variant on GDF15 levels in the bloodstream, we studied its effects on the protein in lab-grown cells. We discovered that this mutated GDF15 molecule gets stuck inside cells. What’s more, it actually stuck to and trapped “normal” GDF15 – this creates a double hit that hinders the transport of GDF15 out of cells. Healthy people with this mutation have markedly lower levels of GDF15 in their blood, which is consistent with these findings.</p>
<figure class="align-center ">
<img alt="A pregnant woman sits on the edge of a bed clutching her bump." src="https://images.theconversation.com/files/565574/original/file-20231213-21-z851cx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/565574/original/file-20231213-21-z851cx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/565574/original/file-20231213-21-z851cx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/565574/original/file-20231213-21-z851cx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/565574/original/file-20231213-21-z851cx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/565574/original/file-20231213-21-z851cx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/565574/original/file-20231213-21-z851cx.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">Between 1% and 3% of women suffer from a severe form of pregnancy sickness.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/pregnant-woman-sitting-on-bed-holding-310309151">Monkey Business Images/Shutterstock</a></span>
</figcaption>
</figure>
<p>We discovered that DNA changes near GDF15, which are prevalent in about 15 to 30% of people, lower the levels of the hormone. These changes increase the risk of pregnancy sickness by small amounts. Conversely, women with the blood disorder <a href="https://www.nhs.uk/conditions/thalassaemia/">thalassaemia</a>, who have very high levels of GDF15 throughout life, actually reported much less nausea and vomiting in pregnancy.</p>
<h2>A roadmap to treatment</h2>
<p>The conclusion of these studies is clear –- predisposition to higher levels of GDF15 when not pregnant reduces the risk of pregnancy sickness. At first glance, this is rather perplexing because how can having higher levels of a hormone that makes you sick protect against pregnancy sickness? </p>
<p>In fact, several hormone systems exhibit a phenomenon resembling memory, where the sensitivity to a hormone is influenced by previous exposure to that hormone. This seemed like the most plausible explanation for our results. Supporting this theory, mice with persistently high levels of GDF15 in their bloodstream were relatively unresponsive to an acute surge in GDF15 levels. </p>
<p>Our findings suggest that lower levels of GDF15 before pregnancy result in women being hypersensitive to the large amounts of GDF15 being released from the developing pregnancy. This poses two obvious approaches to treatment of this condition –- desensitising women to GDF15 by increasing its levels before pregnancy or blocking its action during pregnancy. </p>
<p>The challenge now is to develop and test strategies to achieve these aims that are safe and acceptable to women at risk from this debilitating condition.</p><img src="https://counter.theconversation.com/content/219663/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sam Lockhart is supported by a Wellcome Trust Clinical PhD Fellowship (225479/Z/22). SL is a named creator of a pending patent application relating to therapy for hyperemesis gravidarum filed by Cambridge Enterprise Limited (GB application No. 2304716.0; Inventor: Professor Stephen O’Rahilly.</span></em></p><p class="fine-print"><em><span>Stephen O'Rahilly has undertaken remunerated consultancy work for Pfizer, Third Rock Ventures, AstraZeneca, NorthSea Therapeutics and Courage Therapeutics. Part of the work in this paper is the subject of a pending patent application relating to therapy for hyperemesis gravidarum filed by Cambridge Enterprise Limited (GB application No. 2304716.0; Inventor: Professor Stephen O’Rahilly). SL and NR are named creators on this patent.</span></em></p>New research has uncovered the hormone that triggers morning sickness, offering hope for millions of women.Sam Lockhart, Wellcome Trust Clinical PhD Fellow, Institute of Metabolic Science and Medical Research Council Metabolic Diseases Unit, University of CambridgeStephen O'Rahilly, Professor and Co-Director of the Institute of Metabolic Science and Director of the Medical Research Council Metabolic Diseases Unit, University of CambridgeLicensed 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>
</figcaption>
</figure>
<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/1685492021-11-08T13:43:51Z2021-11-08T13:43:51ZDo flies really throw up on your food when they land on it?<figure><img src="https://images.theconversation.com/files/423207/original/file-20210925-14-1yipuw9.jpg?ixlib=rb-1.1.0&rect=115%2C121%2C3765%2C2445&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A fly regurgitating digestive juices.</span> <span class="attribution"><span class="source">Carlos Ruiz</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=293&fit=crop&dpr=1 600w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=293&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=293&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=368&fit=crop&dpr=1 754w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=368&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=368&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><em><a href="https://theconversation.com/us/topics/curious-kids-us-74795">Curious Kids</a> is a series for children of all ages. If you have a question you’d like an expert to answer, send it to <a href="mailto:curiouskidsus@theconversation.com">curiouskidsus@theconversation.com</a>.</em></p>
<hr>
<blockquote>
<p><strong>Do flies really throw up on my food when they land on it? – Henry E., age 10, Somerville, Massachusetts</strong></p>
</blockquote>
<hr>
<p>Imagine you’re at a picnic and just about to bite into your sandwich. Suddenly you spot a fly headed your way, homing in on your food with help from its <a href="https://askentomologists.com/2015/02/25/through-the-compound-eye/">compound eyes</a> and antennae. It manages to escape your swatting, lands on the sandwich and then seems to throw up on it!</p>
<p>It can look kind of gross, but the fly might be just airing out its own digested food, or <a href="https://doi.org/10.1093/aesa/90.2.184">spitting on yours</a>.</p>
<p>Most of the <a href="https://www.si.edu/spotlight/buginfo/true-flies-diptera">over 110,000</a> known fly species <a href="https://doi.org/10.1673/031.008.7301">have no teeth</a>, so they cannot chew solid food. Their mouthparts are like a spongy straw. Once they land on your food, they need to release digestive juices to liquefy it into a predigested, slurpable soup they can swallow. In short, some flies are on a <a href="https://doi.org/10.1673/031.008.7301">liquid diet</a>.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/N23E4jYTExk?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">A fly slurping its liquid meal.</span></figcaption>
</figure>
<p>To fit more food in their stomachs, some flies try to reduce the liquid in what they have already eaten. They regurgitate food into vomit bubbles to dry it out a bit. Once <a href="https://doi.org/10.1111/j.1365-3032.1992.tb01193.x">some water has evaporated</a> they can ingest this more concentrated food. </p>
<p>Human beings don’t need to do all this spitting and regurgitating to get nutrients out of our food. But you do produce a digestive juice in your saliva, an enzyme called <a href="https://1md.org/health-guide/digestive/ingredients/alpha-amylase">amylase</a>, which predigests some of the sandwich bread while you chew. Amylase breaks down starch, which you can’t taste, into simple sugars like glucose, which you can taste. That’s why <a href="https://doi.org/10.1093/chemse/bjz010">bread gets sweeter</a> the longer you chew it. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/423212/original/file-20210925-23-18a0vfd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="closeup of a reddish insect with bristly black hairs on its body" src="https://images.theconversation.com/files/423212/original/file-20210925-23-18a0vfd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/423212/original/file-20210925-23-18a0vfd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=459&fit=crop&dpr=1 600w, https://images.theconversation.com/files/423212/original/file-20210925-23-18a0vfd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=459&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/423212/original/file-20210925-23-18a0vfd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=459&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/423212/original/file-20210925-23-18a0vfd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=577&fit=crop&dpr=1 754w, https://images.theconversation.com/files/423212/original/file-20210925-23-18a0vfd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=577&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/423212/original/file-20210925-23-18a0vfd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=577&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Bristles and hair on a Tachinid fly.</span>
<span class="attribution"><span class="source">Maria Cleopatra Pimienta</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Did you know flies can taste food without their mouths? As soon as they land, they use receptors on their feet to decide whether they’re on something nutritious. You may have noticed a fly rubbing its legs together, like a hungry customer getting ready to devour a meal. <a href="https://doi.org/10.1016/j.cub.2020.01.045">This is called grooming</a> – the fly is essentially cleaning itself, and may also clean the <a href="https://doi.org/10.1016/j.conb.2009.07.001">taste sensors</a> on the <a href="https://doi.org/10.1523/JNEUROSCI.0649-14.2014">bristles and fine hair of its feet</a>, to get a better idea of what is in the food it has landed on.</p>
<h2>Should you trash food a fly’s landed on?</h2>
<p>When a fly touches down on your sandwich, that’s probably not the only thing it’s landed on that day. Flies often sit on gross stuff, like a dumpster or decomposing food, that’s full of microbes. The germs can hitch a ride and, if the fly stays put long enough, hop onto your meal. This is much more dangerous than their saliva because <a href="https://doi.org/10.1038/s41598-017-16353-x">some of the microbes</a> can cause diseases, like <a href="https://doi.org/10.1016/j.vaccine.2019.07.078">cholera</a> and <a href="https://doi.org/10.1353/pbm.2006.0005">typhoid</a>. But if the fly doesn’t stay longer than a few seconds the <a href="https://theconversation.com/should-i-throw-away-food-once-a-fly-has-landed-on-it-50895">chances of microbes transferring are low</a>, and your food is probably fine. </p>
<p>To keep insects from landing on your food, you should always cover it. If your house is infested with flies, you can use <a href="https://theconversation.com/how-to-kill-fruit-flies-according-to-a-scientist-81740">simple traps</a> to get rid of them. Carnivorous plants can also eat the flies and help control their population.</p>
<h2>Are flies good for anything?</h2>
<p>Spitting on food and spreading diseases sounds disgusting, but flies aren’t all bad. </p>
<p>Watch closely the next time you’re outside and you might be surprised by how many flies visit flowers to get nectar. They’re an important group of <a href="https://doi.org/10.3390/insects11060341">pollinators</a>, and many plants need flies to <a href="https://theconversation.com/tiny-cacao-flowers-and-fickle-midges-are-part-of-a-pollination-puzzle-that-limits-chocolate-production-154334">help them reproduce</a>.</p>
<p>Flies are also a good source of food for frogs, lizards, spiders and birds, so they’re a valuable <a href="https://doi.org/10.1002/ps.5807">part of the ecosystem</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/429602/original/file-20211101-25-1rfhnd6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="doctor working on patient's foot in background, tubes of maggots in foreground" src="https://images.theconversation.com/files/429602/original/file-20211101-25-1rfhnd6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/429602/original/file-20211101-25-1rfhnd6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=422&fit=crop&dpr=1 600w, https://images.theconversation.com/files/429602/original/file-20211101-25-1rfhnd6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=422&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/429602/original/file-20211101-25-1rfhnd6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=422&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/429602/original/file-20211101-25-1rfhnd6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=531&fit=crop&dpr=1 754w, https://images.theconversation.com/files/429602/original/file-20211101-25-1rfhnd6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=531&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/429602/original/file-20211101-25-1rfhnd6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=531&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 doctor uses sterile maggots like those in these tubes to clean a patient’s foot wound.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/steril-gezüchtete-maden-im-vordergrund-in-reagenzgläsern-zu-news-photo/1213178783">Norbert Försterling/picture alliance via Getty Images</a></span>
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</figure>
<p>Some <a href="https://doi.org/10.1134/S0013873819030023">flies have medical uses</a>, too. For example, doctors use blow fly maggots – the young, immature form of flies – to remove decomposing tissue in wounds. The maggots release antiviral and antimicrobial juices, and these have helped scientists create new treatments for infections.</p>
<p>More importantly, the fruit flies you may have seen flying around ripe bananas in your kitchen have been <a href="https://theconversation.com/ode-to-the-fruit-fly-tiny-lab-subject-crucial-to-basic-research-38465">invaluable in biological research</a>. Biomedical scientists from all over the world study fruit flies to find <a href="https://doi.org/10.1016/S1369-7021(11)70113-4">causes and cures for diseases and genetic disorders</a>. And in <a href="https://faculty.fiu.edu/%7Etheobald/people/">our lab</a>, we study what the world looks like to insects, and how they use their vision to fly. This knowledge can inspire engineers to build better robots.</p>
<p>So, although it’s a nuisance to shoo flies away from your sandwich, maybe you can spare a few bits of your lunch?</p>
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<p><em>Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to <a href="mailto:curiouskidsus@theconversation.com">CuriousKidsUS@theconversation.com</a>. Please tell us your name, age and the city where you live.</em></p>
<p><em>And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.</em></p><img src="https://counter.theconversation.com/content/168549/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jamie Theobald receives funding from the National Science Foundation: IOS-1750833. </span></em></p><p class="fine-print"><em><span>Ravindra Palavalli-Nettimi 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>A fly does some of its digesting outside its body before it even eats any food.Ravindra Palavalli-Nettimi, Postdoctoral Research Associate, Florida International UniversityJamie Theobald, Associate Professor of Biological Sciences, Florida International UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1454402020-09-02T07:34:02Z2020-09-02T07:34:02ZDiarrhoea, stomach ache and nausea: the many ways COVID-19 can affect your gut<figure><img src="https://images.theconversation.com/files/355925/original/file-20200902-18-iwlj10.jpg?ixlib=rb-1.1.0&rect=1%2C0%2C997%2C667&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/midsection-man-stomach-ache-sitting-on-1575442762">Shutterstock</a></span></figcaption></figure><p><a href="https://www.news.com.au/world/coronavirus/health/coronavirus-symptoms-abdominal-pain-named-as-weird-new-symptom/news-story/754912b424b6f18873ab641b6e5e9054">Media reports</a> earlier this week described a Queensland nurse with stomach pains who went on to test positive for COVID-19. </p>
<p>Could stomach pains be another symptom of COVID-19? And if you have stomach pains, should you get tested?</p>
<p>Although we might think of COVID-19 as a respiratory disease, we know it involves the gut. In fact SARS-CoV-2, the virus that causes COVID-19, enters our cells by latching onto protein receptors called ACE2. And the <a href="https://link.springer.com/content/pdf/10.1007/s11684-020-0754-0.pdf">greatest numbers of ACE2 receptors</a> are in the cells that line the gut.</p>
<p>COVID-19 patients with gut symptoms are also more likely to develop <a href="https://bjssjournals.onlinelibrary.wiley.com/doi/10.1002/bjs.11821">severe disease</a>. That’s partly because even after the virus has been cleared from the respiratory system, it can <a href="https://www.thelancet.com/journals/langas/article/PIIS2468-1253(20)30083-2/fulltext?fbclid=IwAR1NxUG0aar9VSzQ82xZVpoGi5OhZsbEAUsx9thqpsAcXiB6eP1U6HWErg4">persist</a> in the gut of some patients for several days. That leads to a high level of virus and longer-lasting disease.</p>
<p>We also suspect the virus can be <a href="https://theconversation.com/we-dont-know-for-sure-if-coronavirus-can-spread-through-poo-but-its-possible-135305">transmitted</a> via the faecal-oral route. In other words, the virus can be shed in someone’s poo, and then transmitted to someone else if they handle it and touch their mouth. </p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/we-dont-know-for-sure-if-coronavirus-can-spread-through-poo-but-its-possible-135305">We don't know for sure if coronavirus can spread through poo, but it's possible</a>
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<h2>What type of gut symptoms are we talking about?</h2>
<p>A <a href="https://bjssjournals.onlinelibrary.wiley.com/doi/10.1002/bjs.11821">review</a> of more than 25,000 COVID-19 patients found about 18% had gastrointestinal symptoms. The most common was diarrhoea followed by nausea and vomiting. Abdominal pain was considered rare. In <a href="https://journals.lww.com/ajg/Documents/COVID_Digestive_Symptoms_AJG_Preproof.pdf">another study</a> only about 2% of COVID-19 patients had abdominal pain.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1270805742782607365"}"></div></p>
<p>Some people believe COVID-19 causes abdominal pain through <a href="https://www.rcpjournals.org/content/clinmedicine/20/3/e4">inflammation</a> of the <a href="https://pubmed.ncbi.nlm.nih.gov/18402644/">nerves of the gut</a>. This is a similar way to how gastroenteritis (gastro) causes abdominal pain.</p>
<p><a href="https://kidney360.asnjournals.org/content/1/6/584">Another explanation</a> for the pain is that COVID-19 can lead to a sudden loss of blood supply to abdominal organs, such as the kidneys, resulting in tissue death (infarction).</p>
<h2>Are gut symptoms recognised?</h2>
<p>The <a href="https://www.cdc.gov/coronavirus/2019-ncov/symptoms-testing/symptoms.html">US Centers for Disease Control</a> has added diarrhoea, nausea and vomiting to its list of recognised COVID-19 symptoms. </p>
<p>However, the <a href="https://www.who.int/health-topics/coronavirus#tab=tab_3">World Health Organisation</a> still only lists diarrhoea as a gastrointestinal COVID-19 symptom. </p>
<p>In Australia, nausea, diarrhoea and vomiting <a href="https://www.health.gov.au/news/health-alerts/novel-coronavirus-2019-ncov-health-alert/what-you-need-to-know-about-coronavirus-covid-19#symptoms">are listed</a> as other COVID-19 symptoms, alongside the classic ones (which include fever, cough, sore throat and shortness of breath). But abdominal pain is not listed.</p>
<p>Advice about symptoms that warrant testing may vary across states and territories.</p>
<h2>How likely is it?</h2>
<p>Doctors often use the concept of <a href="https://asm.org/Articles/2020/June/Why-Pretest-and-Posttest-Probability-Matter-in-the">pre-test probability</a> when working out if someone has a particular disease. This is the chance a person has the disease before we know the test result.</p>
<p>What makes it difficult to determine the pre-test probability for COVID-19 is we don’t know how many people in the community truly have the disease. </p>
<p>We do know, however, COVID-19 in Australia is <a href="https://ourworldindata.org/coronavirus/country/australia?country=%7EAUS">much less common</a> than in many other countries. This affects the way we view symptoms that aren’t typically associated with COVID-19.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1298915716587040769"}"></div></p>
<p>It’s far more common for people’s abdominal pain to be caused by something other than COVID-19. For example, about a <a href="https://pubmed.ncbi.nlm.nih.gov/25147201/">quarter of people</a> at some point in their lives are known to suffer from dyspepsia (<a href="https://gut.bmj.com/content/50/suppl_4/iv2">discomfort or pain</a> in the upper abdomen). But the vast majority of people with dyspepsia do not have COVID-19. </p>
<p>Similarly, irritable bowl syndrome affects <a href="https://pubmed.ncbi.nlm.nih.gov/16409310/">about 9% of Australians</a>, and causes diarrhoea. Again, the vast majority of people with irritable bowel syndrome do not have COVID-19. </p>
<h2>So how about this latest case?</h2>
<p>In the Queensland case, we know the nurse was <a href="https://www.abc.net.au/news/2020-09-02/coronavirus-queensland-calls-testing-rare-unusual-symptoms/12615104">worried</a> he could have had COVID-19 because he was in close contact with COVID-19 patients.</p>
<p>As he seemed otherwise healthy before developing new abdominal symptoms, and considering he <a href="https://www.abc.net.au/news/2020-09-01/qld-covid-border-restrictions-two-new-cases-brisbane-school-shut/12611352">worked on a COVID ward</a>, his pre-test probability was high. Doctors call this a “high index of suspicion” when there is a strong possibility someone may have symptoms due to a disease such as COVID-19.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1300884897209475075"}"></div></p>
<h2>What does this mean for me?</h2>
<p>If you have new gastrointestinal symptoms <em>and</em> you’ve potentially been in contact with someone with COVID-19 <em>or</em> if you also have other classic COVID-19 symptoms (fever, cough, shortness of breath and sore throat) you should definitely get tested. </p>
<p>If you have just gastrointestinal symptoms, you may need to get tested if you’re in a “hotspot” area, or work in a high-risk occupation or industry.</p>
<p>If you have gastrointestinal symptoms alone, without any of these additional risk factors, there is no strong evidence to support testing.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/8-ways-the-coronavirus-can-affect-your-skin-from-covid-toes-to-rashes-and-hair-loss-144483">8 ways the coronavirus can affect your skin, from COVID toes, to rashes and hair loss</a>
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<p>However, if COVID-19 becomes even more common in the community, these symptoms now regarded as uncommon for COVID-19 will become more common.</p>
<p>If you have concerns about any gastrointestinal symptoms, seeing your GP would be sensible. Your GP will provide a balanced assessment based on your medical history and risk profile. </p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/4-unusual-things-weve-learned-about-the-coronavirus-since-the-start-of-the-pandemic-140168">4 unusual things we've learned about the coronavirus since the start of the pandemic</a>
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<img src="https://counter.theconversation.com/content/145440/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>Stomach pains are a rare symptom of COVID-19 and are much more likely to be caused by something else.Vincent Ho, Senior Lecturer and clinical academic gastroenterologist, Western Sydney UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1128612019-05-07T07:14:26Z2019-05-07T07:14:26ZHealth check: why do we get motion sickness and what’s the best way to treat it?<figure><img src="https://images.theconversation.com/files/271258/original/file-20190428-194633-6ojv4w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">More than a quarter of us will suffer from motion sickness.</span> <span class="attribution"><span class="source">From shutterstock.com</span></span></figcaption></figure><p>Motion sickness can be mild, but in some people it’s debilitating, and takes the fun out of a holiday. </p>
<p>We think it’s caused by <a href="https://www.theatlantic.com/health/archive/2015/02/the-mysterious-science-of-motion-sickness/385469/">temporary dysfunction</a> of our brain’s balance centres.</p>
<p>The perception of motion of any sort can bring on <a href="https://www.healthdirect.gov.au/motion-sickness">symptoms of travel sickness</a>. These include dizziness, nausea, vomiting, excessive saliva, rapid breathing and cold sweats.</p>
<p>The good news is, there are strategies and medicines you can use to <a href="https://www.aafp.org/afp/2014/0701/p41.html">prevent motion sickness</a>, or to help you ride it out.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-do-astronauts-get-space-sick-when-they-travel-from-earth-to-the-international-space-station-82888">Curious Kids: Do astronauts get space sick when they travel from Earth to the International Space Station?</a>
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<h2>Ears and eyes disconnect</h2>
<p>As we move through space, multiple sensors in our middle ear, limbs and eyes feed information to our balance centre in our brains to orientate us. It’s when these sources of information are in apparent conflict that we may experience motion sickness.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/271354/original/file-20190429-194609-13mq9yc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/271354/original/file-20190429-194609-13mq9yc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=516&fit=crop&dpr=1 600w, https://images.theconversation.com/files/271354/original/file-20190429-194609-13mq9yc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=516&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/271354/original/file-20190429-194609-13mq9yc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=516&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/271354/original/file-20190429-194609-13mq9yc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=649&fit=crop&dpr=1 754w, https://images.theconversation.com/files/271354/original/file-20190429-194609-13mq9yc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=649&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/271354/original/file-20190429-194609-13mq9yc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=649&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">This diagram of the ear shows the vestibular nerve, which is central to our balance.</span>
<span class="attribution"><span class="source">From shutterstock.com</span></span>
</figcaption>
</figure>
<p>For example, in those who are particularly susceptible, watching certain movies can induce motion sickness as our eyes indicate we are moving, although other sensors confirm we are stationary.</p>
<p>A boat trip in rocky seas or a car trip on winding roads means our head and body will be moving in unusual ways, in two or more axes at once, while sensing accelerations, decelerations and rotations. Together these are strong stimuli to bring on an attack of motion sickness.</p>
<h2>Motion sickness is common</h2>
<p><a href="https://www.bmj.com/content/343/bmj.d7430.long">Around 25-30% of us</a> travelling in boats, buses or planes will suffer – from feeling a bit off all the way to completely wretched; pale, sweaty, staggering, and vomiting.</p>
<p>Some people are extremely susceptible to motion sickness, and may feel unwell even with minor movements such as “head bobbing” while snorkelling, or even <a href="https://www.theatlantic.com/health/archive/2015/02/the-mysterious-science-of-motion-sickness/385469/">riding a camel</a>.</p>
<p><a href="https://www.bmj.com/content/343/bmj.d7430">Susceptibility</a> seems to increase with age, while women are more prone to travel sickness than men. There is a <a href="https://www.theatlantic.com/health/archive/2015/02/the-mysterious-science-of-motion-sickness/385469/">genetic influence</a> too, with the condition running in families. It often co-exists with a history of migraines.</p>
<h2>Preventing motion sickness</h2>
<p>Sufferers quickly work out <a href="https://www.aafp.org/afp/2014/0701/hi-res/afp20140701p41-t2.gif">what to avoid</a>. Sitting in the back seat of the car, reading in a car or bus (trains and planes are better), facing backwards in a bus or train or going below deck on a boat in rough conditions are all best avoided if you’re prone to travel sickness.</p>
<p>Medicines that control vomiting (antiemetics) and nausea (anti-nauseants) are the <a href="https://www.bmj.com/content/343/bmj.d7430">mainstay of medicines</a> used for motion sickness and are effective. But as there are unwanted side effects such as drowsiness, it’s reasonable to try behavioural techniques first, or alongside medicines. </p>
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Read more:
<a href="https://theconversation.com/mondays-medical-myth-peanuts-stop-motion-sickness-5669">Monday's medical myth: peanuts stop motion sickness</a>
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<p>More time “on deck”, keeping an eye on the horizon if there’s a significant swell, and focusing on other things (for example looking out for whales) are <a href="https://www.aafp.org/afp/2014/0701/p41.html">good examples</a>.</p>
<p>Desensitisation or habituation also <a href="https://www.aafp.org/afp/2014/0701/p41.html">work for some</a>. For example, increasing experience on the water in relatively smooth conditions in preparation for longer and potentially rougher trips can help.</p>
<p>There tends to be a <a href="https://www.ncbi.nlm.nih.gov/pubmed/25077501">reduction in symptoms</a> after a couple of days at sea. Medicines can then be reduced and even stopped. Symptoms often return when back on dry land, usually for just a day or two.</p>
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<img alt="" src="https://images.theconversation.com/files/271259/original/file-20190428-194627-wl57f7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/271259/original/file-20190428-194627-wl57f7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/271259/original/file-20190428-194627-wl57f7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/271259/original/file-20190428-194627-wl57f7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/271259/original/file-20190428-194627-wl57f7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/271259/original/file-20190428-194627-wl57f7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/271259/original/file-20190428-194627-wl57f7.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">Motion sickness can hit us on boats, as well as planes, trains, buses and in cars.</span>
<span class="attribution"><span class="source">From shutterstock.com</span></span>
</figcaption>
</figure>
<p>Chewing hard ginger has been <a href="https://www.ncbi.nlm.nih.gov/pubmed?term=3277342">claimed to work</a> for naval cadets, but other studies have <a href="https://www.ncbi.nlm.nih.gov/pubmed/2062873">not confirmed</a> its effectiveness.</p>
<p>Some people find wrist bands that provide acupressure to be effective, although when these have been studied in controlled trials, <a href="https://www.bmj.com/content/343/bmj.d7430">the proof is lacking</a>.</p>
<p>Glasses with a built-in horizon to combat motion sickness were <a href="https://patents.google.com/patent/US20190079314A1/en">patented in 2018</a>, so watch this space.</p>
<h2>How medications work</h2>
<p>Travel sickness medications are more effective when taken pre-emptively, so before your journey begins.</p>
<p>Antiemetics and anti-nauseants act on the brain and nervous system. Medicines used to prevent and treat travel sickness most commonly are either sedating antihistamines or anticholinergics. They block the effects of neurotransmitters (molecules that transmit information) such as histamine, acetylcholine and dopamine in our <a href="https://www.sciencedirect.com/science/article/pii/0165017394000049">balance control centres</a>.</p>
<p>But these sorts of medicines are not very specific. That is, they block the effects of acetylcholine and histamine wherever these neurotransmitters act throughout the body. This explains <a href="https://www.aafp.org/afp/2014/0701/p41.html">unwanted side effects</a> such as sedation, drowsiness, dry mouth, constipation and confusion (in older, vulnerable people). </p>
<p>Drowsiness is more likely to reach dangerous levels if other central nervous system depressants are taken at the <a href="https://www.nps.org.au/consumers/understanding-drug-interactions">same time</a>. This includes opioids (morphine, oxycodone, codeine), alcohol, sleeping pills and some antidepressants.</p>
<iframe title="Medicines used to prevent and treat motion sickness" aria-label="Long Table" src="https://datawrapper.dwcdn.net/30Siq/1/" scrolling="no" frameborder="0" width="100%" height="544"></iframe>
<h2>So what’s the best option?</h2>
<p>A <a href="https://www.cochrane.org/CD002851/ENT_scopolamine-for-preventing-and-treating-motion-sickness">comprehensive review</a> of clinical trials in 2011 compared the medicine scopolamine as a preventative with other medicines, placebos, behavioural and complementary therapies.</p>
<p>Most of the 14 studies reviewed were in healthy men serving in the Navy with history of travel sickness. Women have rarely been subjects, and there are no studies in <a href="https://www.nps.org.au/australian-prescriber/articles/preventing-motion-sickness-in-children">children</a>.</p>
<p>Although scopolamine was found to be marginally more effective than the alternatives, there’s not much to go on to recommend one travel medicine over another.</p>
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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>
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</em>
</p>
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<p>If you’re somebody who experiences motion sickness, speak to your doctor or pharmacist. Most medicines for motion sickness are <a href="https://ajp.com.au/news/travel-health-pharmacy/">available over the counter</a>. You may need to try a few different medicines to find the one that works best for you, but always follow dosage instructions and professional advice.</p>
<p>Once motion sickness is established, the only option is to ride it out. Lying down where possible, getting fresh air and focusing on the horizon can all help alongside appropriate medications. Importantly, for prolonged episodes, try to keep your fluids up to avoid dehydration (especially if vomiting occurs). </p>
<p>If you experience motion sickness for the first time, and if it’s associated with a migraine-like headache, you should seek the advice of a doctor to rule out other neurological conditions.</p><img src="https://counter.theconversation.com/content/112861/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andrew McLachlan receives research funding from the NHMRC, research scholarship funding from GSK for a PhD student under his supervision and has previously received (and disclosed) in kind research support from Pfizer and GSK for investigator initiated research projects (in the last 5 years). Andrew serves as an expert on some TGA committees and has received payment for this role.</span></em></p><p class="fine-print"><em><span>Ric Day 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>Motion sickness can make you feel pretty wretched. But there are a few things you can do to try and prevent it, or to treat it once it takes hold.Ric Day, Professor of Clinical Pharmacology, UNSW SydneyAndrew McLachlan, Head of School and Dean of Pharmacy, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1047462018-11-01T21:32:13Z2018-11-01T21:32:13ZPerfectionists more likely to develop bulimia: New research<figure><img src="https://images.theconversation.com/files/243082/original/file-20181030-76411-1yobszz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Perfectionists are rarely satisfied with their performance or appearance and engage in harsh self-criticism when their efforts fall short. Perfectionists are also more likely to develop the eating disorder bulimia nervosa, according to new research.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><p>Bulimia nervosa is a common and life-threatening eating disorder. About 275,000 Canadian girls and women will <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5757497/">have bulimia at some point in their lives</a>. They will <a href="https://www.mayoclinic.org/diseases-conditions/bulimia/symptoms-causes/syc-20353615">eat large amounts of food, often secretly, and then prevent weight gain</a> by vomiting, fasting or exercise. </p>
<p>Most sufferers of bulimia are female. About two per cent of them die every decade. And around a fifth of those deaths about <a href="https://www.ncbi.nlm.nih.gov/pubmed/22644309">are due to suicide</a>. Uncovering the multiple factors leading to bulimia nervosa is therefore very important, especially as the causes are largely unknown.</p>
<p>As a professor in Dalhousie University’s department of psychology and neuroscience, <a href="https://www.dal.ca/faculty/science/psychology_neuroscience/faculty-staff/our-faculty/simon-sherry.html">I research personality traits and eating disorders</a>. As a clinical psychologist, I also assess and treat eating disorders and associated problems, including perfectionism.</p>
<p>My lab just published the most complete <a href="https://doi.org/10.1016/j.paid.2018.09.022">research study</a> investigating the link between the personality trait of perfectionism and bulimia nervosa to date. Our results clearly show perfectionists have higher odds of developing bulimia and are at greater risk for developing the disease as time passes. </p>
<p>Building on this research, therapists may be able to improve treatments for some bulimic clients by focusing on their underlying perfectionism as well as their symptoms. </p>
<h2>Harsh self-criticism</h2>
<p>Perfectionism involves striving relentlessly for flawlessness and holding unrealistically high standards for oneself and others. </p>
<p>Perfectionists are rarely satisfied with their performance and <a href="https://www.guilford.com/books/Perfectionism/Hewitt-Flett-Mikail/9781462528721/authors">engage in harsh self-criticism when their efforts fall short of perfection</a>.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/243083/original/file-20181030-76390-1mx9e24.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/243083/original/file-20181030-76390-1mx9e24.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/243083/original/file-20181030-76390-1mx9e24.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/243083/original/file-20181030-76390-1mx9e24.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/243083/original/file-20181030-76390-1mx9e24.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/243083/original/file-20181030-76390-1mx9e24.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/243083/original/file-20181030-76390-1mx9e24.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">Perfectionism is linked to relationship problems, disconnection and sadness.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
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<p>To get a more comprehensive picture of whether perfectionism leads people to develop bulimia nervosa, we conducted a thorough literature search that identified 12 longitudinal studies involving a total of 4,665 participants. </p>
<p>We then analyzed results from these 12 studies using statistical means. Most of our participants were female (86.8 per cent) and included adolescents, undergraduates and adults from the community, with an average age of 19 years.</p>
<p>We showed perfectionism predicted increases in bulimia nervosa, even after controlling for baseline levels of the condition. This suggests perfectionists are at risk for developing more bulimia nervosa as time passes. </p>
<p>In fact, our results indicate perfectionism is centrally important to the personality of people who go on to develop bulimia.</p>
<p>Previous research has already shown that external pressure from family, friends and media can contribute to the disease by <a href="https://www.ncbi.nlm.nih.gov/pubmed/11835293">fostering a desire to attain an “ideal” weight and shape</a>. But the link between perfectionism and bulimia has never before been extensively explored.</p>
<h2>A dog-eat-dog world</h2>
<p>Perfectionism is linked with <a href="https://www.ncbi.nlm.nih.gov/pubmed/22353007">relationship problems and feeling sad</a>. Perfectionists may turn to food to cope with sadness brought on by their lack of connection to other people. </p>
<p>Symptoms of bulimia (e.g., binge eating) may also offer perfectionists a <a href="http://dx.doi.org/10.1037/a0037939">temporary escape from pressure and self-criticism</a>.</p>
<p>It’s a dog-eat-dog world today. We have controlling and hyper-competitive helicopter parents. And in society at large, <a href="https://www.ncbi.nlm.nih.gov/pubmed/29283599">self-interest and winning are emphasized</a>. Rank and performance matter more than ever. These are conditions where perfectionism is likely to develop. So, we may see more and more perfectionism-linked cases of bulimia nervosa emerge.</p>
<p>Our results suggest treating perfectionism as early as possible may help to stop the development of bulimia nervosa. It is time to go beyond entirely symptom-focused treatments. Building on our research, clinicians may want to assess and to treat both bulimic symptoms (e.g., vomiting) and underlying perfectionism (e.g., self-criticism).</p>
<p>Bulimia nervosa usually <a href="https://www.ncbi.nlm.nih.gov/pubmed/16791852">lasts for more than eight years before symptoms go away</a>. About 25 per cent of people with the condition develop <a href="https://www.ncbi.nlm.nih.gov/pubmed/19884225">chronic, hard-to-treat symptoms that last for many years</a>. And <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6034764/">affected people often develop other problems</a> such as tooth decay and depression. </p>
<p>Clearly, more research is needed to understand and defeat this disease.</p><img src="https://counter.theconversation.com/content/104746/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Simon B. Sherry receives funding from the Social Sciences and Humanities Research Council of Canada. He owns CRUX Psychology, a private practice in clinical psychology. </span></em></p>Perfectionists have a higher chance of developing bulimia nervosa. Rather than treating symptoms of binge eating and vomiting, therapists should address this underlying personality trait.Simon Sherry, Clinical Psychologist and Professor in the Department of Psychology and Neuroscience, Dalhousie UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/467092016-12-12T03:38:03Z2016-12-12T03:38:03ZWhen nausea from pregnancy is life-threatening<figure><img src="https://images.theconversation.com/files/105342/original/image-20151210-7463-18w1o4i.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="http://www.shutterstock.com/pic-293488796/stock-photo-female-patients-were-treated-with-saline-and-stay-in-front.html?src=b5N0I12-Gul6kQRQrXthOg-1-19">Woman with IV image via www.shutterstock.com.</a></span></figcaption></figure><p>Most women experience some type of morning sickness during pregnancy, but some women develop a far more serious condition.</p>
<p>Hyperemesis gravidarum (HG), which causes severe nausea and vomiting during pregnancy, affects as many as <a href="https://www.acog.org/-/media/For-Patients/faq126.pdf">3 percent of pregnancies</a>, leading to over <a href="http://www.ajog.org/article/S0002-9378(11)01851-5/fulltext">167,000 emergency department</a> visits each year in the U.S.</p>
<p>Until intravenous hydration was introduced in the 1950s, it was <a href="https://www.ncbi.nlm.nih.gov/pubmed/4877794">the leading cause of maternal death</a>. Now, it is the <a href="https://www.ncbi.nlm.nih.gov/pubmed/12100809">second leading cause</a>, after preterm labor, of hospitalization during pregnancy. </p>
<p>And yet, the disease is neither well-understood nor well-known, even with the flurry of headlines when it was announced that the Duchess of Cambridge during her pregnancies <a href="http://www.theguardian.com/uk-news/she-said/2014/sep/27/hyperemesis-gravidarum-kate-middletons-ongoing-condition-is-much-worse-than-just-morning-sickness">suffered from the condition</a>. </p>
<p>I decided to start researching HG in 1999 after losing a baby at 15 weeks of gestation due to constant violent vomiting. I found that there was surprisingly little research on this disease. </p>
<p>To date, I’ve been contacted by over 4,400 pregnant women worldwide and have collected extensive survey data and saliva samples from women with HG and their unaffected friends. Analysis of these data has enabled me to answer some of the most pressing questions about the disease. </p>
<h2>How is this different from morning sickness?</h2>
<p>Even though HG is prevalent, many women don’t know about it until they experience it themselves. Symptoms can include extreme nausea and vomiting, as well as rapid weight loss, dehydration, electrolyte imbalance, dizziness and excessive saliva. Some women may start to vomit blood or bile and may require intravenous fluids and medication. </p>
<p>Some of the women I have encountered in my research on HG experience vomiting so violent that their retinas have detached, their ribs have fractured, their eardrums have burst, their esophagi have torn, their fingernails have fallen off and in rare cases, they can suffer from brain damage from malnutrition. </p>
<p>HG cannot be controlled by small frequent meals and saltine crackers – common recommendations for women with morning sickness. HG can also last for much longer than morning sickness.</p>
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<img alt="" src="https://images.theconversation.com/files/121284/original/image-20160504-19847-169q0c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/121284/original/image-20160504-19847-169q0c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/121284/original/image-20160504-19847-169q0c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/121284/original/image-20160504-19847-169q0c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/121284/original/image-20160504-19847-169q0c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/121284/original/image-20160504-19847-169q0c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/121284/original/image-20160504-19847-169q0c.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">HG can have consequences for mother and child.</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-334218644/stock-photo-a-pregnant-girl-doing-on-ultrasound-examination.html?src=klsCYM6qCxtb7ndcoDcfNQ-2-74">Pregnant women ultrasound image via www.shutterstock.com.</a></span>
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<p>The old wives’ tale that the baby gets everything it needs from the mother even if she is unable to eat or drink or take vitamins is false. </p>
<p>Population studies of neural tube defects and animal studies, as well as studies of human offspring born during famine, in addition to those exposed to HG, now prove that malnutrition in early pregnancy can be linked to long-term health consequences in the exposed fetus. </p>
<p>Children exposed to HG in utero have a three-fold increased risk of <a href="http://dx.doi.org/10.1016/j.ejogrb.2015.03.028">neurodevelopmental delay</a>. Research shows early symptoms of HG were linked to delay, which suggests early vitamin and nutrient deficiencies may be at play.</p>
<p>For <a href="http://dx.doi.org/10.1016/j.ejogrb.2013.04.017">women with HG</a> there is a four-fold increased risk of adverse outcomes, such as preterm birth, and a <a href="http://dx.doi.org/10.1017/S2040174411000249">3.6-fold increased lifetime risk</a> of emotional disorders, such as depression and anxiety. </p>
<p>The effects of HG can <a href="https://www.ncbi.nlm.nih.gov/pubmed/27460690">last long after birth</a>. In one survey we found a significant increased risk of chronic postpartum symptoms in women with HG including reflux, anxiety, depression, insomnia, fatigue and muscle pain, and 18 percent experienced the full criteria of <a href="http://dx.doi.org/10.3109/14767058.2011.582904">post-traumatic stress symptoms</a>.</p>
<p>And HG can also lead to Wernicke’s Encephalopathy (WE), a severe neurological condition caused by a deficiency in thiamin (vitamin B1). Over a dozen cases were <a href="https://www.ncbi.nlm.nih.gov/pubmed/24701066">published in the medical literature between 2012-2014</a>, and recently maternal deaths caused by complications from HG including Wernicke’s Encephalopathy <a href="http://scientonline.org/open-access/mortality-secondary-to-hyperemesis-gravidarum-a-case-report.pdf">have been documented in the U.S., England and Africa</a>. </p>
<p>In a survey of over 800 women with HG, more than <a href="http://dx.doi.org/10.1016/j.contraception.2007.08.009">one in seven women with HG decided</a> to terminate the pregnancy, primarily because they had no hope for relief from the condition.</p>
<h2>How is HG treated?</h2>
<p>Accurate data about what drugs can treat HG effectively and safely are hard to come by. This is due, in part, to the thalidomide disaster of the 1950s, when the drug was prescribed to women with HG to relieve symptoms of nausea and babies were born with limb deformities. This led to difficulty in developing and testing medications on pregnant women.</p>
<p>So what do the limited available data say? A study I conducted with colleagues found that antihistamine use to treat HG has been linked to <a href="http://dx.doi.org/10.1016/j.ejogrb.2013.04.017">preterm birth</a>. We also found that Ondansetron (Zofran) is effective in treating HG symptoms for more than 50 percent of the women in our studies. We have also found that potentially serious side effects in women taking the drug, such as <a href="http://dx.doi.org/10.1016/j.reprotox.2015.07.071">intestinal obstructions</a>, are rare. In recent research, we found <a href="http://dx.doi.org/10.1016/j.reprotox.2016.04.027">no evidence to support a link</a> between ondansetron and birth defects.</p>
<p>But we do know this: Women with HG who are losing weight in pregnancy, and are unable to tolerate food or vitamins for more than a week, should be treated not only with fluids but also with thiamin to avoid the rare but preventable progression to WE, as well as maternal or fetal death. </p>
<p>Caretakers, family members and patients themselves may lean toward termination of a wanted pregnancy rather than try a medication of unknown safety. So for women with HG, seeking treatment can be a fraught experience. </p>
<p>A centralized, national database to document cases of HG, treatments and medications and their effectiveness, and maternal and child outcomes could help us figure out which medications are safe and effective in treating HG. This would increase patient and provider confidence about using treatments during pregnancy. It would also reduce the risk of malpractice or class action suits, which make drug companies and doctors hesitant to test and prescribe new treatments. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/121283/original/image-20160504-17469-iq55rq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/121283/original/image-20160504-17469-iq55rq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/121283/original/image-20160504-17469-iq55rq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/121283/original/image-20160504-17469-iq55rq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/121283/original/image-20160504-17469-iq55rq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/121283/original/image-20160504-17469-iq55rq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/121283/original/image-20160504-17469-iq55rq.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">We need more - and better - research to treat HG.</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-310309151/stock-photo-pregnant-woman-sitting-on-bed-holding-belly.html?src=xtU8OxjZOTYoYgJlzpDfEQ-1-88">Pregnant woman via www.shutterstock.com.</a></span>
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<h2>We need to know what causes HG to treat it</h2>
<p>Years of research, primarily focusing on hormones, have failed to identify what causes HG, and consequently, a clinically proven safe and effective treatment has yet to be found. </p>
<p>Currently, the leading hypothesis is that pregnancy hormones cause nausea and vomiting, and genetic and environmental factors that influence susceptibility to nausea and vomiting may turn normal pregnancy nausea into hyperemesis. </p>
<p>Increasing evidence suggests a genetic component to HG. If a woman has HG during one pregnancy there is about an <a href="http://dx.doi.org/10.1111/j.1542-2011.2010.00019.x">80 percent risk of recurrence</a> in a subsequent pregnancy. The risk of recurrence is not affected by <a href="http://dx.doi.org/10.3109/14767058.2011.632039">change in partner</a> or <a href="http://www.ncbi.nlm.nih.gov/pubmed/25345812">psychiatric factors</a>. The greatest risk factor for HG (besides having a previous HG pregnancy) is having a sister with HG, which constitutes <a href="http://dx.doi.org/0.1016/j.ajog.2010.09.018">a 17-fold increased risk</a>.</p>
<p>A common misconception is that if a woman is the only one in her family with HG, it is not genetic. However, our research suggests the gene or genes responsible are <a href="https://dx.doi.org/0.1016/j.ajog.2010.09.018">equally likely to be passed from</a> the paternal line as the maternal line. In <a href="https://dx.doi.org/10.1016/j.mce.2016.09.017">a recent study</a> of five families with a history of HG, we found a gene that signals vomiting in two of them. In addition, HG may be caused by a combination of several genes. A woman with HG may be the only one in her family with a pregnancy history that carries a particular combination of predisposing genes. </p>
<p>Once we identify the genetic and associated biological causes of HG, further research will likely help us develop therapies that target these causes of the condition, rather than blindly and rather ineffectively treating symptoms.</p><img src="https://counter.theconversation.com/content/46709/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Marlena Schoenberg Fejzo has received funding from and is a science advisor for the Hyperemesis Education and Research Foundation (HelpHer.org). </span></em></p>Hyperemesis gravidarum causes severe nausea and vomiting during pregnancy. Even though it affects up to 3 percent of pregnancies, research about its causes and treatments is sparse.Marlena Schoenberg Fejzo, Associate Researcher in Medicine, University of California, Los AngelesLicensed as Creative Commons – attribution, no derivatives.