Repeat offender: the strange comings and goings of hepatitis C

In the developed world, people who regularly inject drugs are most at risk of being infected with hepatitis C. AAP

Hepatitis C is a blood-borne virus that infects about 3% of the world’s population. It’s a significant cause of both illness and death due to cirrhosis (advanced liver scarring) and liver cancer.

By the end of 2007, an estimated 204,000 Australians had a chronic infection from the hepatitis C virus.

Given the large number of people living with hepatitis C in Australia, it’s important that we work with high-risk people in a way that makes them active participants.

Community-based research

Our research is a community-based project with an on-going cohort of 400 people who regularly inject drugs. This group is most at risk of infection.

We’ve been following these people regularly since 2005 – interviewing them and providing testing for hepatitis.

At the start of the project, we found that about half had already been exposed to hepatitis C. And almost one in three people still required a vaccination for hepatitis B.

Referring such people to health-care providers who can have them vaccinated is an important aspect of our work as this sub-group may not often see health-care workers.

Our field research team regularly re-interviews research participants as well as testing and counselling them for blood-borne virus transmission and prevention.

Findings

To date, our work shows that people who inject drugs are being infected with hepatitis C more frequently than previously assumed; that many carry multiple strains of the virus; and the type of hepatitis C someone has can vary and change over time.

We’ve also found that some people remain free of hepatitis C infection despite risky behaviour with infected associates.

Our ability to intensively study the immune functioning of these individuals holds promise for hepatitis C vaccine development.

The most important thing we’ve found so far is that a proportion of people exposed to the virus are able to clear it. And that some of these people can actually become infected again.

This is one of the big differences between hepatitis C and hepatitis B. Most people infected with the latter who clear the virus cannot become infected again.

How the immune system of this smaller sub-group responds is important because they indicate our prevention efforts alone won’t reduce infection rates and that current anti-viral treatments aren’t the solution.

By using this cohort, we’ve been able to explore specific research questions such as incident infection with hepatitis C; alcohol consumption and living with HCV; and participant experiences of overdose, initiation into drug treatment and experiences of recent incarceration.

And like researchers the world over working in this area, our focus is to do what we can to lower the burden of disease and costs resulting from hepatitis C.

Infection

In developed countries, people who inject drugs are at greatest risk of hepatitis C; in Australia, over 80% of the estimated 9,700 new hepatitis C infections every year are due to injecting drug use.

Other potential sources of HCV transmission include tattooing and body piercing, blood product (prior to the introduction of hepatitis C testing in 2002) and mother to child transmission.

Symptoms

The vast majority of people (85%) don’t have symptoms when they are first infected with hepatitis C.

Of those who develop chronic infection – defined as persistent virus in the blood after six months – many remain symptom free or have minor or moderate symptoms such as malaise, nausea, abdominal pain and general flu like symptoms.

After 20 years of living with the hepatitis C virus, about 7% will develop cirrhosis with a small percentage leading to liver cancer.

Testing

There are two major tests used to detect if someone has been exposed to hepatitis C (anti-HCV antibody) and has ongoing infection in the blood (HCV ribonucleic acid).

A positive anti-HCV antibody test only measures if a patient has ever been exposed to HCV – it doesn’t necessarily mean they have on-going infection.

Patients with a positive anti-HCV antibody test should have a HCV RNA test to check for on-going infection.

Unfortunately, a number of general practitioners mistakenly believe a positive anti-HCV antibody differentiates between current and resolved infection and are not aware that both tests needed.

There are six different hepatitis C genotype and the two most common ones in Australia are genotype one and genotype three. Checking the genotype is important because it influences the length of required treatment.

Treatment

HCV treatment has advanced over the past ten years leading to improved outcomes. And two new therapies are likely to be available in Australia in late 2012.

Response to treatment varies – genotype one requires 48 weeks of treatment and genotype three requires 24 weeks.

Despite improvement in treatment outcomes, the uptake of therapy remains low. The total number being treated in Australia annually is around 4000 individuals.

Over the next five years – with changes in medication, improved testing of a person’s early response to treatment and knowledge of the genetic marker predicting response to treatment – the length of treatment is likely to reduce and the chances of treatment success to increase.

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