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Target IV drug users early to stop hepatitis C

Each IV drug user contracting hepatitis C likely to infect around 20 people with the virus, study suggests

Ingrid Torjesen

Friday, 01 February 2013

Each intravenous drug user contracting Hepatitis C is likely to infect around 20 other people with the virus, and half of these transmissions will occur in the first two years after the user is first infected, a study published in PLOS Computational Biology estimates.

The researchers suggest that early diagnosis and treatment of hepatitis C in IV drug users could prevent many transmissions by limiting the impact of these 'super-spreaders'.

Working out 'who has infected who' in fast-spreading diseases such as influenza is often relatively straightforward, but in slow-spreading diseases such as hepatitis C and HIV, it is extremely difficult. But a new approach, developed by a team from Oxford University, University of Athens and Imperial College, combines epidemiological surveillance and molecular data to describe in detail, for the first time, how hepatitis C spreads in a population.

The research draws on data from four hepatitis C epidemics in Greece, using information on 943 patients in treatment studies between 1995 and 2000, and around 100 genetic sequences representative of the epidemic taken from frozen plasma samples collected between 1996 and 2006. The team used a mathematical model to estimate the variance of secondary infection and how long it takes for such infection to occur.

Dr Gkikas Magiorkinis of Oxford University's Department of Zoology and lead author of the study, said: “For the first time we show that super-spreading in Hepatitis C is led by intravenous drug users early in their infection. Using this information we can hopefully soon make a solid argument to support the scaling-up of early diagnosis and antiviral treatment in drug users. Helping these people and stopping the spread of Hepatitis C is our ultimate target.”

The World Health Organization has identified Hepatitis C as a major public health problem: up to 180 million people worldwide live with the virus, most are unaware that they have been infected and remain undiagnosed for more than 10 years. Unlike other forms of Hepatitis there is currently no vaccine available, although there are effective treatments. The only significant transmission route for hepatitis C is now intravenous drug use.

"Working out how many people are likely to be infected by each 'super-spreader' of Hepatitis C, as well as how soon they will be infected, has been a puzzle for over 20 years," said Dr Magiorkinis. "Our research has resolved this issue and paves the way for a modelling study to show what kind of public health interventions could really make a difference. Our approach should also be very useful to those studying HIV."

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