A study among injecting drug users in Greece found those who contract Hepatitis C will likely spread the disease to 20 other people – half of them within the first two years of infection.
Although up to 180 million people worldwide carry the hepatitis C virus, only around one in four develop symptoms within the first six months of infection. The rest experience no symptoms and are often not diagnosed for many years. Ultimately around one in five develop cancer or liver scarring (cirrhosis), usually around 20 years after infection, leaving liver transplantation as their only option.
Long delays between infection and diagnosis make it extremely hard to track the path of the disease through populations as it is very difficult to work out who has infected who.
Taking a new approach, researchers from the University of Oxford worked with scientists at the University of Athens and Imperial College London to examine data from 943 patients in Greece, collected between 1995 and 2000 and covering four hepatitis C epidemics.
The study, published in the journal PLOS Computational Biology, used genetic information from 100 representative samples of the virus strain connected to the epidemic, collected between 1996 and 2006. Using computer modelling, the team discovered that injecting drug users were, on average, each transmitting the virus to 20 other people. Crucially, they determined that half of these transmissions occur in the first two years after initial infection.
Dr Gkikas Magiorkinis, a research fellow in the University of Oxford’s Department of Zoology and lead author of the study, said: ‘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. 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.”
He also noted their approach could be applied to other infections, including HIV.
Charles Gore, chief executive of The Hepatitis C Trust and president of the World Hepatitis Alliance, called the study “potentially very important”, saying it could help pave the way for better and more cost-effective “interventions”.
However, he added: “It needs to be said…globally hepatitis C is not ‘a drug users’ disease” adding that “of the 150 million people living with the virus, only about 10 million are people who inject drugs.” Instead Gore blamed “unsafe healthcare” for the majority of infections.