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Nov. 3, 2006 -- Drug users who get hepatitishepatitis C but manage to fight off the infection seem to be protected from future infections with the liver-killing virus.
That finding comes from a study of more than 3,500 drug users in Vancouver, Canada. Sharing needles during injection drug use is by far the most common way people get hepatitis C.
University of British Columbia researchers Jason Grebely, Mark W. Tyndall, MD, ScD, and colleagues tested more than 2,000 of the drug users for hepatitis C antibodies. They did not include anyone who had undergone treatment for the virus.
The antibody test, which shows whether a person has ever had hepatitis C, was negative for 926 drug users and positive for 1,143.
Sophisticated tests on 658 of the hepatitis-C-positive drug users showed that 506 had persistent infection -- but that 152 had somehow rid themselves of active virus.
Also, this "spontaneous clearance" of hepatitis C virus seemed to partially protect these drug users against new infections. Despite continuing drug use, they were four times less likely to get a new hepatitis C infection.
"Our data lend support to the hypothesis that previous exposure to hepatitis C virus may be protective ? despite repeated exposure [to the virus]," Grebely and colleagues conclude.
This does happen in chimpanzees. Chimps that fight off hepatitis C virus get significant protection against future infection. And when they do get infected, they don't get severe disease.
Grebely and colleagues note that current hepatitis C treatment allows more than half of patients to essentially clear the virus from their bodies.
If treatment-related clearance works like spontaneous clearance, such treatment might protect against future infection.
That could lead to a big change in treatment policy.
Currently, doctors hesitate to give the expensive and difficult-to-endure treatment to people who are still using illicit drugs.
But, "As injection drug users continue to drive the hepatitis C epidemic in developed countries, it is quite clear that any efforts to control this epidemic must include a comprehensive strategy to address the disease in this target population," Grebely and colleagues argue.
"[The study] could provide a stronger rationale for expanding treatment programs for injection drug users -- including those who continue to be at risk for hepatitis C exposure," they say.
The study appears in the November issue of Hepatology.
SOURCES: Grebely, J. Hepatology, November 2006; vol 44: pp 1139-1145.