Growing evidence suggests hepatitis C can be transmitted sexually

The hepatitis C virus, normally thought to be transmitted exclusively through blood — such as by sharing of needles among intravenous drug abusers — can also be transmitted through sexual activity, principally through anal sex among gay men, a growing body of evidence suggests. The most recent evidence was reported Thursday by New York City researchers who documented an outbreak of the virus, commonly known as HCV, among gay men.

Hepatitis C, which can cause severe liver disease and even death if left untreated, affects an estimated 3.2 million Americans. Many infected people show no symptoms, but others have severe disease that can require liver transplants. The infection can be cured in most people with a combination of the drugs pegylated interferon alpha and ribavirin, plus a recently approved drug called Incivek, but treatment is most successful when started early in the course of the disease.

Dr. Daniel Fierer, an infectious diseases expert at the Mount Sinai School of Medicine, and his colleagues first observed two cases of HCV that they believed to be caused by sexual transmission in late 2005. They requested referrals of similar patients. The team reported Thursday in the Centers for Disease Control and Prevention’s Morbidity and Mortality Weekly Report that they found a total of 74 cases. All the men reported having receptive anal sex and none had any other risk factors for HCV, such as intravenous drug abuse. When the team compared the infected men to other gay men who were not infected with the virus, they found that those who became infected were 23 times more likely to have had unprotected gay sex and 29 times more likely to have had anal sex while using crystal methamphetamine. Moreover, genetic analysis showed that there were five separate clusters of the virus, indicating that the virus was getting transmitted through groups of interconnected men.

“While hepatitis C is not sexually transmitted among stable heterosexual couples, this is clearly not the case among HIV-infected [men having sex with men] in New York City,” Fierer said in a statement. Such men, “and to some extent their healthcare providers, are generally not aware that having unprotected receptive sex can result in HCV infection .... Our study suggests that HIV-infected [gay men] should take steps to protect themselves and others by using condoms and by avoiding crystal methamphetamine.”