Sexual transmission of hepatitis C virus (HCV) is considered rare. But a new study by researchers at Mount Sinai School of Medicine, working with the Centers for Disease Control and Prevention (CDC), provides substantial evidence that men with HIV who have sex with other men (MSM) are at increased risk for contracting HCV through sex.

The results of the study are published in today's edition of the CDC's Morbidity and Mortality Weekly Report.

HCV transmission primarily occurs through exposure to blood, and persons who inject drugs at greatest risk. But when Mount Sinai researchers observed a large increase in the number of new cases of HCV transmission among HIV-infected men who did not inject drugs, they took a closer look to examine the role of sexual transmission among these men.

The researchers identified 74 HIV-infected men between October 2005 and December 2010 who had documented new HCV infection and yet reported no other risk factor for HCV infection, including injection drug use. When they compared 22 of these men with a control group of 53 closely matched HIV-infected MSM who did not have HCV infection, they found that the men who had recently contracted HCV were 23 times more likely to have had unprotected anal sex with men. In addition, HCV genetic analysis suggested that HCV was transmitted within social networks of these men, consistent with the presence of a city-wide epidemic.

"While hepatitis C is rarely transmitted among stable heterosexual couples, this is clearly not the case among HIV-infected MSM in New York City," said Dr. Daniel Fierer, Assistant Professor of Medicine and Infectious Diseases at Mount Sinai School of Medicine. "MSM, and to some extent their health care providers are generally not aware that having unprotected receptive sex can result in HCV infection. The good news is that the cure rate for new HCV infections is very high with early treatment, but without regular testing of the men at risk, these largely asymptomatic infections may be missed and this opportunity lost."

"Our study suggests that HIV-infected MSM should take steps to protect themselves and others by using condoms. Also, health care providers should be screening these men for hepatitis C, and public education and outreach programs should include information about these risks," Dr. Fierer concluded.

Source: Mount Sinai School of Medicine