Hepatitis C virus (HCV) has transmitted among gay men since the early days of the AIDS epidemic, with HIV-positive men at much higher risk, particularly those with lower CD4 counts, aidsmap reports. Publishing their findings in the online edition of Clinical Infectious Diseases, investigators from the Multicenter AIDS Cohort Study (MACS) followed 5,310 men who have sex with men (MSM) between 1984 and 2011, all of whom entered the study without hep C.

A total of 4,384 of the men were recruited between 1984 and the early 1990s, with the balance participating in the study between 2001 and 2003. Across the board, 36 percent reported unprotected anal sex (UAI), 5 percent reported injection drug use and 5 percent had chronic hepatitis B (HBV). Thirty-eight percent were HIV positive.

The investigators followed the men for a median of seven years, yielding a total of 55,343 person-years of analysis. The study identified 115 incident hep C infections, for a rate of 2.8 infections per 1,000 person-years. The infection rate for HIV-positive men was over eight times that of HIV-negative men, at 4.22 per 1,000 person-years compared with 0.50 per 1,000 person-years.

After controlling for other factors, including injection drug use and blood transfusions, the investigators found that HIV infection increased the risk of hep C infection 7.56-fold, hep B infection increased the risk 2.12-fold and unprotected receptive anal intercourse with multiple partners raised the risk 4.02-fold. Recent syphilis infection was also associated with increased risk.

Among the HIV-positive men, each increase of 100 CD4 cells, up to a CD4 count of 500, was linked with a 7 percent drop in risk of hep C infection.

To read the study abstract, click here.

To read the aidsmap story, click here.