Men who have sex with men (MSM) living with HIV in San Diego have been contracting hepatitis C virus (HCV), likely often through sex, at a rising rate for the past 15 years, aidsmap reports.

The increase is particularly notable among those who do not inject drugs but who use crystal meth. A worrisome rate of HIV-positive men who are cured of HCV are subsequently reinfected with the virus.

Researchers conducted two retrospective studies of HIV-positive MSM who attended the largest HIV clinic in San Diego. The study first looked at data from 2000 to 2015 on 2,396 men who had an initial negative HCV test. Seven percent of the men reported ever injecting drugs; 59 percent said they had ever used meth.

The results of both studies were presented at the Annual Meeting of the American Association for the Study of Liver Diseases (AASLD) in Boston.

A total of 149 of the men tested positive for HCV during a cumulative 12,560 years, for an infection rate of 1.19 percent per year.

Eighteen percent of those newly infected with hep C reported injecting drugs, compared with 7 percent of those who were HCV negative. A respective 82 percent and 58 percent reported using meth.

Among those who reported injection drug use, the hep C infection rate was 2.6 percent per year, compared with 0.97 percent per year among those who did not report such drug use. The respective infection rates for those who did and did not report meth use was 1.53 and 0.52 percent per year.

Looking at the entire cohort, the researchers found that the hep C infection rate increased from 0.36 percent per year between 2000 and 2003 to 1.52 percent per year between 2012 and 2015. While the infection rate rose slowly among those who did not inject drugs, the rate rose steeply among meth users.

The researchers also conducted a retrospective analysis of 1,092 HIV-positive men at the San Diego clinic who initially tested HCV negative between 2008 and 2016.

Forty of the men eventually tested positive for HCV, during a cumulative 3,440 years, for an infection rate of 1.16 percent per year.

Forty-three men at the clinic were cured of HCV between 2008 and 2015. Twenty-nine of them remained in care while 14 were lost to follow-up, moved or died. Three of the men who remained in care were reinfected with HCV, during a cumulative 104 years of follow-up among the overall group of men cured. This translated to a reinfection rate of 2.89 percent per year. Two of the men who were reinfected said they had shared drug injection equipment, while the third man did not; he presumably recontracted HCV through sex.

To read the aidsmap article, click here.

To read the HCV infection rate study abstract, click here.

To read the HCV reinfection study abstract, click here.