Hepatitis C virus infection is rising among gay and bisexual men in San Diego

The prevalence of hepatitis C virus (HCV) infection among HIV-positive men who have sex with men in San Diego has increased over the past 15 years, especially among men who do not inject drugs but use methamphetamine, according to a study presented at the 2016 AASLD Liver Meeting this month in Boston. Another study by the same researchers found that post-treatment reinfection is also a concern in this population.

Starting in the early 2000s researchers in the UK and elsewhere in Europe began reporting clusters of apparently sexually transmitted acute HCV infection among HIV-positive gay and bisexual men in large cities; similar outbreaks followed in cities in Australia and the US. A number of risk factors have been implicated – including condomless anal sex, fisting, group sex, other sexually transmitted infections and non-injection drug use – but these have not been consistent across studies. HCV sexual transmission remains rare among HIV-negative men who have sex with men.

Antoine Chaillon of the University of California at San Diego and colleagues assessed the incidence of HCV infection among men who have sex with men in San Diego. To date, most reports on HCV sexual transmission among gay men in the US have come from New York City and San Francisco.

The researchers did a retrospective cohort analysis of HCV incidence among HIV-positive men who have sex with men attending the UCSD Owen Clinic, the largest HIV clinic in San Diego, between 2000 and 2015.

The analysis included 2396 clinic clients who had a negative HCV antibody test at baseline. The median age was 38 years, 68% were white and 10% were black. Only 7% reported having ever injected drugs, but 59% said they had ever used methamphetamine.

Incident or new infection was defined as a positive HCV antibody or HCV RNA test following a negative test. Participants were tested for HCV a median of three times with a median interval of 1.2 years between tests.

A total of 149 HCV seroconversions occurred during 12,560 person-years of follow-up time, yielding an incidence rate of 1.19 per 100 person-years (95% CI 1.01-1.39). New HCV cases were identified an average of 10.6 years after HIV diagnosis and 3.6 years after the first negative HCV test.

Men with new HCV infection did not differ from the cohort as a whole in terms of age or race/ethnicity. However, the newly infected men were significantly more likely than uninfected men to have injected drugs (18 vs 7%) and used methamphetamine (82 vs 58%).

HCV incidence was significantly higher among men who reported injection drug use compared to those who did not (2.6 vs 0.97 per 100 person-years). Likewise, HCV infection was significantly more common among men who said they used methamphetamine compared to those who did not (1.53 vs 0.52 per 100 person-years).

Overall HCV incidence increased over time, from just 0.36 new infections per 100 person-years between 2000 and 2003, to 1.52 per 100 person-years between 2012 and 2015. New HCV cases among men who did not inject drugs or use methamphetamine rose slowly, while incidence among men who did use methamphetamine rose steeply over time. Incidence among men who injected drugs rose sharply from 2000-2003 to 2004-2007, but then stabilised and declined between 2008-2011 and 2012-2015 – perhaps reflecting an increase in harm reduction practices.

"These findings suggest that HCV incidence is increasing among HIV+ MSM in San Diego," the researchers concluded. "These rates are similar to London and other major European cities, and double that observed in the US Multicenter AIDS Cohort Study."

"This study also documented HCV infection among HIV+ MSM who do not inject drugs and an increased HCV incidence among individuals reporting methamphetamine use," they added. "Further work determining the epidemic trajectory and prevention required to control the epidemic is needed.

HCV reinfection

Dr Chaillon's team also compared the incidence of primary (first-time) HCV infection and reinfection following successful hepatitis C treatment among HIV-positive men who have sex with men in San Diego.

High rates of HCV reinfection following successful treatment among HIV-positive gay and bi men have been reported in Europe, but there is little data on reinfection among gay men in the US, the researchers noted as background.

This retrospective analysis included 1092 HIV-positive men at the Owen clinic who had a negative baseline HCV test between 2008 and 2016.

The researchers identified 40 initial HCV seroconversions over 3440 person-years at risk, giving an overall primary HCV incidence rate of 1.16 per 100 person-years (95% CI 0.85-1.59).

There were 43 men who started hepatitis C treatment between 2008 and the end of 2014 and achieved a sustained virological response (SVR). Their median age was 50 years and most (79%) had HCV genotype 1. Of these, 29 remained in care and were periodically re-evaluated for potential reinfection, while 14 were lost to follow-up, relocated or died.

Of the men who were successfully treated, three became reinfected, defined as a positive HCV RNA test after achieving SVR. Over 103.9 person-years of follow-up, the estimated reinfection rate was 2.89 per 100 person-years, though the confidence interval was wide due to the small numbers (95% CI 0.60-8.44).

Two of the reinfected men reported sharing drug injection equipment, but the third did not report any history of drug use and was assumed to have been reinfected via sex. The reinfected men were younger (median 33 years) than the SVR group as a whole, and all three had well-controlled HIV infection and mild liver fibrosis (stage F1) when initially treated.

All three men were treated with pegylated interferon/ribavirin. Reinfection occurred a median of 2.7 years after SVR. Although these men all had HCV genotype 1 both initially and at the end, relapse is not known to occur this long after successful treatment.

"HCV reinfection incidence among HIV-infected MSM in San Diego is 2-3 fold higher than primary HCV incidence," the researchers concluded. "Although this reinfection rate is lower than observed in European settings among HIV-infected MSM, increased efforts at preventing reinfection post-treatment among HIV-infected MSM are still needed."