The hepatitis C virus (HCV) diagnosis rate among men who have sex with men (MSM) in an ongoing Truvada (tenofovir disoproxil fumarate/emtricitabine) as pre-exposure prophylaxis (PrEP) study in Amsterdam is as high as the rates seen in previously reported cohorts of HIV-positive MSM, aidsmap reports. Among those HIV-negative men in the Dutch study who were cured of HCV, one in four were reinfected with the virus annually.

In recent years, Western nations have seen a rising epidemic of sexually transmitted hep C among HIV-positive MSM in particular. There have also been reports of HIV-negative men contracting HCV, including those on PrEP; but until now, the infection rates seen among MSM without HIV have always been considerably less than those seen in their HIV-positive counterparts.

Research has suggested that HIV itself may facilitate sexual transmission of HCV, possibly helping to explain the HIV-status-based disparity in sexually transmitted hep C among MSM. That said, researchers have also theorized that the phenomenon of serosorting, in which MSM seek to avoid HIV transmission by tending to have sex with partners of the same HIV status, has helped to isolate the sexually transmitted hep C epidemic among HIV-positive MSM.

Now, the advent of PrEP as well as greater public knowledge about antiretroviral (ARV) treatment’s awesome power to prevent people with HIV from passing on the virus are helping to break down more than three decades of sexual barriers between HIV-negative and -positive men. So it is possible that hep C is increasingly spreading from the HIV-positive MSM population into the HIV-negative MSM population.

The Amsterdam PrEP demonstration project (AmPrEP) began in August 2015 and is slated to run through the end of 2020. It recruited 374 MSM and two transgender women and provided them the option of either taking daily PrEP or following the on-demand dosing protocol in which Truvada is taken only in the days surrounding sex.

Findings from an analysis of hep C diagnosis rates among the cohort covering August 2015 to December 2017 were presented at the International AIDS Conference in Amsterdam (AIDS 2018). Most of the participants were involved in the study for the entire period.

The AmPrEP participants receive HCV testing twice yearly. Upon their entry into the study, 4.8 percent of the participants tested positive for the virus.

Twelve participants were diagnosed with hep C through the end of the period analyzed, which translated to about a 1 percent annual infection rate. Nine, or 75 percent, of them reported engaging in chemsex, which is a European term for engaging in sex while taking any from a list of drugs, including crystal meth. The 12 men reported an average of 19 anal sex partners during the three months prior to testing positive for HCV and an average of eight partners with whom they were the receptive partner (the bottom) and whom they did not previously know.

The study authors conducted genetic analyses of the participants’ hep C and found evidence that these viruses belonged to various local transmission clusters that each included both HIV-positive and HIV-negative men. This finding lends credence to the theory that HCV infections may be set to rise among HIV-negative MSM compared with their HIV-positive counterparts in an era when serosorting is declining.

Six of the 12 men diagnosed with HCV during follow-up were previously cured of the virus, which gave the cured group a reinfection rate of 25.5 percent per year. This reinfection rate is considered extraordinarily high.

To read the aidsmap article, click here.