A study of gay and bisexual men diagnosed with recently acquired hepatitis C infection and treated in three English clinics has found that 40% of them were HIV negative, the 25th Annual Conference of the British HIV Association (BHIVA) was told in Bournemouth this week, though all the HIV-negative men were in London.
Daniel Bradshaw of Public Health England said the HIV-negative men were on average younger and had a higher average number of sex partners than HIV-positive men with hepatitis C; 81% were using pre-exposure prophylaxis (PrEP) or had done in the last year.
This study adds to recent evidence from France and the Netherlands that PrEP may be associated with changes in sexual risk behaviour and the epidemiology of sexually transmitted infections. Historically, hepatitis C that is sexually transmitted – or rather, associated with sex, as sharing of drug injection equipment during ‘chemsex’ may also transmit infection – has been almost exclusively seen in HIV-positive gay men. So much so, that it was hypothesised that only HIV-positive people were susceptible to hepatitis C infection. An international review showed that the annual incidence of hepatitis C in HIV-positive men rose fivefold from 0.32% in 1990 to 1.6% in 2015; in contrast, it rose non-significantly from 0.04% to 0.08% in HIV-negative men over the same period.
The study looked at all gay and bisexual men who were diagnosed with recently acquired hepatitis C (infected in the previous year) who were referred to three hepatitis clinics in London, Brighton and Leeds between January and August 2017.
The total number referred was 40. Of these 16 (40%) were HIV negative and 24 (60%) HIV positive.
The HIV-negative men were significantly younger (average age 34) than the positive men (average age 44) and had had a significantly higher number of condomless anal sex partners in the last year (36 versus 16). All attended the London clinic whereas seven out of 24 (29%) of the positive men were in Brighton or Leeds.
Thirteen of the 16 HIV-negative men (81%) were using PrEP or had done in the last year. Of the HIV-positive men, 22 out of 24 (92%) had an undetectable viral load.
Apart from this, the characteristics of the positive and negative men were quite similar. About 30% of both groups were diagnosed with another sexually transmitted infection (STI) at the same time as hepatitis C.
In both groups, 45% had injected drugs, 35% had done so in the last year, and a third had had the experience of being injected by another person. For all but one of the men, the last drug they had injected was methamphetamine.
As well as having significantly more condomless anal sex partners, the negative men scored more highly on other sexual risk measures – 88% had had group sex and 75% had engaged in fisting, compared to 71% and 54% for HIV-positive men, though these differences were not statistically significant.
Few men think their partners have hepatitis C
The men were asked about the HIV and hepatitis C status of their sexual partners over the last year. Specifically, “Are all, most or some of your partners HIV positive/HIV negative/of unknown status?”. A similar question was asked about hepatitis C.
The HIV-negative men were just as likely to know or believe that at least some of their partners had HIV as the HIV-positive ones – 81% versus 83%. In fact only 69% knew or believed that all, most or some of their partners did not have HIV – this suggests that over 30% could not confidently report that any of their sex partners were HIV negative, though 69% reported that they had had at least some partners whose HIV status they did not know.
As for the HIV-positive men, 58% reported that at least some of their partners did not have HIV, and 54% reported partners of unknown status, though these are figures may be under-reported due to perceived social undesirability.
The situation with hepatitis C was very different. While 69% of HIV-negative and 50% of HIV-positive men reported that at least some of their partners were of unknown hepatitis C status, only 25% of HIV-negative and 12.5% of HIV-positive men reported that “some, most or all” of their partners did have hepatitis C. In other words, 75% of negative men and 87.5% of positive men could not point to any partner in the last year they knew had hepatitis C, even though they had caught it themselves.
In some ways this is not that surprising. There is no PrEP for hepatitis C – so people are less likely to willingly have sex with someone who has it, and people with it may be less likely to disclose. And people are less often tested so may not know their status anyway.
However, it does suggest that gay men, HIV-positive and negative alike, who engage in high risk sexual practices are underestimating the likelihood of partners having hepatitis C and may not be discussing it.
Clusters and superclusters
Phylogenetic analysis of the men’s hepatitis C viruses along with those of other previously diagnosed individuals found seven clusters of hepatitis C infections ranging from two transmission pairs to one cluster with 27 members. Winding back the genetic ‘clocks’ – the speed at which mutations happen within related viral strains – found that the seven strains had points of origin – i.e. had a point at which they started to diversify from each other – between 1973 and 2001, with a concentration of diversity in the 1990s, contemporaneous to the HIV epidemic.
However, it also found that the clinic samples divided into two ‘superclusters’ that were so different; their diversity pointed to a date of divergence of around 1930, showing that hepatitis C has been in the UK and specifically in London for at least that long. Three clusters had no members who said they had injected drugs, showing that hepatitis C viruses could circulate within exclusively sexually transmitting networks for years.