This article by Roger Pebody first appeared on aidsmap.com here.
A small study assessing the infectiousness of HIV-positive gay men taking antiretroviral therapy has found that all study participants had an undetectable viral load in the rectum. Men who had rectal gonhorroea or chlamydia didn’t have detectable virus either, suggesting that concerns about sexually transmitted infections raising the risk of HIV transmission may be unfounded when people are taking effective HIV treatment.
The data were presented to the British HIV Association conference in Brighton yesterday.
It has long been thought that untreated sexually transmitted infections can raise HIV viral loads. For example, the ‘Swiss Statement’, and its British equivalent have both advised that the protective impact of HIV treatment on onward transmission may not apply if either partner has a sexually transmitted infection. However, the interim results of the PARTNER study found no HIV transmissions at all from gay men taking HIV treatment although 16% of the cohort had sexually transmitted infections while in the study.
The new data specifically concern rectal viral loads and rectal sexually transmitted infections. There are conflicting data on how high viral loads in rectal secretions are. A detectable rectal viral load would increase the risk of HIV transmission during anal sex without a condom when the man living with HIV is ‘bottom’.
Researchers at Guy’s and St Thomas’ Hospitals in London recruited 42 men who have sex with men living with HIV who were having sexual health check-ups.
21 were taking antiretroviral therapy, including seven who had asymptomatic rectal gonorrhoea or chlamydia.
21 had never taken antiretroviral therapy, again including seven who had asymptomatic rectal gonorrhoea or chlamydia.
Rectal swabs were tested for sexually transmitted infections, HIV viral load and ten inflammatory cytokines. (It’s hypothesised that inflammation could raise the risk of HIV transmission.)
In all men taking antiretrovirals, rectal viral loads were undetectable (below 100 copies/ml). This included the seven men with rectal gonorrhoea or chlamydia, both before and after antibiotic treatment.
In men who hadn’t used antiretrovirals, rectal viral loads were a median 2 log10 lower than their plasma viral loads. Having a sexually transmitted infection didn’t raise rectal viral loads or markers of inflammation, which were at similar levels to those taking antiretrovirals.
The findings suggest that gonorrhoea and chlamydia have a minimal impact on onward HIV transmission, the researchers say.
Davies O et al. Impact of rectal gonorrhoea and chlamydia on HIV viral load and inflammatory markers in the rectum; potential significance for onward transmission. BHIVA conference, Thursday 23 April 2015, abstract O19. (Presentation slides available here).