HIV incidence among men who have sex with men (MSM) and transgender women in sub-Saharan Africa is “alarmingly high,” according to research presented to the recent HIV Research for Prevention conference (HIVR4P) in Madrid. The study was conducted at sites in Kenya, Malawi and South Africa and found an overall incidence rate of 6.96 per 100 per-person years of follow-up, meaning that each year 7% of participants acquired a new HIV infection.
Incidence was especially high among participants recruited in Cape Town, South Africa. Presence of a rectal sexually transmitted infection (STI) at enrolment was the key risk factor for HIV seroconversion.
The results show that HIV prevention interventions targeted at MSM and transgender women need to be intensified, say the international team of investigators.
Sex between men is criminalised in most sub-Saharan African countries and is also highly stigmatised. HIV prevalence among MSM in sub-Saharan Africa is very high, usually far exceeding that observed in the general population. However, little is known about HIV incidence among MSM and transgender women in this setting.
The HPTN 075 study provided an opportunity to address this research gap.
The primary aim of this prospective, multi-country study was to assess the feasibility of recruiting and retaining MSM in HIV prevention research. The present analysis was designed to determine HIV incidence and its risk factors, and involved MSM and transgender women recruited at two sites in South Africa (Cape Town and Soweto) and one site each in Kenya (Kisumu) and Malawi (Blantyre).
The aim was to recruit 100 individuals at each study site.
Recruitment criteria included biological male sex at birth, age between 18 and 44 years, and anal sex with a man in the previous three months. Men with prevalent HIV infection at baseline were eligible for recruitment, but numbers were limited to 20 individuals at each study site. Participants were recruited in collaboration with local community groups. Use of informal networks, such as peer outreach and referral, was common across all four sites.
At screening, participants were asked about their sexual behaviour and were screened for rectal STIs (chlamydia and gonorrhoea). Follow-up lasted 12 months, during which participants were tested regularly for HIV.
HIV prevalence was high (30%) among individuals who were screened for participation. Approximately a fifth (18%) of the final study population was HIV positive. A total of 329 HIV-negative individuals were recruited.
The mean age was 24 years and 53% of the participants were employed. A significant proportion (16%) identified as transgender or female. Most (56%) said they were sexually attracted to both men and women, 61% reported ever having had sex with a woman, but 60% identified as gay.
In terms of HIV risk factors, a rectal STI was diagnosed in 16% of participants at the screening visit. Taking the sample as a whole, the mean number of incidents of receptive and insertive anal intercourse without a condom in the previous three months was 1.39 and 1.30, respectively. The mean number of unprotected receptive and insertive anal intercourse partners was 0.29 and 0.31, respectively. The investigators acknowledge that these numbers seem very low, but stressed they were for the entire study sample, including men who reported no condomless anal sex.
The 329 HIV-negative participants contributed a total of 301 person-years of follow-up. During this time, 21 individuals seroconverted for HIV, an incidence of 6.96 per 100 person-years of follow-up.
Incidence varied considerably between sites:
- Malawi, 1.34 per 100 person-years
- Kenya, 3.75 per 100 person-years
- Soweto, 8.97 per 100 person-years
- Cape Town, 14.44 per 100 person-years.
The investigators note that that these differences reflected local HIV prevalence.
Univariate analysis identified several significant risk factors for incident HIV infection. Not unsurprisingly, these were number of occasions of receptive anal sex without a condom (HR = 1.04; 95% CI, 1.01-1.06 < 0.001), number of condomless receptive anal sex partners (HR = 1.83; 95% CI, 1.08-2.10, p = 0.024) and a rectal STI at enrolment (HR = 3.95; 95% CI, 1.66-9.38, p = 0.002).
After controlling for potential confounders, the only significant risk factor was a diagnosis with a rectal STI at the time of enrolment (HR = 2.68, 95% 1.06-6.80, p = 0.038).
The investigators found the HIV incidence among the study participants alarmingly high, especially because the rate of new HIV infections across the general population in sub-Saharan Africa is declining. The researchers believe that HIV prevention for MSM and transgender women needs to be intensified, stressing that interventions should be carefully tailored to address the differing needs of MSM and transgender women. The results also point to the need to remove structural barriers to health care and health promotion, especially laws criminalising sex between men.