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.