HIV and Syphilis Infection Among Men Who Have Sex with Men – Bangkok, Thailand, 2005-2011

Published: June 28, 2013

Although efforts to control the heterosexual human immunodeficiency virus (HIV) epidemic in Thailand had shown success by the late 1990s (1), HIV continued to spread in other risk groups, including men who have sex with men (MSM). In 2003, the Thailand Ministry of Public Health–U.S. CDC Collaboration (TUC) started surveillance among MSM in Bangkok, finding an HIV prevalence of 17.3% (2). By 2005, HIV prevalence in this group had risen to 28.3% and has since stabilized at around 30% (2,3). To obtain additional information about HIV and sexually transmitted infection (STI) prevalence and incidence in a clinic-based population of MSM, TUC, in collaboration with the Thai Red Cross AIDS Research Center, analyzed data collected at the Silom Community Clinic (SCC), an HIV and STI testing center targeting MSM. This report describes trends in HIV and syphilis prevalence and incidence seen among SCC MSM clients during 2005–2011. At first clinic visit, the prevalence of HIV infection among 4,762 clients was 28.3% and of syphilis (all stages) was 9.8%. Among those returning for HIV or syphilis testing before the end of 2011, the incidence of HIV infection was 6.3 per 100 person-years (PY) and 3.6 per 100 PY for syphilis. These results show ongoing epidemics of HIV and syphilis infection in MSM in Bangkok, underscoring the urgent need for preventive interventions to reduce the spread of HIV and STI in this population.

The SCC is located in a central Bangkok hospital close to a large number of MSM entertainment venues and was founded by TUC in 2005. It supports an environment and staff receptive to the health and concerns of the MSM community; HIV and STI testing services are free, rapid, anonymous, and confidential. The long-term goal of the SCC is to build a durable relationship with the MSM community and to identify safe, effective, and affordable HIV prevention methods for MSM.

At first visit, all SCC attendees are offered HIV voluntary counseling and testing* and evaluation for primary, secondary, and latent syphilis.† Other procedures offered include testing for immunity to hepatitis A and B,§ hepatitis B vaccination (if eligible), and evaluation for the presence of gonococcal and nongonococcal urethral, pharyngeal, or rectal infections; genital ulcers; and warts. All testing, vaccination, and STI treatments are provided free of charge. Since July 2009, HIV-negative clients have been offered nucleic-acid amplification testing for acute HIV infection. Reactive nucleic-acid amplification testing in HIV antibody-negative persons is evidence of acute HIV infection, a phase of infection during which viral replication and infectiousness are high (4). All HIV-positive SCC attendees are offered a CD4+ T lymphocyte count¶ to assess their eligibility for antiretroviral therapy (ART)** and antimicrobial treatment. Thailand offers free public health care to all its citizens, and HIV ART was included in 2006 (5). HIV and syphilis prevalence were calculated at the first SCC visit during 2005–2011 when this testing was performed. HIV and syphilis incidence were computed among those who tested negative for HIV or syphilis at first visit, who returned for testing later. Times between the date of the first negative test and the midpoint between the dates of the last negative and first positive HIV or syphilis test were used to calculate PY of follow-up time. Trends in HIV prevalence and incidence were evaluated for statistical significance using chi-square and Poisson exact tests.

During the 2005–2011 period, 4,762 MSM clients made a total of 15,219 visits to the SCC (Table). Most (60.9%) clients were aged <30 years, 90.8% were Thai, 7.2% were non-Asian, and 2.0% were other Asian. Almost all (91.8%) resided in the Bangkok metropolitan area. Less than half (42.7%) reported a history of previous HIV testing. The yearly number of clients increased from 221 in 2005 to 1,135 in 2011, and the yearly number of visits increased from 439 to 4,220 during the same period. Prevalence of HIV at first visit during 2005–2011 was 28.3% and of syphilis 9.8%. HIV incidence was 6.3 per 100 PY and of syphilis was 3.6 per 100 PY of follow-up. Of the 2,736 HIV-negative specimens evaluated by nucleic-acid amplification testing since July 2009, 15 tested positive for acute HIV infection (prevalence: 0.55%). Among the 1,243 who tested HIV-positive, 41.9% had a CD4+ count of ≤350 cells/µL, 29.1% had a count of >350 and ≤500 cells/µL, and 29.0% had a count of >500 cells/µL. Although HIV prevalence was significantly higher among older attendees (29.5% among those aged ≥30 years versus 22.8% for those aged ≤21 years), HIV incidence was significantly higher in the younger age group (12.2 per 100 PY for those aged ≤21 years versus 3.2 per 100 PY for those aged ≥30 years) (Table). From 2005 to 2011, significant increases occurred in the annual prevalence of HIV (from 24.6% to 29.4%) and syphilis (from 5.0% to 12.5%). The incidence of HIV also increased significantly from 2005–2006 to 2011, from 2.8 per 100 PY to 7.9 per 100 PY, as did the incidence of syphilis, from 0.0 per 100 PY to 7.1 per 100 PY (Table).
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