HIV Prevalence Among Populations of Men Who Have Sex with Men --- Thailand, 2003 and 2005

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In 2003 and 2005, the Thailand Ministry of Public Health -- U.S. Centers for Disease Control and Prevention Collaboration and its partners conducted surveillance of human immunodeficiency virus (HIV) prevalence and risk factors among populations of men who have sex with men (MSM) in Thailand. In 2003, the assessment was conducted in Bangkok among a sample of MSM* (1). In 2005, in addition to Bangkok, the assessment was conducted in Chiang Mai and Phuket provinces, and participants were categorized as MSM, male sex workers (MSW), or transgendered persons (TG). This report compares HIV prevalence among MSM in Bangkok during 2003 and 2005, reports HIV prevalence among the three populations in 2005, and summarizes the results of univariate and multivariate analysis of risk factors for HIV infection in 2005. The results indicated a significant increase in HIV infection among MSM in Bangkok from 2003 to 2005. The findings also indicated that in 2005, HIV infection was widespread among MSM, MSW, and TG in the three study locations. Moreover, the following risk factors were independently associated with HIV infection: being recruited from Bangkok or Chiang Mai (MSM), older age (MSM and TG), being recruited from a park or street location (MSW and TG), drug use (MSM), self-reporting a history of sexually transmitted infections (MSW), and self-reporting a previous HIV-positive test result or refusing to disclose a previous HIV test result (MSM and MSW). Sex with women during the preceding 3 months was inversely associated with HIV prevalence among MSW. More effective behavioral and biomedical interventions for MSM, MSW, and TG are needed to stop the spread of HIV in these populations.

Using venue-day-time sampling^† (1,2), participants were enrolled from locations where MSM, MSW, and TG congregate to socialize and seek sex partners and clients, including entertainment venues (e.g., bars and discos), parks, saunas, street locations, and sex-work venues (e.g., "go-go" bars [i.e., bars where sex workers can be solicited] and massage parlors). Venues and participants were selected by using a systematic process of mapping and visiting venues, enumerating attendance at different times and days, and determining eligibility of participants and their willingness to participate (1,2). To participate, a person had to be Thai, male at birth, a resident of the study area, and aged >15 years (>18 years for the 2003 study) and had to have engaged in anal or oral sex with a man during the preceding 6 months. Participation was voluntary and anonymous, and oral informed consent was required. In 2003, an interviewer-administered questionnaire was used, and in 2005, a self-administered questionnaire was used to collect demographic and behavioral information, which was completed using handheld computers. Oral fluid specimens were collected using the OraSure^® device and tested at a 1:2 dilution in single wells by an enzyme immunoassay (EIA). Positive samples were retested in duplicate, and two or more positive wells were reported as oral fluid anti-HIV positive (1). Oral HIV test results were available to participants who, if determined to be HIV positive, were referred for confirmatory EIA serum testing and appropriate HIV treatment and care according to Thai national guidelines (3).

In 2003, a total of 1,121 Thai MSM were enrolled from 14 venues in Bangkok (enrollment rate: 90.2%) (1); in 2005, a total of 2,049 Thai men were enrolled from 106 venues in Bangkok, Chiang Mai, and Phuket (enrollment rate: 97.3%). Of the latter sample, 821 were categorized as MSM, 754 as MSW, and 474 as TG.

In Bangkok, the overall HIV prevalence among MSM increased from 17.3% (95% confidence interval [CI] = 15.1%--19.7%) in 2003 to 28.3% (95% CI = 23.9%--33.0%) in 2005 (Figure). A statistically significant increase (p<0.05; assessed by c² test) in HIV prevalence in Bangkok was observed among MSM at entertainment venues and saunas and in all age groups. In 2005, in Bangkok, 22.3% of MSM aged 15--22 years, 30.5% of MSM aged 23--28 years, and 29.7% of MSM aged >29 years were infected with HIV.

In 2005, the HIV prevalence among MSM was 15.3% in Chiang Mai and 5.5% in Phuket (Table). In 2005, the HIV prevalence among MSW was 18.9%, 11.4%, and 14.4% in Bangkok, Chiang Mai, and Phuket, respectively. HIV prevalence among TG was 11.5%, 17.6%, and 11.9% in Bangkok, Chiang Mai, and Phuket, respectively. HIV prevalence among MSM differed significantly among the three study areas (c²_df=2 = 47.67; p<0.001); no such differences were observed among MSW and TG.

In 2005, among MSM, the following factors were significantly associated with HIV prevalence in univariate analysis: residing in Bangkok or Chiang Mai, older age, recruitment from an entertainment venue or sauna, homosexual or bisexual self-identification, both insertive and receptive anal intercourse, self-reported genital ulcer or discharge (ever), self-reported drug use (ever), refusal to disclose a previous HIV test result, and a self-reported previous HIV-positive test result.^§ Sex with women during the preceding 3 months was inversely associated with HIV infection (Table). In multivariate analysis, residing in Bangkok or Chiang Mai, older age, drug use, and refusal to disclose a previous HIV test result were significantly and independently associated with HIV infection.

Among MSW, recruitment from a park or street location, self-identification as homosexual or gay, receptive or both insertive and receptive anal intercourse, self-reported genital ulcer or discharge, and a self-reported previous HIV-positive test result were significantly associated with HIV infection in univariate analysis. Sex with women during the preceding 3 months was inversely associated with HIV infection. In multivariate analysis, recruitment from a park or street location, self-reported genital ulcer or discharge, and a self-reported previous HIV-positive test result were significantly and independently associated with HIV infection; sex with women during the preceding 3 months was inversely associated with HIV infection.

Among TG, older age, recruitment from a park or street location, lower education, history of selling sex, and a higher number of sex partners during the preceding 3 months were significantly associated with HIV infection in univariate analysis. In multivariate analysis, older age, being recruited from a park or street location, and lower education were significantly and independently associated with HIV infection.

Reported by: F van Griensven, PhD, A Varangrat, MSc, W Wimonsate, MSc, JW Tappero, MD, C Sinthuwattanawibool, MSc, JM McNicholl, MD, PA Mock, MAppStat, Thailand Ministry of Public Health -- U.S. Centers for Disease Control and Prevention Collaboration; T Siraprapasiri, MD, Dept of Disease Control, Thailand Ministry of Public Health, Nonthaburi; P Phanuphak, MD, AIDS Research Centre, Thai Red Cross Society; R Jommaroeng, MSc, Rainbow Sky Assoc of Thailand, Bangkok; S Visarutratana, PhD, Chiang Mai Provincial Health Office, Chiang Mai; T Netwong, MD, P Utokasenee, Phuket Patong Hospital, Patong, Thailand. RA Jenkins, PhD, G Mansergh, PhD, C Toledo, PhD, Div of HIV/AIDS Prevention, National Center for HIV, Viral Hepatitis, STDs, and Tuberculosis Prevention (proposed), CDC.

Editorial Note:

Twenty years after Thailand's first AIDS case was reported in a young homosexual man (4), Thai MSM, MSW, and TG remain at high risk for HIV infection. HIV prevalence is especially high among MSM aged 15--22 years. Because these MSM have been sexually active for a brief period, the HIV prevalence in this group suggests a high underlying HIV incidence.

The increase in HIV prevalence in Bangkok MSM cannot be explained by differences in the methodology of the two surveys; sampling, specimen collection, and testing methods were the same. Moreover, with the exception of the decreased age threshold (15 years in the 2005 survey versus 18 years in the 2003 survey), eligibility criteria also were identical. The mean age of participants in both surveys was the same (27 years). Sample size calculation determined that 399 MSM were enrolled for the study in Bangkok during 2005. Before the 2003 assessment, data on HIV prevalence among MSM were unavailable; thus, 1,121 MSM were enrolled to allow estimation of a wide range of possible prevalences with a 95% degree of confidence and to have sufficient cell sizes for detailed statistical analysis.

Risk factors for HIV infection in the assessment were similar to those previously identified (5). Sex with women was independently associated with a lower risk for HIV infection among MSW. This finding might be attributed, in part, to the fact that the majority of MSW (62.9%) in the survey identified themselves as nonhomosexual, with nearly all of these (84.4%) reporting that they did not engage in receptive anal intercourse, the practice associated with the highest risk for HIV infection (5). Another factor might be the low HIV prevalence among women in Thailand, making heterosexual acquisition of HIV less likely. In 2005, HIV prevalence among pregnant women attending public antenatal care facilities in Thailand was 1.0% (6). Injection-drug use was low in the study population, suggesting that among MSM, MSW, and TG in Thailand, HIV is predominantly transmitted sexually. Nevertheless, analysis of the 2005 data indicates that lifetime use of any noninjected drug (mostly smoked methamphetamine) was reported frequently by MSW (38.5%), TG (24.1%), and MSM (15.5%). The use of drugs, particularly those that are injected or enhance or prolong sexual pleasure, among MSM, MSW, and TG in Thailand needs further monitoring because drug use patterns might change over time.

The results of this analysis also indicate lack of awareness of current HIV status in the study population, particularly among those who were HIV positive. Of the 340 men who tested HIV positive in the 2005 survey, 274 (80.6%) reported that they were HIV negative or that they had never been tested for HIV infection. Of these 274 men, 57 (20.8%) received their first HIV-positive test result as part of this assessment. Overall, of 2,049 participants, 511 (24.9%) returned for their HIV test results, of whom 64 (12.5%) were HIV positive. All 64 men were referred for confirmatory EIA serum testing and HIV treatment and care, including immunologic evaluation (CD4 cell count) to determine eligibility for highly active antiretroviral therapy (HAART) and antimicrobial prophylaxis and treatment, according to Thai national guidelines (3). To decrease and prevent HIV risk behaviors (7), MSM, MSW, and TG in Thailand should be encouraged to get tested for HIV infection more frequently (8) so that they can take measures to protect themselves and their partners from HIV infection.

The findings in this report are subject to at least three limitations. First, the study population consisted of men who were present at venues where MSM, MSW, and TG congregate to socialize and find sex partners or clients. Men who do not attend these venues might have different HIV risk factors and HIV prevalence. Second, men with higher risk for HIV infection might have attended multiple venues and might have enrolled in the study more than once, thereby inflating HIV prevalence estimates. This possibility is unlikely, however, because data-collection periods were brief (approximately 2 weeks), and travel among venues is uncommon in Bangkok. Moreover, MSW and TG typically worked and lived at the venue where they enrolled, making their enrollment at another venue improbable. Finally, men who attend venues frequently might have a higher HIV prevalence and were more likely to be included in the assessment, thereby inflating HIV prevalence estimates. However, no association between venue attendance and HIV prevalence was determined; thus, the data were not weighted for frequency of attendance.

The high HIV prevalence among MSM, MSW, and TG in Thailand, as documented in this report, highlights the need for more effective behavioral and biomedical interventions to prevent the spread of HIV in these populations at high risk. Interventions should include programs to reduce sexual risk behavior, promotion of more frequent voluntary HIV counseling and testing, and improved services for diagnosis and treatment of sexually transmitted infections.

This report is based, in part, on contributions by S Naorat, MA, T Guadamuz, MHS, P Akarasewi, MD, C Kittinunvorakoon, PhD, P Wasinrapee, MSc, S Kurachit, MA, B Jumtee, N Tippanont, T Chemnasiri, W Thienkrua, Thailand Ministry of Public Health -- U.S. Centers for Disease Control and Prevention Collaboration; S Thanprasertsuk, MD, P Sirivongrangson, MD, Dept of Disease Control, Thailand Ministry of Public Health, Nonthaburi; S Tantipaibulvut, A Jamrasrak, P Chuariyakul, AIDS Research Centre, Thai Red Cross Society; K Kanggarnrua, D Linjongrat, P Chanlearn, Rainbow Sky Assoc of Thailand, Bangkok, Thailand.

^§ Because nearly all Thai men are uncircumcised, circumcision was not evaluated as a possible risk factor for HIV infection.

HIV Prevalence Among Populations of Men Who Have Sex with Men --- Thailand, 2003 and 2005

Editorial Note:

References