HIV-1 infection in young men in northern Thailand.

OBJECTIVES: To determine risk factors for HIV-1 infection in young men in northern Thailand. METHODS: At enrollment into a prospective study, data were collected from a self-administered questionnaire and serologic testing on a cohort of 1115 young men selected by lottery for conscription. RESULTS: The overall HIV-1 infection rate was 6.9%; however, the rate was 15.3% among the 387 (34.7%) men who had been living in the upper north subregion of Thailand compared with 2.5% for the remaining 728 men (P < 0.001). A history of sex with female prostitutes was reported by 74.7% of men and increased frequency of this type of sex was highly associated with HIV-1 infection and a history of sexually transmitted disease (STD) symptoms (chi 2 for trend, P < 0.001). In stratified and multivariate analyses, however, history of STD symptoms, reported by 42.5% of the cohort, was most strongly associated with HIV-1 infection. Only 42.8% of men who reported sex with prostitutes had used condoms more than half the time. CONCLUSIONS: Young men in the general population in northern Thailand are at high risk for HIV-1 infection via sex with female prostitutes; STD are highly associated with HIV-1 infection. Increasing condom use and controlling STD should be immediate goals of HIV control programs.

PIP: This study sought to determine risk factors for HIV-1 infection in young men in northern Thailand. This cohort of 1115 young men were selected by lottery for conscription and at enrollment into this prospective study, data were collected from a self-administered questionnaire and serologic testing. The overall HIV-1 infection rate was 6.9%; however, the rate was 15.3% among the 387 (34.7%) men who had been living in the upper north subregion of Thailand compared with 2.5% for the remaining 728 men (p 0.001). A history of sex with female prostitutes was reported by 74.7% of men and increased frequency of this type of sex was highly associated with HIV-1 infection and a history of sexually transmitted disease (STD) symptoms (chi square for trend, p 0.001). In stratified and multivariate analyses, however, history of STD symptoms, reported by 42.5% of the cohort, was most strongly associated with HIV-1 infection. Only 42.8% of men who reported sex with prostitutes had used condoms more than half the time. Young men in the general populations in northern Thailand are at high risk for HIV-2 infection via sex with female prostitutes; STDs are highly associated with HIV-2 infection. Increasing condom use and controlling STD should be immediate goals of HIV control programs.

Probability of female-to-male transmission of HIV-1 in Thailand.

The epidemic of human immunodeficiency virus type 1 (HIV-1) infection in Thailand has allowed an estimate to be made of the probability of female-to-male HIV-1 transmission per sexual contact. In a study of 1115 21-year-old male military conscripts, of whom 77 (6.9%) were HIV-1 seropositive, sex with female prostitutes was identified as the principal mode of HIV-1 transmission. With a mathematical model including data on conscript's age at first sexual contact, frequency of sex with female prostitutes, and province of origin; as well as province-specific HIV-1 seroprevalence of prostitutes, we estimated the probability of HIV-1 transmission per sexual contact to be 0.031 (95% confidence limits [CL] 0.025-0.040). Allowing for random error in the self-reported frequency of contacts, the estimate was 0.056 (95% CL 0.041-0.075). The transmission probability was significantly greater among men with a history of sexually-transmitted diseases. These estimates are substantially higher than analogous estimates made in North America. This high per-act probability of heterosexual transmission helps to explain the rapid spread of HIV-1 in the emerging epidemic in Thailand and perhaps in other countries where HIV-1 transmission is predominantly heterosexual.

PIP: Approximately 75% of the estimated 13 million HIV-1 infections in adults worldwide are the result of heterosexual intercourse. Epidemiological investigations in Thailand suggest that sex with female prostitutes is the principal mode by which young men contract HIV. Sex with nonprostitute women, sex with men, IV drug use, blood transfusion, and tattooing have not appeared in augment the risk of infection. This study reports findings from a study conducted to determine the probability in Thailand of female-to-male transmission of HIV-1 per sexual contact. 1115 male military conscripts, aged 21 years of whom 6.9% were HIV-1 seropositive, were subjects of the study. Sex with female prostitutes was identified as the principal mode of HIV transmission among these young men. None of the 46 men who reported engaging in receptive anal intercourse was HIV-seropositive. Data on conscript's age at first sexual contact, frequency of sex with female prostitutes, province of origin, and province-specific HIV-1 seroprevalence of prostitutes was put to a mathematical model designed to produce an estimate of transmission probability. The probability of female-to-male transmission of HIV-1 per sexual contact was estimated to be 0.031 under 95% confidence limits. Allowing for random error in the self-reported frequency of contacts yielded a higher probability of 0.056. Transmission probability was significantly higher among the 43% of men who reported histories of STDs. Circumcision was very uncommon among these men who were 98% Buddhist. These estimates are substantially higher than comparable ones produced in studies in North America.

Herpes in the time of AIDS: a comparison of the epidemiology of HIV-1 and HSV-2 in young men in northern Thailand.

OBJECTIVES: To compare the epidemiologic pattern of HIV-1, a recently introduced sexually transmitted disease (STD) agent in Thailand, with the pattern of HSV-2, a well-established STD agent, so that future trends for both viruses can be better understood. METHODS: We obtained questionnaire data and determined HSV-2 (by specific gG-2) and HIV-1 seroreactivity in a cohort of 1,115 young male army conscripts who entered service in northern Thailand in 1991. RESULTS: Seroprevalence of HIV-1 and HSV-2 was 6.9% and 14.9%, respectively. For HSV-2-seropositive men who reported previous genital ulcers, HIV-1 seroprevalence was 32%. For most variables, there was a close correspondence between the prevalence ratios for HIV-1 and for HSV-2, except that prevalence ratios for HIV-1 tended to be greater than the corresponding ratios for HSV-2. The seroprevalence of both viruses was strongly related to early and frequent contact with female sex workers (FSWs), infrequent use of condoms with FSWs, and residence in the upper north region of Thailand. When differences in sexual behavior between the upper north and lower north were controlled for, the seroprevalence of both viruses still differed significantly by region. CONCLUSIONS: Although the seroprevalence levels of HSV-2 and HIV-1 were quite different in this cohort of Thai army conscripts in 1991, the patterns of infection in terms of demographic, residential, and behavioral variables were similar. Seroprevalence studies of HSV-2 in other populations, particularly where the HIV-1 epidemic is just beginning, may be useful in predicting which subgroups might be most vulnerable to the epidemic and could therefore benefit the most from public health intervention. Where differences in the patterns of the two viruses have been noted, we hypothesize that the pattern for HIV-1 will evolve toward that seen for HSV-2.

PIP: Herpes simplex virus type 2 (HSV-2) has been in Thailand longer than has been HIV-1. The epidemiology of the 2 viruses was compared in an attempt to gain insight into likely future trends of the dissemination of HIV-1 and HSV-2 in the country. Findings are based upon questionnaire and serostatus data on a cohort of 1115 young male army conscripts who entered service in northern Thailand in 1991. The 1061 conscripts were 21 years old and the remainder were 22-27 years old. 879 were unmarried, 598 were farmers, and 55 were students. 6.9% of the young men were infected with HIV-1 and 14.9% with HSV-2. Among HSV-2-seropositive men who reported previous genital ulcers, HIV-1 seroprevalence was 32%. For most variables, there was a close correspondence between the prevalence ratios for HIV-1 and HSV-2, except that prevalence ratios for HIV-1 tended to be greater than the corresponding ratios for HSV-2. The seroprevalence of both viruses was strongly related to early and frequent contact with female prostitutes, infrequent condom use with such prostitutes, and residence in the upper northern region of Thailand. The patterns of infection were similar for the 2 viruses, suggesting the direction in which HIV-1 seroprevalence levels will go.

Sexual behavior of young men in Thailand: regional differences and evidence of behavior change.

An anonymous, self-administered behavioral survey was conducted in Royal Thai Army (RTA) conscripts from 19 provinces throughout Thailand in May 1996. All (to a maximum of 350) Thai men who entered the RTA in each province were selected. Data from 5474 men were included in this analysis. High-risk behaviors were reported nationwide; however, some regional differences were found. Men from the upper North were more likely to have had a commercial sex worker (CSW) as their first sexual partner (42%) than men from any other region. However, in the past year, reported sex with CSWs in the upper North (41%) was similar to or lower than those in other regions. Consistent condom use with CSWs was higher in the North than in any other region. Condom use at first sex with CSWs increased with later years at first sex in all regions. These data suggest that past higher-risk behavior among young men in the upper northern part of Thailand may have contributed to the concentration of the HIV epidemic in that region. Risk behaviors, particularly unprotected sex, appear to be decreasing nationwide.

PIP: The HIV behavioral risk factors associated with temporal and regional trends in HIV prevalence were investigated in a 1996 survey of 5474 Royal Thai Army conscripts from 19 provinces. 89% of respondents were 21 years of age and 77% were single. HIV prevalence was highest among men from the upper north (4.3%), followed by 2.6% in the central region, 2.4% in Bangkok, and 1.2% in the southeast. The median age at first intercourse was 17 years. Among sexually experienced men, a significantly higher proportion of those from the upper north (42%) had their first such encounter with a commercial sex worker (CSW). However, sex with CSWs during the year preceding the survey was similar or less frequent among men from the upper north (41%) compared with other regions. Also, significantly more men from the upper north (62%) used condoms every time with a CSW. Overall, 10% (range, 8-12%) reported having had sex with a man and 13% reported symptoms of a sexually transmitted disease (STD). Men whose sexual initiation occurred after 1990 were more likely to use condoms with a CSW partner. The decrease in sexual risk factors documented in this survey is consistent with national declines in HIV prevalence, especially in the upper northern region, after 1992. The increase in condom use with CSWs coincides with the 100% condom campaign initiated in 1991, intensified STD control efforts, and the emergence of AIDS deaths. Sex with non-CSW female partners, where condoms are rarely used, and homosexual sex require attention as situations where HIV risk may persist.

AIDS awareness among a cohort of young Thai men: exposure to information, level of knowledge, and perception of risk.

Structured interviews and focus group discussions were conducted among 834 young Thai men drafted into military service by random lottery in northern Thailand. Level of AIDS risk, exposure to AIDS information, level of knowledge about AIDS, and perception of risk for acquiring HIV and AIDS were assessed at baseline and six months after induction into the Army in 1991. General fear of AIDS was high, yet personal perception of risk for acquiring HIV was low, even for those at enhanced behavioural risk of infection with HIV. Multivariate PATH analysis shows that exposure to information about AIDS significantly reduced risk taking from baseline to follow-up, but only by first affecting personal risk perception. Focus group discussions revealed that risk perception for acquiring AIDS was low due to never knowing a person with AIDS, because prostitutes had health certificates for STD, and since many believed that AIDS could be cured or prevented with folk medicines. Implications and recommendations for intervention programmes are discussed.

HIV-1 subtype E incidence and sexually transmitted diseases in a cohort of military conscripts in northern Thailand.

OBJECTIVES: To determine the rate of and risk factors for HIV-1 seroconversion and describe sexually transmitted disease (STD) prevalence rates for young men in northern Thailand. METHODS: Data were collected from self-administered questionnaires and serologic testing at enrollment in a prospective study in 1991 and at follow-up after 6, 17, and 23 months on a cohort of 1115 men selected by lottery for military conscription. RESULTS: A total of 14 men seroconverted to HIV-1 envelope subtype E. The overall HIV-1 incidence rate was 1.1 (95% confidence interval [CI], 0.6-1.8) per 100 person-years (PY) of follow-up. However, the rate was 2.0/100 PY for conscripts from the upper northern subregion of Thailand compared with 0.5/100 PY from other regions (adjusted rate ratio [RR] = 2.69; 95% CI, 0.8-12.2). On multivariate analyses, the behavioral factors associated with HIV-1 seroconversion were frequency of sex with female sex workers (FSWs; p = .04), receptive anal sex (adjusted RR = 6.73; 95% CI, 1.8-21.7), and large amount of alcohol consumption (adjusted RR = 3.12; 95% CI, 1.0-10.9). Genital ulceration was the STD most strongly associated with seroconversion. The prevalence of serologic reactivity to syphilis, Haemophilus ducreyi, and herpes simplex virus type 2 increased with greater frequency of sex with FSWs and was generally higher for men from the upper north. CONCLUSION: Young men in northern Thailand are at high risk for HIV-1, primarily through sex with FSWs; and other STDs are highly associated with HIV-1 incidence. As HIV-1 infection extends into the general population, intervention programs are needed to address the problem of sexual transmission apart from commercial sex venues.

PIP: Findings are presented from a prospective study conducted to determine the rate of and risk factors for HIV-1 seroconversion, and to describe sexually transmitted diseases (STD) prevalence rates for young men in northern Thailand. Study findings are based upon data collected from self-administered questionnaires and serologic testing at enrollment in 1991 and at follow-up after 6, 17, and 23 months on a cohort of 1115 young men chosen by lottery for military conscription. Men in Thailand are generally eligible for conscription in the year of their 21st birthday. 6.9% of the men were HIV-1 seropositive at enrollment; 15.3% of men from the upper northern region compared with 2.5% of men from elsewhere. 14 subjects seroconverted to HIV-1 envelope subtype E over the course of the study. The overall HIV-1 incidence rate was 1.1/100 person-years (PY) of follow-up. However, the rate was 2.0/100 PY for conscripts from the upper northern subregion of Thailand compared with 0.5/100 PY from other regions. Multivariate analyses found frequent sex with female prostitutes, receptive anal sex, and high levels of alcohol consumption to be positively associated with HIV-1 seroconversion. Genital ulceration was the STD most strongly associated with seroconversion. The prevalence of serologic reactivity to syphilis, Haemophilus ducreyi, and herpes simplex virus type 2 increased with greater frequency of sex with female prostitutes, and was generally higher for men from the upper north.