Preventive intervention to reduce sexually transmitted infections: a field trial in the Royal Thai Army.

BACKGROUND: During 1991 through 1993, sexually transmitted infections among conscripts in the Royal Thai Army in the upper-northern provinces were common: human immunodeficiency virus (HIV) prevalence at induction was 12%, HIV incidence was 2.4% per year, and incidence of sexually transmitted diseases was 17% per year. We evaluated a behavioral intervention to reduce incident sexually transmitted infections among conscripts inducted into the Thai Army in 1993. METHODS: We developed a preventive intervention that addressed consistent condom use, reducing alcohol consumption and brothel patronage, and improving sexual negotiation and condom skills. Companies were assigned to 1 of 3 groups matched on military mission: 450 men were in the intervention group, 681 were in barracks at the same base but did not receive the intervention (diffusion group), and 414 were in distant camps (controls). Baseline HIV serological testing and behavioral interviews were conducted during basic training in 1993. The intervention was applied for 15 months, and men were followed up at 6-month intervals (with repeated HIV serological testing, sexually transmitted disease assessments, and behavioral interviews) through May 1995. RESULTS: Incident sexually transmitted diseases were 7 times less frequent among men assigned to the intervention than the combined controls (relative risk, 0.15; 95% confidence interval, 0.04-0.55), after adjusting for baseline risk factors (P<.005). There was no diffusion of the intervention to adjacent barracks. The intervention decreased incident HIV by 50% in the intervention group. CONCLUSION: Intensive interventions in structured institutions can successfully reduce risk in settings confronting expanding heterosexual HIV epidemics.

Decreasing incidence of HIV and sexually transmitted diseases in young Thai men: evidence for success of the HIV/AIDS control and prevention program.

OBJECTIVE: To determine whether HIV and sexually transmitted disease (STD) incidence rates among young men in northern Thailand have declined since the establishment of the '100% Condom Program', and to prospectively document changes in the association between behavioral risk factors and incident HIV and STD infections. SETTING: Thirteen military bases in northern Thailand. METHODS: Serial prospective cohorts of 19-23-year-old male conscripts (n = 4086) inducted into military service from six northern Thai provinces between 1991 and 1993 were followed at 6-month intervals for incident HIV and STD through May 1995. HIV incidence was determined by serology, and incident STD were reported by conscripts as diagnosed by health-care providers. RESULTS: HIV incidence declined from a rate of 2.48 per 100 person-years during 1991-1993 to 0.55 per 100 person-years during 1993-1995. STD incidence showed an even greater decline, with a 10-fold decrease from 1991-1993 to 1993-1995. Behavioral risk factors for incident STD infections included a history of prior STD and sex with girlfriends and sex workers. Inconsistent condom use remained a strong predictor of incident STD among brothel visitors. Other previously-reported risk factors in 1991-1993 such as illicit drug use, frequency and cost of brothel visits, and low socioeconomic status were not associated with incident STD or HIV in 1993-1995. CONCLUSIONS: Although several studies have recently reported decreased prevalence of HIV and STD infections in Thailand, these data demonstrate that a dramatic decrease in the incidence rates of STD, including HIV infection, has occurred among young men in military service in northern Thailand. The Thai AIDS prevention and control program might be implemented by other countries experiencing major epidemics of heterosexually transmitted HIV infections. Similar prevention programs targeted at other populations in Thailand and elsewhere in Asia are needed to decrease the spread of the HIV epidemic.

The association of herpes simplex virus type 2 (HSV-2), Haemophilus ducreyi, and syphilis with HIV infection in young men in northern Thailand.

To evaluate the association between sexually transmitted diseases that commonly may cause genital ulceration and prevalent and incident HIV infections, we conducted three case control studies in a cohort of 21-year-old male military conscripts in northern Thailand. The men were evaluated at baseline in 1991 and semiannually until their discharge 2 years later. Serologic evidence of infection with herpes simplex virus type 2 (HSV-2), Haemophilus ducreyi, and HIV were more frequent at baseline in 83 men with a history of genital ulcer than in 97 men without such a history. Seropositivity to H. ducreyi (odds ratio [OR] = 3.46), HSV-2 (OR = 3.83), and syphilis (OR = 1.53) were more common in HIV-positive than HIV-negative men. Men (N = 45) who seroconverted to HIV while in the military were more often seropositive for H. ducreyi and HSV-2 before HIV seroconversion and also were more likely to seroconvert to HSV-2 and H. ducreyi during the same interval as their HIV seroconversion compared with men who remained HIV-negative. These data suggest that HSV-2 and H. ducreyi may be both markers for high-risk sexual behavior and risk factors for HIV infection among young men in Thailand.

PIP: Three case-control studies conducted in 1991-93 in a cohort of 21-year-old male military conscripts in northern Thailand investigated the association between HIV infection and three sexually transmitted diseases (STDs) commonly associated with genital ulceration: herpes simplex virus type 2 (HSV-2), Haemophilus ducreyi, and Treponema pallidum. The studies compared 83 men with a history of genital ulcer disease (GUD) at baseline and 97 men without such a history, 103 men who were HIV-positive at baseline and 110 randomly selected HIV-negative conscripts, and 45 men who seroconverted to HIV while they were in the military and 124 men who remained HIV-negative throughout military service. The first study detected a significant dose-response association between number of commercial sex worker visits in the past year, lifetime number of sexual partners, and a history of GUD. Among men with GUD at baseline compared with those without GUD, the odds ratios were 2.52 for HSV-2, 2.02 for H. ducreyi, 0.97 for syphilis, and 2.14 for HIV. In the second study, HIV-infected men were significantly more likely than HIV-negative men to have antibodies to HSV-2 and H. ducreyi and a history of syphilis or gonorrhea. In the third study, men who converted to HIV were significantly more likely to have antibodies to H. ducreyi and HSV-2 at the visit before seroconversion than those who remained HIV-negative. Two independent predictors of seroconversion--HSV-2 seropositivity before conversion and 10 or more lifetime sexual partners--were identified. In northern Thailand, GUD, especially H. ducreyi and HSV-2, may be both a marker for increased HIV risk and a cofactor for HIV transmission.

Antigenic analysis of influenza viruses isolated in Thailand between 1991 and 1994.

We studied the epidemiology of influenza viruses in Thailand by isolating them and comparing their antigenic features with those of Japanese isolates. Between 1991 and 1994, 32 strains were isolated from 186 throat swab specimens. Twenty-one of the 32 isolates were of type A, subtype H3N2, and 11 strains were type B. It was suggested that the isolates of type A, subtype H3N2, drifted antigenically from A/Beijing/352/89-like to A/Kitakyusyu/159/93-like variants used as reference strains for comparison. The type B isolates in 1991 were suspected to be antigenically different from those of B/Bangkok/163/90, Thailand, in HI tests. These 1991 isolates were similar to B/Mie/1/93, which was isolated in the latter half of the epidemic in Japan in winter 1992/1993.

Human immunodeficiency virus infection and self-treatment for sexually transmitted diseases among northern Thai men.

BACKGROUND AND OBJECTIVES: Self-treatment for sexually transmitted diseases (STD) is common, but little studied, in Thailand, and its influence on human immunodeficiency virus (HIV) infection is unknown. GOALS: To assess STD self-treatment and self-prophylaxis behaviors as well as HIV risks and serostatus among northern Thai men. STUDY DESIGN: Cross-sectional report from a cohort of military conscripts (N = 869). HIV and STD seroprevalence and reported risk behaviors, including STD history and antibiotic self-treatment, were obtained. Associations between STDs and self-treatment or prophylaxis and HIV infection were analyzed using t-tests, odds ratios, and logistic regression. RESULTS: The prevalence rate for HIV was 12.3%, and for syphilis it was 2.2%. Men who were seropositive for HIV were more likely to report having sex with commercial sex workers (OR 9.1), to have had an STD (OR 5.96) and to report inconsistent condom use with commercial sex workers (OR 3.13). Of 282 men reporting any STD, 65.2% treated themselves with antibiotics, and 8.5% used them before commercial sex. Among those who frequented commercial sex workers, 98.7% took preventive steps after sex by increasing urine output (69.2%), washing the genital area (28.9%), and using antibiotics (0.9%). Men reporting STD self-treatment were less likely to be HIV infected (OR 0.53; 95% CI 0.31, 0.93). CONCLUSIONS: These men are attempting to prevent HIV and STDs. Self-treatment with antibiotics may lower HIV risks associated with bacterial STD in a high-prevalence population.

PIP: In May 1993, at 11 military camps in the upper northern region of Thailand, civilians interviewed 869 men aged 21-29 years (most of whom were 21 years old) so researchers could determine the frequency and variety of self-treatment and self-prophylaxis behaviors for sexually transmitted disease (STD) and the relationship of these behaviors with the prevalence of HIV infection. 12.3% of the men at conscription into the military tested positive for HIV infection. 32.5% had ever had an STD. The leading STDs and syndromes were gonorrhea (16.1%), penile discharge with pus (15.5%), and pain while urinating (11.4%). HIV-positive men were more likely to have had sex with commercial sex workers (CSWs) (odds ratio [OR] = 9.14), to have had an STD (OR = 5.96), and not to use condoms consistently when having sexual intercourse with CSWs (OR = 3.13). 65.2% of men who had ever had an STD self-treated with antibiotics. 8.5% of men who had ever had an STD used antibiotics, particularly chloramphenicol, before having intercourse with a CSW. Among all the men who had sexual intercourse with CSWs, almost all (98.7%) had adopted steps to prevent STDs: increasing urine output (69.2%), washing the genitals with soap and water (28.9%), and using antibiotics (0.9%). Men who self-treated with antibiotics after having intercourse with CSWs were less likely to have HIV infection (OR = 0.53). Antibiotic use before intercourse with CSWs did not have as strong a protective effect as it did after intercourse (OR = 0.74). The protective effect of self-treatment was significant, even when controlling for syphilis, gonorrhea, lymphadenopathy, penile discharge with pus, and condom use with a CSW. These findings show that some sexually active men in northern Thailand are trying to prevent HIV and other STDs and that self-treatment with antibiotics may reduce the HIV risk associated with bacterial STDs in a high prevalence population.

Epidemiologic risk factors for incident sexually transmitted diseases in young Thai men.

BACKGROUND AND OBJECTIVES: Prospective studies of incidental sexually transmitted diseases in developing countries rarely have been reported. As the human immunodeficiency virus epidemic widens, knowledge of the epidemiology of sexually transmitted diseases as co-factors for human immunodeficiency virus infection is viewed as vitally important. GOAL: To determine epidemiologic risk factors for incidental sexually transmitted diseases in young men in northern Thailand. STUDY DESIGN: A cohort of 2,417 men selected by lottery for military conscription was followed an average of 22 months, with epidemiologic risk factors and sexually transmitted disease histories assessed semiannually. Sexually transmitted diseases were determined by physician or symptom histories obtained by interview. RESULTS: Sexually transmitted disease incidence was 17.04 per 100 person-years. Gonorrhea and chancroid were commonly reported, whereas incident syphilis was rare. Sexually transmitted disease incidence declined significantly in the 2-year period. Most sexually transmitted diseases were acquired through commercial sex patronage. However, among men who did not report visiting a brothel, there was a significant increase in sexually transmitted diseases among men reporting sex with a girlfriend. Other risk factors included inconsistent condom use, drug use, and low educational level. Frequent alcohol use was associated with incident sexually transmitted diseases in bivariate analysis, but drinking at the time of last brothel visit was not associated with increased sexually transmitted diseases. CONCLUSIONS: Sexually transmitted disease control in Thailand is based on an integrated sexually transmitted disease clinic system. Many commercial sex workers are examined and treated routinely, but too infrequently to reduce sexually transmitted disease transmission between them and their male clients. Condom-use levels in commercial sex settings still may be too low to reduce sexually transmitted disease transmission. More consistent and effective sexually transmitted disease treatment of commercial sex workers and their clients and education of men on the effective and consistent use of condoms is required to reduce the risks of sexually transmitted disease transmission in this population.

PIP: A cohort of 2417 male military conscripts had their epidemiologic risk factors for exposure to sexual transmitted diseases (STD) and STD histories assessed semiannually for an average of 22 months. STDs were determined by physician or symptom histories obtained during interview. These measures were undertaken to determine the epidemiologic risk factors for incidental STDs in young men in northern Thailand. The incidence of STD was 17.04 per 100 person-years. Gonorrhea and chancroid were commonly reported, while it was rare to see syphilis. The incidence of STD declined significantly during the two-year period. Most STDs were acquired through having sex with prostitutes. However, among men who did not report visiting a brothel, there was a significant increase in STDs among men reporting having sex with their girlfriends. Other risk factors included inconsistent condom use, drug use, and low educational level. Frequent alcohol use was associated with incident STDs in bivariate analysis, but drinking at the time of last brothel visit was not associated with increased STDs.

Hepatitis B immunization: a potential incentive to HIV vaccine trial participation in Thailand?

To assess the effectiveness of hepatitis B immunization as an incentive to retention in HIV seroincidence studies and future HIV vaccine trials in northern Thailand, subjects enrolled in three HIV seroincidence cohorts were screened for hepatitis B markers and seronegatives were offered free hepatitis B immunization. Cohorts studied included female commercial sex workers (CSWs), male sexually transmitted disease (STD) patients, and recently discharged military conscripts. Subjects who agreed to the immunization program were compared with those not enrolled to determine the utility of immunization as an incentive to cohort retention. Full immunization was achieved for 273 (89.5%) of 305 vaccinees; only 323 (60.6%) of 533 subjects not immunized completed the same follow-up visits (OR = 1.49, 95% and CI = 1.27, 1.75). Hepatitis B vaccination was a significant incentive for completion of the follow-up program. The vaccination program had the greatest effect on the CSWs; a similar effect was seen for male STD patients, but not for discharged conscripts. Despite the immunization program, follow-up rates at 12 months were similar in the immunized and nonimmunized groups.

Risk factors for HIV-1 seroconversion among young men in northern Thailand.

OBJECTIVE: To identify behavioral and sociodemographic risk factors for incident human immunodeficiency virus-1 (HIV-1) infection among healthy young men in northern Thailand. DESIGN: Men inducted into military service in northern Thailand in May and November 1991 were followed at 6-month intervals until discharge 2 years later. Trained nonmilitary interviewers identified risk factors for HIV-1 infection through interviews with the men. SETTING: Thirteen military bases in northern Thailand. PARTICIPANTS: A total of 1932 seronegative men, aged 19 to 23 years (average age, 21 years) at enrollment, conscripted into the Royal Thai Army and Air Force from six upper-northern Thai provinces. MAIN OUTCOME MEASURES: Human immunodeficiency virus-1 seroincidence as determined through enzyme-linked immunosorbent assay and verified by Western blot, and univariate and multivariate analyses of risk factors related to HIV-1 incidence. RESULTS: A total of 85 men seroconverted to HIV-1 over the period of observation, giving an incidence rate of 2.43 per 100 person-years. Factors strongly associated with HIV-1 seroconversion were frequency of visits to female commercial sex workers (CSWs), sex with men, and incident sexually transmitted diseases (STDs). High frequency of condom use showed a significant (P < .001) protective effect for HIV-1 incidence among men with a history of recent sex with female CSWs in univariate analysis, but a multivariate model demonstrated no difference in HIV-1 seroconversion rates by consistency of condom use. Multivariate analysis incorporating condom use showed that having sex with men (adjusted relative risk [RR], 2.59; 95% confidence interval [CI], 1.08 to 6.25), having sex with CSWs (adjusted RR ranged from 2.54 [95% CI, 1.81 to 3.58] to 2.74 [95% CI, 1.56 to 4.81]), and incident STDs (adjusted RR, 2.38 [95%, CI, 1.31 to 4.32]) to be predictors of incident HIV-1 infection. Substance use was not associated with HIV-1 seroconversion rates in multivariate analysis. CONCLUSION: The HIV-1 incidence in this cohort of young men appears to be primarily attributable to having sex with female CSWs. Condom use provided some protection, although not in multivariate analysis; however, condom use has previously been shown likely to be useful in preventing HIV-1 transmission. Thus, programs to increase effective condom use in brothels are essential. Efforts to extend condom use to non-CSW partners are especially needed. More effective prevention and treatment of STDs may also be necessary to decrease HIV-1 infection in this population.

Dynamics of risk behavior for HIV infection among young Thai men.

The objective of this investigation was to analyze the dynamics of risk for HIV-1 infection among young men in Thailand. We conducted a prospective study in a cohort (n = 1,236) of young men, aged 19-23 years at conscription into the Royal Thai Army and Air Force from six provinces in northern Thailand in May 1991 who were followed until their discharge in April 1993. The outcome measure was change since conscription in the frequency of self-reported sex with female commercial sex workers (CSW) during military service. Although 42% of conscripts reported no visit to a female CSW in the year prior to conscription, most had a visit during military service. Men who visited female CSWs infrequently at baseline increased their visits somewhat over time, whereas those with high initial rates of CSW visits decreased. Based on an assumed stable distribution over time, change from baseline was not statistically significant. Only marital status and high baseline CSW visit rates were associated with diminished visit frequency in multivariate analysis. No differences were seen in patterns of change in CSW visits by HIV-1 serostatus. More aggressive preventive interventions are needed to reduce the frequency of CSW visits in northern Thailand, a setting where 40-80% of all female CSWs working in brothels are now HIV seropositive.

Willingness to participate in AIDS vaccine trials among high-risk populations in northern Thailand.

OBJECTIVES: To determine the anticipated participation in a prophylactic AIDS vaccine trial and to identify perceived benefits and barriers to enrollment of HIV-seronegative volunteers at risk of HIV infection in northern Thailand. DESIGN: A cross-sectional survey. METHODS: Subjects interviewed in a cross-sectional survey included female commercial sex workers (n = 215), men attending sexually transmitted disease clinics (n = 219), conscripts in the Royal Thai Army (n = 1453), and men discharged from the army (n = 293) who had returned to civilian life. We determined AIDS vaccine knowledge and attitudes, perceived vulnerability to HIV infection, barriers and incentives to participate in a future vaccine trial and agreement to participate in a randomized trial. RESULTS: Awareness of vaccines (88-97%) and AIDS vaccine development efforts (62-77%) were common and viewed to be a complement to behavior change (74-94%). Approximately 25% of subjects would definitely join a trial if asked, and an additional 38% would accept an AIDS vaccine if they were convinced it would be safe and effective. Important barriers to participation included concerns with discrimination (16-45%), short- (37-60%) and long-term (30-55%) vaccine side-effects, fear of disability and death (36-58%), and beliefs that partners would refuse to have sex (24-49%) after immunization. The principal inducement to join a trial was health insurance (62%). CONCLUSION: Potential HIV vaccine trial participants have several fears of joining a vaccine study at this time. Information derived from Phase I/II trials is needed to address these concerns if enrollment in efficacy trials is to be successful in the near future.

PIP: Thailand has been designated a site for preventive human immunodeficiency virus (HIV) vaccine trials, and Phase I and II trials are currently underway. To assess the feasibility of large-scale Phase III trials involving high-risk individuals, questionnaires were administered to four cohorts of potential participants from North Thailand: 215 female commercial sex workers recruited from sexually transmitted disease (STD) clinics, 219 male STD clients from the same area, 1453 men conscripted into the Royal Thai Army in 1993, and 293 men discharged from the Army in 1993. Approximately 25% of members of each cohort indicated they would definitely join a prophylactic acquired immunodeficiency syndrome (AIDS) trial. The major barriers to participation were concerns about vaccine safety (61% of military cohorts and 32% of civilians) and fear of acquiring AIDS through vaccination (21%). Also expressed were concerns about social discrimination, immediate side effects, and rejection by sexual partner. Two-thirds of respondents indicated that provision of a five-year family health insurance plan would induce them to participate in a vaccine trial, while another 25% did not require any incentive. Overall, these findings indicate that steps must be taken to alleviate fears and misconceptions associated with HIV vaccines before Phase III is initiated.

Same-sex behavior, sexually transmitted diseases and HIV risks among young northern Thai men.

OBJECTIVES: To assess the risks for HIV infection and sexually transmitted diseases (STD) among young northern Thai men who have sex with men (MSM), and to examine the possible role of male same-sex behavior in the northern Thai HIV/AIDS epidemic. METHODS: Two cohorts of northern Thai military conscripts and one cohort of recently discharged conscripts, a total of 2047 men, were studied. Data were collected by interview on behavioral risk factors, and sera were examined for syphilis and HIV-1 antibodies. Univariate and multiple logistic regression analyses were used to determine risk factors associated with HIV and STD, and to assess the frequency and patterns of same-sex behaviors among these men. RESULTS: Of 2047 men, 134 (6.5%) reported one or more male lifetime sex partners. Of these MSM, 130 (97.0%) also had female partners, and four (3.0%) had exclusively male partners. Compared with men who reported only female sex partners, MSM had a higher number of lifetime sex partners, a higher mean number of female sex partners, more female and male commercial sex worker (CSW) partners, and were more likely to be married. MSM were significantly more likely than exclusively heterosexual men to report having had any STD [odds ratio (OR), 2.72], gonorrhea (OR, 2.05), syphilis (OR, 3.17), non-gonococcal urethritis (OR, 4.54) and penile discharges (OR, 6.24). They were at borderline increased risk for HIV infection [OR, 1.51; 95% confidence interval (CI), 0.95-2.41]. Men with more than one lifetime male sex partner compared with those with only one partner were significantly more likely to be HIV-infected (OR, 2.81; 95% CI, 1.09-7.19). CONCLUSIONS: Northern Thai MSM are a high-risk population for STD, including HIV. Reported same-sex behavior in this population appears to vary considerably with data collection techniques. HIV and STD prevention strategies aimed at changing unsafe sexual practices may need to be targeted to the general population of young Thai men.

PIP: In northern Thailand, baseline interviews with and blood testing for syphilis and HIV-1 antibodies of military conscripts were conducted during May-November 1993. Researchers also examined conscripts discharged in April 1993. They interviewed and tested a total of 2047 men. 134 men (6.5%) had had at least one male sex partner. (These men are referred to as MSM.) Only 4 (2.9%) had had sex with only men. The remaining 130 (97.1%) had also had female sex partners. The 134 MSM men were more likely than heterosexual men to be married (odds ratio [OR] = 2.67) and to have a girlfriend with whom they had sex (OR = 1.6). They were also more likely than heterosexual men to have ever had any sexually transmitted disease (STD) (OR = 2.71), gonorrhea (2.05), syphilis (OR = 3.17), nongonococcal urethritis (OR = 4.54), penile discharge with pus (OR = 2.47), watery penile discharge (OR = 6.24), and dysuria (OR = 2.43). The overall HIV prevalence was 12.1% (247 men). MSM men were only somewhat more likely to be HIV infected (PR = 1.51). MSM men with more than one male lifetime partner were significantly more likely to be infected with HIV than those with only one male partner (OR = 2.89). Same-sex behavior was more common among discharged men who had returned to civilian life than those were still in the military (9.3% vs. 6.5%). Discharged bi/homosexual men was the only group of Royal Thai Army current or former conscripts in which sex with men was independently associated with HIV infection (27.3% vs. 12.4% for HIV-infected heterosexual former conscripts; OR = 2.54). Among all subjects, HIV infection was associated with ever visited a female commercial sex worker (OR = 4.16) and ever had any STD (OR = 5.47), gonorrhea (OR = 3.08), syphilis (OR = 3.81), genital herpes (OR = 3.54), genital warts (OR = 3.56), and genital ulcer disease (OR = 5.59). These findings show that MSM in Northern Thailand are at high risk of STDs and HIV. HIV/STD prevention efforts should target all young Thai men and try to change high risk sexual practices.

Preparatory studies for possible HIV vaccine trials in northern Thailand.

We studied several populations of human immunodeficiency virus (HIV)-seronegative individuals from northern Thailand who were believed to be at relatively high risk of HIV infection in order to assess their potential suitability for inclusion in a preventive HIV vaccine trial. Included were female commercial sex workers (CSWs), male sexually transmitted disease (STD) clinic patients, male conscripts into the Royal Thai Army (RTA), and men who were recently discharged from the army. We evaluated their HIV prevalence, their interest in study participation, their compliance with prospective follow-up, and their HIV incidence. Among 1068 female CSWs the baseline HIV prevalence was 38.3%; of 659 HIV seronegatives 395 (59.9%) agreed to enrollment in the study. Follow-up at 6-9 months was 73.2%; it was 58% in brothel-based CSWs and 85% in non-brothel-based CSWs. Overall HIV incidence in CSWs was 8.2 per 100 person-years; incidence was 29 per 100 person-years in brothel-based CSWs and 4 per 100 person-years in non-brothel-based CSWs. Among 1031 male STD clinic patients, baseline HIV prevalence was 15.9%, follow-up was successful in 98.1%, and HIV incidence was 4.0 per 100 person-years. Among four cohorts of RTA conscripts who entered the military in 1991 and 1993, baseline HIV prevalence has been about 12%, follow-up about 90%, and HIV incidence has varied from 1.2-3.2 per 100 person-years. Discharged RTA conscripts have had baseline HIV prevalence of about 13%, successful follow-up of 94%, and an HIV incidence of about 5 per 100 person-years.(ABSTRACT TRUNCATED AT 250 WORDS)

Behavioral and sociodemographic risks for frequent visits to commercial sex workers among northern Thai men.

OBJECTIVE: The transmission of HIV-1 in Thailand has recently been attributed to exposure to infected commercial sex workers (CSW). We sought to identify risk factors for patterns of CSW visits among northern Thai men. DESIGN: Retrospective recall of lifetime and recent CSW visits and associated risk factors were obtained by interview. SETTING: Two military bases in northern Thailand. PARTICIPANTS: We enrolled two cohorts (n = 2417) of young men, aged 19-23 years, who were conscripted into the Royal Thai Army and Air Force from six provinces in northern Thailand in May and November 1991. MAIN OUTCOME MEASURES: Frequency of self-reported lifetime and recent sex with CSW. RESULTS: Multivariate results showed that lower socioeconomic status, early first intercourse and substance-use factors (alcohol, marijuana, other drugs, and smoking) associated with lifetime and recent sex with CSW. Sexual intercourse with other female partners, lower price paid at last CSW visit and frequency of condom use with CSW did not differentiate frequent from infrequent CSW visitors. CONCLUSIONS: Limits in the frequency of sex with CSW, improved condom practices and reduction of drinking prior to CSW visits would all appear to provide substantial protection from exposure to HIV-1 in this setting.

PIP: At least 400,000 Thais are believed to be infected with HIV-1 and the principal route of infection is heterosexual intercourse. Given that the transmission of HIV in Thailand has recently been attributed to contact with infected prostitutes, the authors set out to identify the risk factors for patterns of prostitute visits among northern Thai men. 2417 male conscripts to the Royal Thai Army and Air Force aged 19-23 years who enrolled in 2 military bases in northern Thailand in May and November 1991 were recruited for the study. In interviews, 454 reported never having visited a prostitute, 1385 reported at least 1 episode of sexual activity with a prostitute in the preceding year, and 578 reported having had sex with a prostitute in the past. The multivariate analysis found lower socioeconomic status, early first intercourse, and the use of alcohol, marijuana, smoking, and other drugs to be associated with lifetime and recent sex with prostitutes. Sexual intercourse with female partners, lower price paid at last prostitute visit, and frequency of condom use with prostitutes, however, did not differentiate frequent from infrequent prostitute visitors. With the goal of reducing the degree of HIV transmission among these young men, steps should be made to encourage a reduction in the frequency of sex had with prostitutes, to improve condom use, and to reduce drinking before visiting prostitutes.

Risk factors for HIV infection among young adult men in northern Thailand.

OBJECTIVE: To determine the sociodemographic and behavioral risk factors associated with human immunodeficiency virus (HIV) infection in two cohorts of young men selected for military service in northern Thailand. DESIGN: Military conscripts were studied cross-sectionally after conscription in May 1991 and November 1991. Risk factors were assessed by interview with trained nonmilitary interviewers. SETTING: Two military training bases in Chiang Mai, Thailand. PARTICIPANTS: A total of 2417 young men aged 19 to 23 years (mean age, 21 years) conscripted by lottery into military service in the Royal Thai Army or Royal Thai Air Force from six provinces in northern Thailand. MAIN OUTCOME MEASURES: Human immunodeficiency virus seroprevalence by enzyme-linked immunosorbent assay confirmed by Western blot and univariate and multivariate analyses of sociodemographic and behavioral risk factors associated with HIV seroprevalence. RESULTS: Overall, 289 (12.0%) of 2417 men were HIV-seropositive at baseline. The strongest associations with being HIV positive were heterosexual activities. History of sex with a female commercial sex worker (CSW) was frequent (96.5% of men who were HIV-positive and 79.0% of men who were HIV-negative) and strongly associated with HIV infection on univariate and multivariate analyses (adjusted odds ratio, 1.60 to 2.07, depending on the frequency of CSW contact). Also, sexually transmitted diseases were common and associated with HIV infection in both univariate and multivariate analyses (adjusted odds ratio, 3.36). Sex with other males and injection drug use were uncommon and not associated with HIV infection. Condom use was reported in 61.5% of men at last sex with a CSW but was not shown to be protective of prevalent HIV infection. CONCLUSION: The epidemic of HIV infection has spread widely among young men in northern Thailand, despite reported frequent and recent use of condoms during sex with female CSWs. Control of HIV infection in this population will probably require more regular and effective use of condoms, prevention and treatment of sexually transmitted diseases, and reduction in the frequency of CSW contact.