Declining prevalence of HIV-1 infection in young Thai men

The US Military Commitment to Vaccine Development: A Century of Successes and Challenges

The US military has been a leading proponent of vaccine development since its founding. General George Washington ordered the entire American army to be variolated against smallpox after recognizing the serious threat that it posed to military operations. He did this on the recommendation from Dr. John Morgan, the physician-in-chief of the American army, who wrote a treatise on variolation in 1776. Although cases of smallpox still occurred, they were far fewer than expected, and it is believed that the vaccination program contributed to victory in the War of Independence. Effective military force requires personnel who are healthy and combat ready for worldwide deployment. Given the geography of US military operations, military personnel should also be protected against diseases that are endemic in potential areas of conflict. For this reason, and unknown to many, the US military has strongly supported vaccine research and development. Four categories of communicable infectious diseases threaten military personnel: (1) diseases that spread easily in densely populated areas (respiratory and dysenteric diseases); (2) vector-borne diseases (disease carried by mosquitoes and other insects); (3) sexually transmitted diseases (hepatitis, HIV, and gonorrhea); and (4) diseases associated with biological warfare. For each category, the US military has supported research that has provided the basis for many of the vaccines available today. Although preventive measures and the development of drugs have provided some relief from the burden of malaria, dengue, and HIV, the US military continues to fund research and development of prophylactic vaccines that will contribute to force health protection and global health. In the past few years, newly recognized infections with Zika, severe acute respiratory syndrome, Middle East respiratory syndrome viruses have pushed the US military to fund research and fast track clinical trials to quickly and effectively develop vaccines for emerging diseases. With US military personnel present in every region of the globe, one of the most cost-effective ways to maintain military effectiveness is to develop vaccines against prioritized threats to military members' health.

Stigmatizing attitudes toward people living with HIV among general adult Thai population: Results from the 5th Thai National Health Examination Survey (NHES)

Background

HIV-related stigma and discrimination is a significant driver of the HIV and AIDS epidemic. UNAIDS encourages all nations to monitor progress toward elimination of this problem. This study measured the level of stigmatizing attitudes toward people living with HIV (PLHIV) among Thai adults in the general population using recommended global tools.

Methods

Data from the 5th National Health Examination Survey, conducted in 2014 were used. The survey utilized six questions recommended by the Global Stigma and Discrimination Indicator Working Group and was administered to participants aged 20–59 years old. All analyses were weighted to take into account of the probability of sampling the same-age Thai population. Factors related to a discriminatory attitude according to UNAIDS, defined as agreed to at least one of the two discriminatory issues, were evaluated using Chi square tested and multivariable logistic regression.

Results

Of the 10,522 respondents, the most prevalent stigmatizing attitude was anticipated stigma (76.9%), followed by perceived stigma (69.2%), fear of HIV infection (57.0%), and social judgment (38.2%). Fifty-eight point six percent had discriminatory attitudes according to the UNAIDS global indicator. Independent predictors were being female (AOR = 1.21: 95% CI 1.14–1.29), aged 20–39 (AOR = 1.19: 95% CI 1.09–1.30) or 50–59 (AOR = 1.18: 95%CI 1.12–1.26), being Muslim (AOR = 2.03: 95%CI 1.55–2.66), earning < 10,000 Baht/month (AOR = 0.93: 95%CI 0.88–0.99), and living in the Northeast (AOR = 1.67: 95%CI 1.39–2.00) or in Bangkok (AOR = 1.73: 95%CI 1.45–2.07).

Conclusions

More than half of the general adult Thai population had stigmatizing attitudes toward PLHIV. The study provided valuable baseline information which could be used as comparison for follow-up surveys with other countries. Interventions to improve Thai society’s knowledge and attitudes toward HIV/AIDS are urgently needed.

Moral Panic and the Construction of National Order

This article examines some of the major concepts used to model the Thai AIDS epidemic and to direct interventions, in particular, the concepts of discrete risk groups and of the sequential spread of HIV from group to group in a wave-like fashion which, although they have been largely discredited in the international AIDS literature, retain a high degree of currency in Thailand. I argue that Thailand’s HIV/AIDS epidemic had the effect of bringing sexual practices from the private sphere into the public arena, where the concept of risk group rendered visible the social body of modern Thailand as a hierarchy of risk, with specific groups attributed behaviours necessitating control. This notion found enduring favour in Thailand because it reinforced existing social prejudices about members of groups such as the male underclass, prostitutes and injecting drug users, and legitimated the claims of government and non-government organizations for the monitoring and control of these groups. There has been a high level of consensus over this strategy, and a lack of competing discourses. Thus Thai AIDS discourse has not only failed to transcend state and middle-class notions of morality and normativity, but it has also failed to come to terms with Thailand’s changing sexual cultures.

Risk Factors for HIV Infection among Young Thai Men during 2005-2009

Background

Thailand is one of several countries with a continuing generalized HIV epidemic. We evaluated the risk factors for HIV prevalence among 17–29 year old men conscripted by a random process into the Royal Thai Army (RTA) in 8 cohorts from 2005–2009.

Methods

A series of case-cohort studies were conducted among the male RTA conscripts who had been tested for HIV seroprevalence after they were inducted. Men who were HIV positive were compared with a systematic random sample (1 in 30–40) of men from the total population of new conscripts. Each subject completed a detailed risk factor questionnaire.

Results

A total of 240,039 young Thai men were conscripted into the RTA and were screened for HIV seroprevalence between November 2005 and May 2009. Of 1,208 (0.5%) HIV positive cases, 584 (48.3%) men were enrolled into the study. There were 7,396 men who were enrolled as a comparison group. Among conscripts who had an education lower than a college-level, the independent risk factors for HIV infection were age in years (AOR 1.38, 95% CI 1.28–1.48), a history of sex with another man (AOR 3.73, 95% CI 2.70–5.13), HCV infection (AOR 3.89, 95% CI 2.56–5.90), and a history of sex with a female sex worker (FSW) (AOR 1.35, 95% CI 1.10–1.66). Among conscripts who had a college degree, the independent risk factor for HIV infection was a history of sex with another man (AOR 23.04, 95% CI 10.23–51.90). Numbers of sexual partners increased and the age at first sex, as well as the use of condoms for sex with a FSW decreased in successive cohorts.

Conclusion

The HIV seroprevalence among cohorts of 17–29 years old men has remained at about 0.5% overall during 2005–2009. The most significant behavior associated with HIV prevalence was a history of sex with another man. Our data indicate continuing acquisition of HIV among young men in Thailand in recent years, especially among men with a history of same sex behavior.

Behaviour and communication change in reducing HIV: is Uganda unique?

The clearest example of declines in HIV prevalence and changes in sexual behaviour comes from Uganda. Are there lessons to learn for other countries or is Uganda unique? In this paper, we assess the epidemiological and behavioural data on Uganda comparatively to other African countries and then analyse data from other populations where HIV has declined. In Uganda, HIV prevalence declined from 21% to 9.8% from 1991-1998, there was a reduction in non-regular sexual partners by 65% and greater levels of communication about AIDS and people with AIDS through social networks, unlike the comparison countries. There is evidence of a basic population level response initiated at community level, to avoid risk, reduce risk behaviours and care for people with AIDS. The basic elements-a continuum of communication, behaviour change and care-were integrated at community level. They were also strongly supported by distinctive Ugandan policies from the 1980s. We identify a similar, early behaviour and communication response in other situations where HIV has declined: Thailand, Zambia and the US Gay community. In Thailand, visits to sex workers decreased by 55% and non-regular partners declined from 28% to 15% (1990-1993): as important as the '100% condom use policy'. Similarly, in Zambia and Ethiopia risk behaviour has decreased and analysis of Sexually Transmitted Disease (STD) rates among Gay populations in the USA shows a decline from as early as 1985 in White Gay populations, with later declines in Hispanic and Black Gay populations. These responses preceded and exceeded HIV prevention. However, where they were built on by distinctive HIV policies, HIV prevention has been scaled and led to national level declines in HIV. It is not easy to transfer the lessons of these successes. They require real social and political capital in addition to financial capital. Nevertheless, similar characteristics are present in community responses in Africa, Asia and USA, and even in fragmented signs of HIV declines in other African cities. Only in a few situations has this behaviour and communication process been recognised, mobilised and built on by HIV prevention policy. Where this has occurred, HIV prevention success has been greater than biomedical approaches or methods introduced from outside. It represents a social vaccine for HIV from Africa, and is available now.

Biomedical HIV prevention research and epidemic control in Thailand: two sides of the same coin

For a country with a moderate adult HIV prevalence of just over 1% in 2012, Thailand is widely perceived as having made some extraordinary contributions to the global management of the HIV/AIDS pandemic. It has been promoted as a model of effective HIV control and applauded for its leadership in providing access to antiretroviral treatment. Thailand has also received international recognition for its contribution to biomedical HIV prevention research, which is generally perceived as exceptional. In this paper, Thailand's global role model function as an example of effective HIV/AIDS control and high-quality biomedical HIV prevention research is re-evaluated against the background of currently available data and more recent insights. The results indicate that Thailand's initial response in raising the level of the political significance of HIV/AIDS was indeed extraordinary, which probably prevented a much larger epidemic from occurring. However, this response transpired in unusual extraconstitutional circumstances and its effectiveness declined once the country returned to political normalcy. Available data confirm the country's more than exceptional contribution to biomedical HIV prevention research. Thailand has made a huge contribution to the global management and control of the HIV/AIDS pandemic.

The importance of militaries from developing countries in global infectious disease surveillance

Military forces from developing countries have become increasingly important as facilitators of their government's foreign policy, taking part in peacekeeping operations, military exercises and humanitarian relief missions. Deployment of these forces presents both challenges and opportunities for infectious disease surveillance and control. Troop movements may cause or extend epidemics by introducing novel agents to susceptible populations. Conversely, military units with disease surveillance and response capabilities can extend those capabilities to civilian populations not served by civilian public health programmes, such as those in remote or post-disaster settings. In Peru and Thailand, military health organizations in partnership with the military of the United States use their laboratory, epidemiological, communications and logistical resources to support civilian ministry of health efforts. As their role in international affairs expands, surveillance capabilities of militaries from developing countries should be enhanced, perhaps through partnerships with militaries from high-income countries. Military-to-military and military-to-civilian partnerships, with the support of national and international civilian health organizations, could also greatly strengthen global infectious disease surveillance, particularly in remote and post-disaster areas where military forces are present.

How Uganda reversed its HIV epidemic

Uganda is one of only two countries in the world that has successfully reversed the course of its HIV epidemic. There remains much controversy about how Uganda's HIV prevalence declined in the 1990s. This article describes the prevention programs and activities that were implemented in Uganda during critical years in its HIV epidemic, 1987 to 1994. Multiple resources were aggregated to fuel HV prevention campaigns at multiple levels to a far greater degree than in neighboring countries. We conclude that the reversed direction of the HIV epidemic in Uganda was the direct result of these interventions and that other countries in the developing world could similarly prevent or reverse the escalation of HIV epidemics with greater availability of HIV prevention resources, and well designed programs that take efforts to a critical breadth and depth of effort.

Temporal trends of HIV-related risk behavior among Brazilian military conscripts, 1997-2002

PURPOSE

To present selected results of military conscript surveys related to HIV/AIDS, conducted in Brazil, 1997-2002.

METHODS

Questionnaires including information on socio-demographic data, sexual behavior practices, sexually transmitted infections-related problems, and use of injecting drugs were completed by 30970 individuals, obtained through a 2-stage sampling. An index of sexual risk behavior was developed to take into account multiplicity of partners and irregularity of condom use. The HIV infection prevalence rate was estimated for 2002. Logistic regression was used to identify the most important determinants of HIV infection.

RESULTS

The percentage of regular condom use increased from 38% (1997) to 49% (2002), and the index of sexual risk behavior decreased from 0.98 in 1997 to 0.87, in 2002. The HIV infection prevalence rate was 0.09%, in 2002, which remained unchanged since 1998 Riskier sexual practices among young men with incomplete education and among "men who have sex with men" were found as well as among the participants who reported at least one sexually transmitted infections - related problem. The most important predictor of HIV infection was to be positive for syphilis.

CONCLUSIONS

The estimated value of the HIV infection prevalence supports the diagnosis of a concentrated HIV epidemic, in Brazil. Results indicate that particular attention needs to be paid for regional differentials, and for special subgroups, in Brazil.

Temporal trends in the prevalence of HIV and other transfusion-transmissible infections among blood donors in northern Thailand, 1990 through 2001

BACKGROUND

Thailand's epidemic of HIV infection, which began in 1988, has primarily involved heterosexual transmission of the virus. This study describes changes in prevalence of HIV and other infectious diseases among blood donors in northern Thailand from 1990 through 2001.

STUDY DESIGN AND METHODS

Serologic screening results and demographic data were analyzed from 276,066 donors screened at two blood collection facilities in Chiang Mai, Thailand, from 1990 through 2001.

RESULTS

The HIV prevalence peaked in 1991 to 1993 at 4.04 percent and then declined to 0.38 percent in 2001. The overall prevalence of HIV infection was 2.16 percent; HIV prevalence was higher among male (2.24%) than among female (0.64%) donors, in first-time donors, and in replacement volunteer donors. The majority of the donors were men and first-time donors throughout this study. The prevalence of antibodies to syphilis decreased significantly in both men and women. However, the prevalence of antibodies to HCV and HBsAg were stable.

CONCLUSIONS

The declining HIV prevalence from 1990 through 2001 among blood donors in two large blood banks in northern Thailand indicates significant progress toward recruitment of a safer donor population in a developing country despite a major HIV and AIDS epidemic involving the general population.

Environmental-structural factors significantly associated with consistent condom use among female sex workers in the Dominican Republic

OBJECTIVE

To examine the influence of environmental-structural factors in promoting consistent condom use (CCU) among female sex workers (FSW) and their regular paying partners in the Dominican Republic.

METHODS

A cross-sectional survey was conducted with 288 FSW recruited from 41 sex establishments in Santo Domingo from March to June 1998. Sex workers were asked about their sexual behavior, self-efficacy at negotiating safe sex, perceived intimacy with their most recent regular paying partner, and the physical, social and policy environment of the establishment where they worked. Factor and reliability analysis were utilized to develop aggregate measures for self-efficacy (Cronbach's Alpha 0.60), intimacy (Cronbach's Alpha 0.80), and environmental-structural support (Cronbach's Alpha 0.72).

RESULTS

Controlling for sociodemographic characteristics of participants in multivariate analyses, environmental-structural support for condom use and HIV/sexually transmitted infection (STI) prevention was a significant predictor of CCU (OR 2.16; CI 1.18-3.97) among FSW and their regular paying partners. Safe sex self-efficacy (OR 2.80; CI 1.31-5.97) and low perceived intimacy with the most recent regular paying partner (OR 7.20; CI 3.49-14.83) were also significantly associated with CCU in multivariate analysis.

CONCLUSION

Environmental-structural support for condom use and HIV/STI prevention is a significant predictor of CCU among FSW in the context of regular paying partnerships. Environmental-structural factors, in addition to relational and individual cognitive factors, should be assessed and addressed by behaviorally guided theory, research and interventions related to HIV/STI prevention and female sex work.

The evolving epidemiology of HIV infection and tuberculosis in northern Thailand

OBJECTIVES

To examine the association between HIV infection and tuberculosis (TB) and the proportion of TB attributable to HIV in Chiang Rai province, northern Thailand, in response to a rapidly changing incidence of HIV infection.

METHODS

Case-control study covering the period 1990 to 1998. Cases were all new TB patients seen at Chiang Rai Hospital. Controls were antenatal clinic attendees, delivery patients, surgical patients, blood donors, and military conscripts. Odds ratios (ORs) were calculated by year, age group, and sex, using each control group separately. The population attributable fraction was calculated by year.

RESULTS

During the study period, the number of new TB cases in Chiang Rai Hospital increased more than threefold. The ORs increased over time compared with all control groups for both sexes but did not vary consistently with age. The proportion of TB cases attributable to HIV rose to 72.0% in male patients and 65.8% in female patients by 1998.

CONCLUSIONS

The HIV epidemic has a profound and prolonged impact on TB burden. Despite the marked reduction in HIV incidence already seen in Chiang Rai, the HIV prevalence among TB cases and the proportion of cases attributable to HIV continue to rise.

Educational attainment and HIV-1 infection in developing countries: a systematic review

OBJECTIVES

To assess whether educational status is associated with HIV-1 infection in developing countries by conducting a systematic review of published literature.

METHODS

Articles were identified through electronic databases and hand searching key journals. Studies containing appropriately analysed individual level data on the association between educational attainment and HIV-1 status in general population groups were included.

RESULTS

Twenty-seven articles with appropriately analysed results from general population groups in developing countries were identified, providing information on only six countries. Large studies in four areas in Africa showed an increased risk of HIV-1 infection among the more educated, whilst among 21-year-old Thai army conscripts, longer duration of schooling was strongly protective against HIV infection. The association between education and schooling in Africa was stronger in rural areas and in older cohorts, but was similar in men and women. Serial prevalence studies showed little change in the association between schooling and HIV over time in Tanzania, but greater decreases in HIV prevalence among the more educated in Uganda, Zambia and Thailand.

CONCLUSIONS

In Africa, higher educational attainment is often associated with a greater risk of HIV infection. However, the pattern of new HIV infections may be changing towards a greater burden among less educated groups. In Thailand those with more schooling remain at lower risk of HIV infection.

Genetic analysis of incident HIV-1 strains among injection drug users in Bangkok: evidence for multiple transmission clusters during a period of high incidence

During 1995-1996, 1,209 HIV-1-negative injection drug users (IDUs) attending methadone treatment clinics operated by the Bangkok Metropolitan Administration in Bangkok, Thailand, were enrolled in a prospective cohort study. Through 1998, 133 of these IDUs had seroconverted to HIV-1; 130 of these seroconverters were included in this study. HIV-1 CRF01_AE and subtype B strains accounted for 79% and 21% of the incident infections, respectively. To examine phylogenetic relationships among these incident HIV-1 strains, we used several phylogenetic inference methodologies to analyze the env (C2-V4) sequences in blood samples collected soon after seroconversion. These analyses consistently revealed eight phylogenetic clusters comprising 21 incident strains (bootstrap method, >80%; six CRF01_AE and two subtype B clusters). Two factors were found to be associated with the eight clusters. The first factor was temporal: seven of the eight clusters comprised 17 sequences from IDUs whose estimated dates of seroconversion were within a period of high incidence from July 1996 through January 1997. The second factor was a possible geographic association: four clusters were observed among IDUs who had attended the same methadone treatment clinics. These phylogenetic clusters likely represent subgroups within larger HIV transmission networks among IDUs in Bangkok. Despite prevention efforts, the incidence of HIV-1 infection among the Bangkok IDU population continues to be high. A better understanding of transmission networks and factors associated with such networks can help guide prevention efforts.

HIV-1 in ethnic Shan migrant workers in northern Thailand

Northern Thailand has one of the highest rates of HIV-1 infection in Southeast Asia. It is also home to a large number of Burmese migrants, believed to be at high risk of HIV. Our 1999 survey of 429 Burmese migrant workers of Shan ethnic origin in Chiang Mai province found a 4.9% rate of HIV-1 prevalence (5.7% men, 3.8% women). This figure is almost double that of comparable population groups in Chiang Mai, e.g. pregnant women and military recruits. HIV prevention programmes are urgently needed for this vulnerable population.

HIV infection in young men in northern Thailand, 1991-1998: increasing role of injection drug use

Epidemic HIV-1 infections were first recognized in Thailand in 1988 but increased dramatically in the 1990s primarily as a result of sexual transmission. The Ministry of Public Health instituted programs, including condom promotion during commercial sex, and health education to prevent HIV transmission. We assessed the HIV infection prevalence and risk behaviors among eight cohorts of 21-year-old randomly selected male military conscripts in northern Thailand between 1991 and 1998 to evaluate temporal trends in HIV infection and risk behavior. The prevalence of HIV was 11.4% to 11.9% in 1991 through 1993 and progressively fell to 2.4% in 1998. The men reported progressive decreases in commercial sex from 80% in 1991 to 38% in 1998, increases in condom use for commercial sex to greater than 95% in 1998, and decreases in lifetime history of a sexually transmitted infection from 42% in 1991 to 4.4% in 1997. There was an increasing proportion of men who reported a history of injecting illicit drugs, however, which involved 1.0% of the men in 1991 but 4.2% in 1997. The population attributable risk of drug use for HIV infection increased in recent years; the proportion of HIV-positive men with a history of drug use increased from 1.0% in 1991 to 25.8% in 1998. The public health program to prevent the sexual transmission of HIV in Thailand continues to be highly successful. Nevertheless, injection drug use has emerged as an important risk behavior and is maintaining endemic HIV transmission in Thailand.

Continued high HIV-1 incidence in a vaccine trial preparatory cohort of injection drug users in Bangkok, Thailand

BACKGROUND

A large epidemic of HIV-1 subtype B began among injection drug users (IDUs) in Bangkok in 1988. Despite ongoing prevention efforts, HIV-1 prevalence among IDUs remained at 30-50% through the 1990s.

OBJECTIVES

To measure the incidence of HIV-1 infection and related risk factors to guide prevention efforts and to evaluate the feasibility of conducting an HIV vaccine efficacy trial.

DESIGN AND METHODS

A prospective cohort study in which IDUs attending methadone treatment programs in Bangkok were screened during 1995-1996 for enrollment into the study. IDUs found to be HIV-seronegative on two occasions were offered enrollment with follow-up visits every 4 months. On each visit participants were evaluated with a questionnaire and serologic testing.

RESULTS

A total of 1209 HIV-negative IDUs were enrolled. Through the end of 1998, the overall HIV-1 incidence rate was 5.8 (95% confidence interval, 4.8-6.8) per 100 person-years of follow-up. HIV-1 subtypes E and B accounted for 79 and 21% of infections, respectively. On multivariate analysis, HIV-1 seroconversion was primarily associated with the frequency of heroin injection, the sharing of injection equipment, and incarceration, especially with drug injection. Sexual behavior was not associated with increased risk for HIV-1. Risk factors for infection with HIV-1 subtypes E and B were similar.

CONCLUSION

HIV-1 transmission risk remains high among Bangkok IDUs despite methadone treatment and other current prevention strategies. There is an urgent need to address this ongoing epidemic, especially in jails and prisons. This study led to the initiation in 1999 of a phase III HIV-1 vaccine efficacy trial in this population.

HIV type 1 subtype E-infected patients with broadened, dual (B/E) V3 loop serology have increased cross-neutralizing antibodies

The two prevalent subtypes of HIV-1 circulating in Thailand are subtypes E and B. While the most prevalent subtype continues to be E using molecular typing assays, immunologically, a subset of subtype E-infected patients (3.4% in 1997) have binding antibodies to both the E and B V3 loops in a peptide ELISA. To assess the potential function of this dual (B/E) V3 reactivity, plasmas from patients with genetically defined HIV-1 subtype E infection and either E or B/E V3 serotypes were compared for magnitude and breadth of neutralization of seven primary and laboratory-adapted subtype B and E viruses. Dually reactive (B/E) plasmas showed significantly increased cross-neutralizing activity against subtype B viruses (p < 0.001), and increased neutralization of the panel of viruses overall (p < 0.02), as compared to monoreactive E serotype plasmas. While the total envelope binding antibody titers to both subtype B and E envelopes did not differ significantly between the E and B/E plasmas, 67% of B/E plasmas neutralized >50% of the viruses in the panel, and only 14% of E plasmas showed this broadened neutralizing activity. These data suggest that dual (B/E) V3 loop reactivity may be a marker of broader immune recognition of HIV envelope epitopes in subtype E-infected patients. V3 loop antibody, perhaps in conjunction with antibodies to additional epitopes, may play a role in neutralization of virus isolates from Thailand.

HIV-1 seroprevalence, risk factors, and preventive behaviors among women in northern Thailand

To study HIV-1 seroprevalence, risk factors, and preventive behaviors among reproductive-age women in northern Thailand, 804 consenting women who were identified postpartum or who were visiting family planning clinics were interviewed and tested during 1998 to 1999. Almost all women were currently married and had been pregnant more than once. Their median age was 27 years. HIV-1 seroprevalence was 3.1% overall and was higher in women aged between 25 and 29 years (5.9%), having had > or =2 lifetime sex partners (6.5%), or whose current marriage had lasted for < or =1 year (7.0%). No woman reported HIV risk factors other than heterosexual sex. Most (76%) HIV-infected women reported no casual sex partners and, therefore, had likely acquired the infection from their husbands. HIV testing and partner communications were common, but only 2% of couples used condoms consistently in the prior 6 months. Nearly half of these women perceived themselves at no or low risk for HIV infection; these women were less likely to have taken preventive actions. To prevent HIV transmission in stable partnerships in this population, additional efforts are needed to increase HIV testing and condom use, to improve women's negotiation skills, and to develop new methods that do not require partner cooperation such as vaginal microbicides or vaccines.

Empirical Bayes approach to estimating the number of HIV-infected individuals in hidden and elusive populations

In this paper we estimate the numbers of intravenous drug users (IVDUs) and commercial sex workers (CSWs) in Thailand infected with human immunodeficiency virus (HIV) who have not developed acquired immunodeficiency syndrome (AIDS) directly from the semi-annual HIV serosurveillance data of Thailand from June 1993 to June 1995. We propose a 'generalized removal model for open populations' for estimating HIV-infected population size within a hidden, elusive, and perhaps high-risk population group, for all sampling time when capture probabilities vary with time. We apply empirical Bayes methodology to the generalized removal model for open populations by using the Gibbs sampler, a Markov chain Monte Carlo method. No assumption on the size of the hidden population in question is needed to implement this procedure. The statistical method proposed here requires very little computing and only a minimum of two sets of serosurvey data to obtain an estimate, thereby providing a simple and viable option in epidemiological studies when either powerful computing facilities or abundant sampling data are lacking.

A phase I/II trial of HIV SF2 gp120/MF59 vaccine in seronegative thais.AFRIMS-RIHES Vaccine Evaluation Group. Armed Forces Research Institute of Medical Sciences and the Research Institute for Health Sciences

Fifty-two human immunodeficiency virus type 1, seronegative Thai adults from the community were enrolled in a double-blind, placebo controlled, phase I/II trial of HIV SF2 gp120/MF59 vaccine to determine the safety and immunogenicity of this recombinant, B clade, HIV envelope protein vaccine. Twenty-six subjects were enrolled at each of two sites in Thailand, Bangkok and Chiang Mai. Twelve subjects received placebo and 40 subjects received vaccine (50 microg). Subjects were immunized according to one of two schedules, 0, 1 and 4 or 0, 1 and 6 months. The frequency of adverse reactions was not different between placebo and vaccine subjects, nor between immunization schedules. Of vaccinees, all developed high-titer binding antibody to the immunogen (rgp120), 39 developed neutralizing antibody (NA) responses against homologous virus (HIV-1(SF2)), and 22 developed NA against heterologous virus (HIV-1(MN)). No subject demonstrated intercurrent HIV infection, however screening EIA reactivity occurred in 27% of recipients. Thus, this candidate HIV vaccine was found to be safe and immunogenic in Thai adults, laying the foundation for development of a subtype E construct in this population.

Condom availability for HIV/STD prevention

Condom availability is a structural intervention that increases access to condoms. It is the most important strategy for the prevention of the sexual transmission of HIV/STDs in developing countries. While it is an integral component of many prevention programs, it is considered controversial in high school settings and its role in a variety of HIV/STD prevention interventions has been understudied, understated, and/or unacknowledged. Condom availability as an HIV/STD prevention strategy needs to be reprioritized and should be considered a critical foundation of all programs to prevent the sexual transmission of HIV.

Differences in sexual behaviour between HIV-infected pregnant women and their husbands in Bangkok, Thailand

In a Bangkok antenatal clinic, we interviewed 102 HIV-infected pregnant women and their husbands, 30% of whom were HIV-negative. We evaluated these data by matched and unmatched analysis, compared men and women in stable couple relationships on a number of sociodemographic and risk factor indicators and investigated further whether there were any differences in sociodemographic or risk factor profiles between HIV-serodiscordant couples and seroconcordant couples. When compared to wives, more of the husbands were working (p = 0.001), earning more money (p = 0.001), had had more than two sex partners (p = 0.001) and had had syphilis (p = 0.001). Serodiscordant couples did not differ greatly from seroconcordant couples except that women married to HIV-negative men were more likely to have been divorced or separated than their husbands which was not the case for women married to HIV-positive men (p = 0.02). There was poor agreement between husband and wife reports of husband risk behaviour and this did not differ between concordant and discordant couples. These findings suggest that assessment of risk and counselling of Thai women is incomplete without information on the HIV status and risk behaviour of her partner. Prevention strategies to decrease heterosexual transmission among couples need to target both the man and the woman.

Seroprevalence of HIV among female sex workers in Bangkok: evidence of ongoing infection risk after the "100% condom program" was implemented

BACKGROUND

After implementation in 1991 of a nationwide campaign to promote condom use during commercial sex, HIV-1 seroprevalence among young men began to decrease in 1994. However, it is unknown to what degree female sex workers (FSWs) have been protected from infection.

METHODS

FSWs attending a government clinic in Bangkok in 1997 and 1998 were interviewed, counseled, and tested for evidence of prior syphilis by Treponema pallidum hemagglutination assay (TPHA) and for HIV-1 antibodies.

RESULTS

Among the 500 participants, women who began sex work more recently reported less risky sex behavior when they were first potentially exposed to HIV infection, and TPHA reactivity rates were lower among these women. However, their HIV infection rates were higher. HIV seroprevalence was 5.5% among 91 women who began sex work before 1989, 8.0% among 87 women who began during 1990 to 1993, and 12.5% among 322 women who had begun since 1994.

CONCLUSIONS

Although condom use is critical to HIV prevention, women in this study who began sex work after the condom promotion campaign was implemented were still at high risk for HIV infection. Additional measures are needed to prevent HIV infection among the many young women who initiate or continue to engage in commercial sex.

HIV-1 seroprevalence among childbearing women in northern Thailand: monitoring a rapidly evolving epidemic

OBJECTIVES

To describe trends in prevalence of HIV-1 infection among women giving birth at Chiang Rai Hospital (CRH) and to assess risk factors associated with HIV infection in this population.

DESIGN

Analysis of hospital registry data for all deliveries at CRH from 1990 to mid-1997.

METHODS

From 1990 to mid-1997, women giving birth at CRH were tested for HIV-1 infection using enzyme immunoassay (EIA); positive sera were confirmed using a different manufacturer's EIA. Demographic and clinical data were abstracted from delivery-ward log books.

RESULTS

Data from 40723 deliveries indicated that overall HIV-1 seroprevalence increased sharply, from 1.3% in 1990 to a peak of 6.4% in 1994, and then declined to 4.6% in the first 6 months of 1997. Prevalence was highest, at 7.0%, among young (age < or = 24 years) primigravidas, compared with 2.4% among older (age > or = 25 years) multigravidas. When we controlled for age, prevalence declined 40% from 1994 to 1997 among young primigravidas (95% confidence interval for percentage reduction, 16-57). Amongst older multigravid women, prevalence was consistently lower but increased steadily from 2.7% in 1994 to 3.4% in 1997.

CONCLUSIONS

A rapid rise in HIV prevalence in childbearing women was followed by a sharp decline among young primigravidas. In each year, the prevalence was highest among young primigravidas. They may be the best subgroup of pregnant women for monitoring HIV epidemic trends, but they also represent a challenging prevention priority that will require its own targeted interventions.

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.

HIV-1 and other sexually transmitted infections in a cohort of female sex workers in Chiang Rai, Thailand

OBJECTIVES

To determine demographic and behavioural factors and sexually transmitted infections (STIs) associated with prevalent HIV-1 infection among brothel based and other female sex workers (FSWs) in Chiang Rai, northern Thailand.

METHODS

Data were collected from questionnaires, physical examinations, and laboratory evaluations on Thai FSWs enrolled in a prospective cohort study in Chiang Rai, Thailand, from 1991 to the end of 1994.

RESULTS

HIV-1 seroprevalence was 32% among 500 women: 47% for 280 brothel workers and 13% for 220 other FSWs (p < 0.001); 96% of infections were due to HIV-1 subtype E. At enrolment, other STIs were common: chlamydia, 20%; gonorrhoea, 15%; active syphilis (serological diagnosis), 9%; genital ulcer, 12%; seroreactivity to Haemophilus ducreyi, 21%, and herpes simplex virus type 2 (HSV-2), 76%. On multiple logistic regression analysis, HIV-1 was associated with brothel work, birth in upper northern Thailand, initiation of commercial sex at < 15 years of age, syphilis, HSV-2 seropositivity, and genital ulcer.

CONCLUSIONS

Young Thai FSWs working in brothels in northern Thailand in the early phase of the HIV epidemic have been at very high risk for HIV-1 infection and several other STIs. Programmes are needed to prevent girls and young women from entering the sex industry and to reduce the risk of infection with HIV-1 and other STIs.

In the company of friends: peer influence on Thai male extramarital sex

We explore some of the key social dynamics underlying patterns of male extramarital heterosexual behavior in Thailand. We analyze transcripts of focus group discussions and focused individual interviews conducted during 1993 and 1994 with married men and women living in both urban and rural areas of central Thailand. We discern several pathways of peer influence on extramarital commercial sex patronage that are common across our sites and interpret these peer effects in light of contemporary theories of social influence and sexual behavior.

Nationwide surveillance of HIV-1 prevalence and subtype in young Thai men

As part of routine surveillance, an HIV-1 serosurvey of 366,074 members of successive cohorts of young Thai men entering service with the Royal Thai Army (RTA) was conducted between November 1989 and November 1995. We analyzed regional and temporal trends in HIV-1 seroprevalence in young men in Thailand and determined the proportion of infections resulting from subtypes E and B in this population in 1992 and 1995. The prevalence in 1992 was compared with that in 1995 by region and demographic group. The HIV-1 subtype was determined in a random sample of HIV-1-positive specimens in 1992 and 1995 using a V3 peptide enzyme immunoassay. From a peak of 3.7% in 1993, overall seroprevalence declined to 3.0% in 1994 and further in 1995 to 2.5%. Between 1992 and 1995, the absolute decrease in seroprevalence was greatest in the upper North (from 12.5% to 5.3%), where the prevalence has been the highest. Overall, 96.9% and 95.9% of typable specimens were determined to be subtype E in 1992 and 1995, respectively. Decline in HIV-1 seroprevalence among young men in Thailand has continued, which suggests that HIV control programs in Thailand may have been successful in decreasing spread of HIV-1. Almost all HIV-1 infections resulted from subtype E.

HIV-1 seroconversion in a prospective study of female sex workers in northern Thailand: continued high incidence among brothel-based women

OBJECTIVES

To determine the incidence of HIV-1 infection, temporal trends in incidence, and risk factors for seroconversion in a cohort of female commercial sex workers (CSW) in upper northern Thailand, the region of Thailand with the highest rates of HIV-1 infection.

METHODS

CSW were enrolled from 1991 through 1994 and evaluated prospectively with interviews, physical examination, testing for sexually transmitted diseases (STD), and serologic testing for HIV-1 infection.

RESULTS

The incidence of HIV-1 seroconversion in the first year of follow-up was 20.3 per 100 person-years among 126 brothel-based CSW and 0.7 per 100 person-years among 159 other CSW who worked in other venues such as bars or massage parlors. Incidence remained elevated among brothel-based CSW who were enrolled later in the study compared with those who enrolled earlier. Through 1996, 30 women seroconverted. In a multivariable proportional hazards model, seroconversion was significantly associated (P < 0.05) with brothel-based sex work (adjusted risk ratio, 7.3) and Chlamydia trachomatis cervical infection (adjusted risk ratio, 3.3).

CONCLUSION

Despite national HIV control efforts and declining rates of infection among young men in Thailand, brothel-based CSW may continue to be at high risk for HIV-1 infection. Additional efforts are needed to provide alternative economic choices for young women, to ensure universal condom use during commercial sex, and to develop new prevention technologies.

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.

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.

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.

Evaluation of a targeted HIV prevention programme among female commercial sex workers in the south of Thailand

OBJECTIVE

To evaluate a targeted HIV prevention programme among female commercial sex workers (CSWs) in the south of Thailand.

SUBJECTS AND METHODS

A pretest-post-test comparison group study was carried out in Sungai Kolok and Betong between June and December 1994. In June 408 CSWs were entered in Sungai Kolok (the intervention area) and 343 CSWs were enrolled in Betong (the comparison area). In December 1994, 416 women were enrolled in Sungai Kolok and 342 in Betong. Of these women 37% (n = 283) also participated in the June survey. All women completed an oral interview and blood samples were collected for HIV serology. The intervention programme consisted of an informational and educational campaign and peer educator training.

RESULTS

Increase in knowledge and perceived vulnerability was more pronounced in the intervention area but did not translate into a greater increase in condom use. Refusal of customers unwilling to use a condom and manager support in doing so were the only factors independently related to positive changes in condom use. HIV prevalence (approximately 20%) and incidence (approximately 4.2 per 100 women years) were the same in both study locations. Women in the intervention area reported significantly fewer customers and income from sex work, possibly as a result of a coincidental police campaign to suppress (child) prostitution.

CONCLUSIONS

HIV incidence among CSWs in the south of Thailand is still high. Prevention programmes should focus on improvement of negotiation and refusal skills and manager support in using condoms.

Change in sexual behaviour and decline in HIV infection among young pregnant women in urban Uganda

OBJECTIVE

To describe sexual behaviour that may partly explain a decline in HIV seroprevalence in pregnant women in urban settings in Uganda, East Africa.

SETTINGS

Two major urban districts in Uganda.

METHODS

Repeated population-based behavioural surveys in 1989 and 1995, and repeated HIV serological surveys in consecutive pregnant women attending antenatal clinics from 1989 to 1995.

RESULTS

During the study period, a 2-year delay in the onset of sexual intercourse among youths aged 15-24 years and a 9% decrease in casual sex in the past year in male youths aged 15-24 years were reported. Men and women reported a 40% and 30% increase in experience of condom use, respectively. In the same study area, over the same period, there was an overall 40% decline in the rates of HIV seroprevalence among pregnant women attending antenatal clinics. It can be hypothesized that the observed declining trends in HIV correspond to a change in sexual behaviour and condom use, especially among youths.

CONCLUSIONS

This is the first report of a change over a period of 6 years in male and female sexual behaviour, assessed at the population level, that may partly explain the observed decline in HIV seroprevalence in young pregnant women in urban Uganda. This result should encourage AIDS control programmes to pursue their prevention activities.

Medication use by female sex workers for treatment and prevention of sexually transmitted diseases, Chiang Rai, Thailand

BACKGROUND

Female sex workers (FSWs) in Thailand are at high risk for sexually transmitted diseases (STDs). Although regular attendance at public STD clinics is required, FSWs may frequently use medications obtained in the community for STDs.

OBJECTIVES

To determine the frequency of use of medications for STDs from sources other than public STD clinics among FSWs in Thailand and to describe factors associated with such medication use.

METHODS

A cross-sectional survey of FSWs attending the public STD clinic in Chiang Rai, Thailand, was performed.

RESULTS

Of the 200 FSWs interviewed, 55% had ever used medications to treat or prevent STDs from a source other than a public STD Clinic, and 36% had done so in the prior year. Most use (79%) was to treat STD symptoms, and medication was most frequently obtained directly from a pharmacy (54%). This use of community medication for STDs was associated with younger age, non-Thai ethnicity, seeking STD treatment during the current clinic visit, and brothel-based sex work.

CONCLUSIONS

Use of medications from various sources in the community was common among these FSWs. Further research is needed to determine the appropriateness of this treatment. Innovative methods to ensure adequate quality STD care by community providers and to improve the health-care-seeking behaviors of these high-risk women are needed.

Trends in HIV-1 prevalence may not reflect trends in incidence in mature epidemics: data from the Rakai population-based cohort, Uganda

OBJECTIVES

To assess whether trends in serial HIV-1 prevalence reflect trend in HIV incidence, and to decompose the effects of HIV-1 incidence, mortality, mobility and compliance on HIV-1 prevalence in a population-based cohort.

DESIGN

Two-year follow up (1990-1992) of an open cohort of all adults aged 15-59 years, resident in a sample of 31 representative community clusters in rural Rakai District, Uganda.

METHODS

A detailed household enumeration was concluded at baseline and in each subsequent year. All household residents were listed, and all deaths and in- and out-migrations that occurred in the intersurvey year wee recorded. In each year, all consenting adults were interviewed and provided a serological sample; 2591 adults aged 15-59 years were enrolled at baseline.

RESULTS

HIV prevalence among adults declined significantly 1990 and 1992 (23.4% at baseline, 21.8% in 1991, 20.9% in 1992; P < 0.05). Declining prevalence was also observed in subgroups, including young adults aged 15-24 years (from 20.6 to 16.2% over 3 years; P < 0.02), women of reproductive age (from 27.1 to 23.5%; P < 0.05), and pregnant women (from 25.4 to 20.0%; not significant), However, HIV incidence did not change significantly among all adults aged 15-59 years (2.1 +/- 0.4 per 100 person-years of observation (PYO) in 1990-1991 and 2.0 +/- 0.3 per 100 PYO in 1991-1992], nor in population subgroups. HIV-related mortality was high (13.5 per 100 PYO among the HIV-positive), removing more infected persons that were added by seroconversion. Net out-migration also removed substantial numbers of HIV-positive individuals.

CONCLUSIONS

In this mature HIV epidemic, HIV prevalence declined in the presence of stable and incidence. HIV-related mortality contributed most to the prevalence decline. Prevalence was not an adequate surrogate measure of incidence, limiting the utility or serial prevalence measures in assessing the dynamics of the HIV epidemic and in evaluating the impact of current preventive strategies.

Empirical evidence for the severe but localized impact of AIDS on population structure

Despite considerable speculation on the demographic impact of AIDS, there has been, until now, little scientific evidence to establish its existence or scale. Because of the widespread implications of these predictions, methods to combine demography and epidemiology to study empirical situations have been an urgent priority. This study derives the extent and mechanisms of demographic impacts of AIDS from routine data (the 1991 census) in a severely affected country, Uganda. Three characteristics are of particular note: first, the emergence of demographic impacts much earlier than previously estimated; second, their localization with negative population growth at parish but not at district or national scales; third, a greater impact on the number of children than previously predicted, due as much to changes in population fertility as mortality. The emergence of demographic impacts at this stage highlights original aspects of the interdependence of HIV infection and demographic growth not previously recorded and the need to target preventive interventions to youth in developing countries.

Universal precautions: costs for protective equipment

BACKGROUND

The amount and costs of protective equipment used to implement universal precautions in Thailand have not previously been studied.

METHODS

A cross-sectional study was done to determine the frequency of clinical and laboratory procedures requiring universal precautions and the amount of protective equipment needed for each.

RESULTS

The study was performed in 24 government hospitals in Thailand in December 1993. Totaling 6549 beds, these hospitals had provided service to 357,391 inpatients and 3,411,122 outpatients during the previous year. The annual number of procedures performed in these hospitals was estimated at 17.5 million, with expenditures for protective equipment of $2.4 million (U.S.) per year. The average overall cost for protective equipment was U.S. $5.37 for one inpatient stay and U.S. $0.15 for one outpatient visit. The projected national expense for these barriers was U.S. $41.5 million per annum. The cost for these barriers after the implementation of universal precautions was 2.5 times the cost before implementation.

CONCLUSIONS

Overuse of sterile and examination gloves and gowns and underuse of heavy-duty gloves, masks, aprons, goggles, and boots were discovered during the study. Appropriate use of disposable and reusable universal precautions equipment would free health care dollars for other purposes.

Changes in sexual behavior and a decline in HIV infection among young men in Thailand

BACKGROUND

In Thailand the epidemic of human immunodeficiency virus (HIV) infection is of recent origin. Because of the high seroprevalence of HIV among sex workers, the Ministry of Public Health began a program in 1990 and 1991 to promote the use of condoms during commercial sex. We evaluated the effect of this and other programs to prevent HIV infection in Thailand.

METHODS

Using direct interviews, we studied five cohorts of 21-year-old men from northern Thailand who were conscripted into the army by a lottery in 1991, 1993, and 1995. In all, 4311 men were tested for HIV antibodies by enzyme-linked immunosorbent assay, with confirmation by Western blot assay.

RESULTS

In the 1991 and 1993 cohorts, the prevalence of HIV infection was 10.4 to 12.5 percent. In 1995, it fell to 6.7 percent (P < 0.001). The seroprevalence was only 0.7 percent among men who did not have sexual relations with a sex worker before 1992. Over the study period, the proportion of men who reported having sexual relations with a sex worker fell from 81.4 percent to 63.8 percent (P < 0.001). From 1991 to 1995, the men's reported use of condoms during the most recent sexual contacts with sex workers increased from 61.0 percent to 92.5 percent (P < 0.001); and in 1995, 15.2 percent of men had a history of a sexually transmitted disease, as compared with 42.2 percent in 1991 (P < 0.001).

CONCLUSIONS

Public health programs in Thailand have led to substantial changes in sexual behavior among young men, especially an increased use of condoms, and the rate of new HIV infections has declined.

Correlates of HIV-1 seropositivity among young men in Thailand

Geographic and demographic correlates of risk for HIV-1 seropositivity were studied in 120,216 young men selected by lottery for service in the Royal Thai Army (RTA). The study population consisted of men selected between November 1991 and May 1993. Venous blood was collected at induction, and a brief demographic questionnaire was administered. HIV-1 seropositivity was established by Western blot confirmation of duplicate reactive ELISAs. Geographic variable provided the strongest correlate of risk, clearly distinguishing residents of the upper north, Bangkok, and the central region from the northeast. Overall 12.2% of men from the upper north were HIV-positive. Men who had lived in rural areas were at less risk in most regions of the country, but had equal risk in the upper north. Unmarried men and those with less education were at higher risk throughout the country. These data provide valuable information on the prevalence of HIV infection in one segment of the general population. Continued surveillance of this group will facilitate evaluation of Thailand's response to the epidemic.