Rising prevalence of HIV infection and associated risk factors among young Thai Men in 2018.

The prevalence of HIV among young Thai men stabilized at 0.5% from 2005 to 2011. A cross-sectional study was conducted among the male army conscripts in 2018 at 36 military training units nationwide. All new conscripts in each selected unit were invited to participate in the study. Questionnaires were used to determine risk factors to HIV infection that had been developed from related risk factors studies among young Thai men. Among 4629 participants, 44 (1.0%) HIV positive individuals were identified. The proportion subject reporting a history of sex with another man was 10.1%. The prevalence of HIV infection among men who have sex with men (MSM) was 4.0%. The proportion of consistent condom use with a male partner was 39.7%. The risk factors of HIV infection included having sex with another man, history of sexually transmitted infection and history of sex in exchange for gifts/money. Only 1.4% of MSM used pre-exposure prophylaxis (PrEP). HIV prevention programs including PrEP in Thailand should be emphasized among MSM in both rural and urban settings.

Prevention of mother-to-child transmission of hepatitis B virus: protocol for a one-arm, open-label intervention study to estimate the optimal timing of tenofovir in pregnancy.

INTRODUCTION: Hepatitis B virus (HBV) remains a public health threat and the main route of transmission is from mother to child (MTCT). Tenofovir disoproxil fumarate (TDF) treatment can reduce MTCT of HBV although the optimal timing to attain undetectable HBV DNA concentrations at delivery is unknown. This protocol describes the procedures following early initiation of maternal TDF prior to 20 weeks gestation to determine efficacy, safety and feasibility of this approach in a limited-resource setting. METHODS AND ANALYSES: One hundred and seventy pregnant women from the Thailand-Myanmar border between 12 and <20 weeks gestational age will be enrolled into a one-arm, open-label, TDF treatment study with cessation of TDF 1 month after delivery. Sampling occurs monthly prenatal, at birth and at 1, 2, 4 and 6 months post partum. Measurement of tenofovir concentrations in maternal and cord plasma is anticipated in 10-15 women who have detectable HBV DNA at delivery and matched to 20-30 women with no detectable HBV DNA. Infant HBsAg status will be determined at 2 months of age and HBV DNA confirmed in HBsAg positive cases. Adverse events including risk of flare and adherence, based on pill count and questionnaire, will be monitored. Infants will receive HBV vaccinations at birth, 2, 4 and 6 months and hepatitis B immunoglobulin at birth if the mother is hepatitis B e antigen positive. Infant growth and neurodevelopment at 6 months will be compared with established local norms. ETHICS AND DISSEMINATION: This study has ethical approval by the Ethics Committee of the Faculty of Tropical Medicine, Mahidol University (FTM ECF-019-06), Johns Hopkins University (IRB no: 00007432), Chiang Mai University (FAM-2559-04227), Oxford Tropical Research Ethics Committee (OxTREC Reference: 49-16) and by the local Tak Community Advisory Board (TCAB-02/REV/2016). The article will be published as an open-access publication. TRIAL REGISTRATION NUMBER: NCT02995005, Pre-results.

Prevalence of HIV infection and related risk factors among young Thai men between 2010 and 2011.

INTRODUCTION: Understanding the current epidemiology of human immunodeficiency virus (HIV) infection in Thailand will facilitate more effective national HIV prevention programs. This study aimed to determine the prevalence and risk factors for HIV infection among young Thai men. METHODS: A total survey was conducted of Royal Thai Army new conscripts, participating in the national HIV surveillance in November 2010 and May 2011. Behavioral risk factors for HIV infection were determined using a standardized survey questionnaire in the total study population and men who have sex with men (MSM) subgroup. RESULTS: A total of 301 (0.5%) HIV infected young Thai men were identified from the total study population (63,667). Independent risk factors associated with HIV infection among the total study population included being single (adjusted Odds Ratio [AOR] 1.6, 95% Confidence Interval [CI] 1.1-2.2), having no formal education (AOR 6.5, 95% CI 2.3-18.4) or a bachelor's degree (AOR 1. 8, 95% CI 1.0-3.0), engaging in bisexual (AOR 3.7, 95% CI 2.4-5. 6) or exclusively homosexual activity (AOR 14.4, 95% CI 10.4-19.8), having a history of Sexually Transmitted Infection (STI) (AOR 2.3, 95% CI 1.6-3.3) and having sex in exchange for gifts/money (AOR 2.0, 95% CI 1. 5-2.8). A total of 4,594 (7.9%) MSM were identified, of which 121 (2.6%) were HIV infected. The prevalence of HIV infection among MSM in urban (2.8%) and rural (2.4%) areas were relatively comparable (p-value = 0.44). Of the identified MSM, 82.5% reported having sexual desire with females only. Risk factors associated with HIV infection in the MSM subgroup included living in the western region (AOR 3.5, 95% CI 1.2-10.4), having a bachelor's degree (AOR 2.7, 95% CI 1.2-5.7), having a history of exclusive receptive (AOR 3.6, 95% CI 1.6-7.7) or versatile anal sex (AOR 4.7, 95% CI 3.0-7.5) and history of having sex in exchange for gifts/money (AOR 2.3, 95% CI 1.5-3.5). CONCLUSION: The prevalence of HIV infection among young Thai men has continued to be below 0.5% in 2010 and 2011. High risk sexual activity, including MSM, played a major role in the HIV epidemic among this population. Effective HIV prevention programs should cover MSM who have heterosexual desire as well as having sex in exchange for gifts/money and be implemented in both urban and rural areas.

Durable HIV Suppression Among People Who Inject Drugs From a Community-Based Cohort Study in Baltimore, Maryland, 1997-2017.

People who inject drugs (PWID) face disparities in human immunodeficiency virus (HIV) treatment outcomes and may be less likely to achieve durable viral suppression. We characterized transitions into and out of viral suppression from 1997 to 2017 in a long-standing community-based cohort study of PWID, the AIDS Link to Intravenous Experience (ALIVE) Study, analyzing HIV-positive participants who had made a study visit in or after 1997. We defined the probabilities of transitioning between 4 states: 1) suppressed, 2) detectable, 3) lost to follow-up, and 4) deceased. We used multinomial logistic regression analysis to examine factors associated with transition probabilities, with a focus on transitions from suppression to other states. Among 1,061 participants, the median age was 44 years, 32% were female, 93% were African-American, 59% had recently injected drugs, and 28% were virologically suppressed at baseline. Significant improvements in durable viral suppression were observed over time; however, death rates remained relatively stable. In adjusted analysis, injection drug use and homelessness were associated with increased virological rebound in earlier time periods, while only age and race were associated with virological rebound in 2012-2017. Opioid use was associated with an increased risk of death following suppression in 2012-2017. Despite significant improvements in durable viral suppression, subgroups of PWID may need additional efforts to maintain viral suppression and prevent premature mortality.

Long-term Antibody Persistence After Hepatitis E Virus Infection and Vaccination in Dongtai, China.

BACKGROUND: Hepatitis E virus (HEV) is of global significance. HEV is a common cause of acute hepatitis in China. One of the major unanswered questions about HEV is the persistence of antibodies after infection and vaccination. METHODS: We examined antibody persistence 6.5 years after HEV exposures through natural infection and vaccination. Ninety-seven vaccine recipients and 70 individuals asymptomatically infected with HEV enrolled in the phase III HEV239 vaccine trial in Dongtai, China, were revisited. RESULTS: Antibody loss was 23.4% (95% confidence interval [CI], 17.1%-30.5%), with a nonsignificantly higher percentage of loss among those naturally infected (30.0%; 95% CI, 19.6%-42.1%) than those vaccinated (18.6%; 95% CI, 11.4%-27.7%; P = .085). Age and gender were not associated with antibody persistence. Only 2 people (1.2%) self-reported medically diagnosed jaundice or hepatitis-like illness in the last 10 years, both of whom had persistent antibodies. Contact with a jaundice patient and injectable contraceptive use were marginally associated with loss of detectable anti-HEV antibodies (P = .047 and .082, respectively), whereas transfusion was marginally associated with antibody persistence (P = .075). CONCLUSIONS: Antibody loss was more common among those naturally infected compared with those vaccinated. However, none of the characteristics examined were strongly associated with antibody loss, suggesting that factors not yet identified may play a more important role in antibody loss. Long-term postvaccination antibody persistence is currently unknown and will be an important consideration in the development of policies for the use of the highly efficacious HEV vaccine. ClinicalTrials.gov registration. NCT01014845.

An outbreak of HIV infection among people who inject drugs linked to injection of propofol in Taiwan.

INTRODUCTION: The aim of this study was to report an HIV outbreak related to propofol-injection and the impact of regulating propofol on the HIV epidemic among people who inject drugs (PWID). METHODS: A retrospective cohort study of 252 PWID who were diagnosed with an HIV infection between 2014 and 2017 in Taiwan. The propofol information was collected by routine epidemic surveillance and interviews. We linked several national databases to collect other related factors, including methadone maintenance treatment (MMT) attendance and incarceration. The serums were tested for recent infection by the LAg-avidity EIA assay and relationship of the trains by the Phylogenetic tree analysis. Analyses were conducted using the R Surveillance package for retrospective modeling for outbreak detection. A multiple logistic regression was used to evaluate the association between propofol-injection and other related factors. RESULTS: There were 28 cases reported with propofol-injection, all of which were reported in Central Taiwan. A total of 11 (50%) cases among 22 propofol-injectors with serums were recent infections, which were higher than that 33 (23.4%) of non-propofol group. The phylogenetic tree indicated that 6 propofol-injectors were grouped together with the same cluster in circular. The HIV epidemic curve among PWID revealed an outbreak of 82 in 2015, which then decreased to 43 in 2016 after propofol began to be regulated as a Schedule 4 controlled drug in August 2015. In a multiple logistic regression, attendance at methadone clinics was associated with a significantly higher risk for propofol-injection (adjusted OR = 2.43, 95% CI = 0.98-5.98), and HIV reported in the year 2015 was associated with an increased risk of propofol-injection (adjusted OR = 4, 95% CI = 1.08-14.86). CONCLUSIONS: Our data indicate that the government regulation of propofol as a controlled drug strategy was associated with significant reduction in the spread of HIV among PWID.

Probable transmission of hepatitis E virus (HEV) via transfusion in the United States.

BACKGROUND: Hepatitis E virus (HEV) can inapparently infect blood donors. To assess transfusion transmission of HEV in the United States, which has not been documented, a donor-recipient repository was evaluated. STUDY DESIGN AND METHODS: To identify donations that contained HEV RNA and were linked to patient-recipients with antibody evidence of HEV exposure, we assayed samples from the Retrovirus Epidemiology Donor Study (REDS) Allogeneic Donor and Recipient repository that represents 13,201 linked donations and 3384 transfused patients. Posttransfusion samples, determined to contain IgG anti-HEV by enzyme-linked immunosorbent assay, were reassayed along with corresponding pretransfusion samples for seroconversion (incident exposure) or at least fourfold IgG anti-HEV increase (reexposure). HEV-exposed patients were linked to donations in which HEV RNA was then detected by reverse-transcription quantitative polymerase chain reaction, confirmed by transcription-mediated amplification, and phylogenetically analyzed as subgenomic cDNA sequences. RESULTS: Among all patients, 19 of 1036 (1.8%) who had IgG anti-HEV before transfusion were reexposed; 40 of 2348 (1.7%) without pretransfusion IgG anti-HEV seroconverted. These 59 patients were linked to 257 donations, 1 of which was positive by reverse-transcription quantitative polymerase chain reaction and transcription-mediated amplification. Plasma from this donation contained 5.5 log IU/mL of HEV RNA that grouped with HEV genotype 3, clade 3abchij. The patient-recipient of RBCs from this donation had a greater than eightfold IgG increase; however, clinical data are unavailable. CONCLUSIONS: This is the first report of probable HEV transmission via transfusion in the United States, although it has been frequently observed in Europe and Japan. Additional data on the magnitude of the risk in the United States are needed.

Epidemiology of Genotype 1 and 2 Hepatitis E Virus Infections.

Hepatitis E virus (HEV) genotypes 1 and 2 are responsible for the majority of acute viral hepatitis infections in endemic areas in South Asia and sub-Saharan Africa. In addition to frequent sporadic illnesses throughout the year, these viruses often cause large epidemics in association with monsoon rains in Asia or during humanitarian crises in Africa. Clinical hepatitis commonly involves adults more often than young children, with an overall mortality of ∼1%. However, the mortality among pregnant women is often 30% or higher. HEV infection in pregnant women frequently leads to infant mortality or premature delivery. Hepatitis E is an important, yet largely neglected, global public health problem.

The finding of casual sex partners on the internet, methamphetamine use for sexual pleasure, and incidence of HIV infection among men who have sex with men in Bangkok, Thailand: an observational cohort study.

BACKGROUND: The finding of casual sex partners on the internet and methamphetamine use have been described as risk factors for HIV infection in men who have sex with men (MSM). However, the interplay between these factors has not been studied prospectively in one design. This study aims to determine the associations between finding casual sex partners on the internet and incident methamphetamine use and HIV infection. METHODS: In this observational cohort study of Thai MSM, we recruited Bangkok residents aged 18 years or older with a history of penetrative male-to-male sex in the past 6 months. Baseline and follow-up visits were done at a dedicated study clinic in central Bangkok. Men were tested for HIV infection at every study visit and for sexually transmitted infections at baseline. Baseline demographics and HIV risk behaviour information were collected at every visit by audio computer-assisted self-interview. We used a descriptive model using bivariate odds ratios to elucidate the order of risk factors in the causal pathway to HIV incidence and methamphetamine use. We used Cox proportional hazard regression analysis to evaluate covariates for incident methamphetamine use and HIV infection. FINDINGS: From April 6, 2006, to Dec 31, 2010, 1977 men were screened and 1764 were found eligible. 1744 men were enrolled, of whom 1372 tested negative for HIV and were followed up until March 20, 2012. Per 100 person-years of follow-up, incidence of methamphetamine use was 3·8 (128 events in 3371 person-years) and incidence of HIV infection was 6·0 (212 events in 3554 person-years). In our descriptive model, methamphetamine use, anal sex, and various other behaviours cluster together but their effect on HIV incidence was mediated by the occurrence of ulcerative sexually transmitted infections. Dual risk factors for both incident methamphetamine use and HIV infection were younger age and finding casual sex partners on the internet. Having ever received money for sex was predictive for incident methamphetamine use; living alone or with a housemate, recent anal sex, and ulcerative sexually transmitted infections at baseline were predictive for incident HIV infection. INTERPRETATION: In MSM in Bangkok, casual sex partner recruitment on the internet, methamphetamine use, and sexually transmitted infections have important roles in sustaining the HIV epidemic. Virtual HIV prevention education, drug use harm reduction, and biomedical HIV prevention methods, such as pre-exposure prophylaxis, could help to reduce or revert the HIV epidemic among MSM in Bangkok. FUNDING: US Centers for Disease Control and Prevention and the Johns Hopkins Fogarty AIDS International Training and Research Program.

A Ten Year Immunopersistence Study of Hepatitis E Antibodies in Rural Bangladesh.

Hepatitis E virus (HEV) is a major cause of acute, viral hepatitis in Southeast Asia. Several studies have suggested that antibody persistence after HEV infection may be transient, possibly increasing the risk of re-infection and contributing to the frequency of outbreaks in HEV endemic regions. The specific conditions under which antibodies to HEV are lost, or "sero-reversion" occurs, are poorly understood. Here, one hundred participants from population-based studies in rural Bangladesh were revisited in 2015, ten years after a documented HEV infection to examine long-term antibody persistence. Twenty percent (95% confidence interval: 12.0, 28.0) no longer had detectable antibodies at follow-up, suggesting that antibodies generally persist for at least a decade after infection in rural Bangladesh. Those who were seronegative at follow-up were generally younger at infection than those who remained positive (14.4 years versus 33.6 years, P > 0.0001). This age-dependent antibody loss could partially explain cross-sectional sero-prevalence data from South East Asia where children have reportedly low antibody prevalence. The results of this study provide new insight into the immunological persistence of HEV infection in a micronutrient deficient rural population of South Asia, highlighting the importance of age at infection in the ability to produce long-lasting antibodies against HEV.

Addressing gaps in international blood availability and transfusion safety in low- and middle-income countries: a NHLBI workshop.

In April 2017, a workshop sponsored by the National Heart, Lung, and Blood Institute, Division of Blood Diseases and Resources, and the Center for Translation Research and Implementation Science was held to discuss blood availability and transfusion safety in low- and middle-income countries (LMICs). The purpose of the workshop was to identify research opportunities for implementation science (IS) to improve the availability of safe blood and blood components and transfusion practices in LMICs. IS describes the late stages of the translational research spectrum and studies optimal and sustainable strategies to deliver proven-effective interventions. Regional working groups were formed to focus on opportunities and challenges in East Africa, Central/West Africa, Middle East and North Africa, Latin America and the Caribbean, Southeast Asia, Western Pacific Asia, Eastern Europe, and Central Asia. The need for an "adequate supply of safe blood" emerged as the major overriding theme. Among the regional working groups, common cross-cutting themes were evident. The majority of research questions, priorities, and strategies fell into the categories of blood availability, blood transfusion safety, appropriate use of blood, quality systems, health economics and budgeting, and training and education in IS. The workshop also brought into focus inadequate country-level data that can be used as the basis for IS initiatives. A mixed approach of needs assessment and targeted interventions with sufficient evidence base to move toward sustainment is an appropriate next step for blood availability and transfusion safety research in LMICs.

Association of killer cell immunoglobulin-like receptors with spontaneous clearance of hepatitis C virus in the Chinese population.

BACKGROUND: Natural killer (NK) cells are critical components in innate immune response to viral infection. Killer cell immunoglobulin-like receptors (KIRs) are involved in regulating the balance of activation or inhibitory function of NK cells. However, the association of KIRs with the spontaneous clearance of hepatitis C virus (HCV) remains unclear in the Chinese population. STUDY DESIGN AND METHODS: A total of 407 HCV-seropositive voluntary blood donors were recruited, including 203 with spontaneous viral clearance and 204 with chronic infection. The presence of KIR genes was detected individually by polymerase chain reaction with sequence-specific primers. Data of HLA and interleukin-28B (IL28B) genotypes were extracted from our previous study. RESULTS: Our results showed that KIR2DL2, 2DS2, 2DL2/2DL3, and 2DL5A-/2DL5B+ were more frequent in subjects with HCV clearance than those with chronic infection (odds ratio [OR], 1.640, p = 0.034; OR, 1.664, p = 0.032; OR, 1.636, p = 0.040; and OR, 2.601, p = 0.012, respectively). Multivariate logistic regression analysis showed that KIR2DL5A-/2DL5B+ associated with HCV clearance (OR, 2.448, p = 0.027), independent of sex, IL28B, and other KIRs. In contrast, KIR2DL3/2DL3 (OR, 0.610, p = 0.034) as well as 2DL3/2DL3+HLA-C1 or C1C1 (OR, 0.580, p = 0.017; and OR, 0.639, p = 0.025, respectively) was found associated with chronic HCV infection. The presence of the homozygous KIR2DL3 with or without its HLA ligand increased the OR of developing chronic HCV infection in the context of IL28B. CONCLUSIONS: In this study we identified KIR2DL5A-/2DL5B+ associated with HCV spontaneous clearance, while KIR2DL3/2DL3, 2DL3/2DL3+HLA-C1, or C1C1 associated with chronic infection. Our study highlighted the fact that the roles of KIR and KIR-HLA contributed to the control of HCV infection by innate immune responses.

Prevalence of chronic hepatitis B and status of HBV care among rural women who planned to conceive in China.

Globally, one third of prevalent chronic hepatitis B (CHB) virus infection (HBV) occurred in China. Assessing the prevalence of CHB infesction and status of HBV-related services among pre-conception women will provide insight into risks of mother to child transmission (MTCT). A cross-sectional analysis of data from the National Free Pre-pregnancy Checkups (NFPC) program in 2010-2014 was conducted. A standardized questionnaire which collected demographic information and enzyme-linked immunosorbent assays (ELISA) which tested serological HBV markers were applied. A total of 16,051,850 rural women aged 15-49 years were included. 5.2% of women were infected with CHB, among whom, 28.6% were also hepatitis B e antigen (HBeAg) positive. The most CHB concentrated places were distributed in southeastern coastal provinces. Women born after 1992 did not experience a higher level of vaccine-induced immunity compared to those born before 1992. Nine in ten rural women with CHB were not aware of their HBV status and a very small proportion of women (0.22%) had received antiviral treatment. Our data demonstrated an overall high-intermediate burden of CHB. Heterogeneity of geographic distribution, high proportion of HBeAg, insufficient awareness of HBV status, and low access to HBV treatment are challenges for preventing the MTCT.

An evaluation of asymptomatic Dengue infections among blood donors during the 2014 Dengue outbreak in Guangzhou, China.

In 2014, an outbreak of dengue virus (DENV) infection led to 45 171 clinical cases diagnosed in Guangdong province, Southern China. However, the potential risk of blood donors asymptomatically infected with DENV has not been evaluated . In the current study we detected anti-DENV IgG antibody and RNA in volunteer Chinese blood donors. We found that anti-DENV IgG antibody was positively detected in 3.4% (51/1500) and two donors were detected as being DENV RNA positive out of 3000 blood samples. We concluded that the presence of potential DENV in blood donors might be potential risk for blood safety. Therefore, screening for DENV infection should be considered in blood donations during a period of dengue outbreak in high epidemic area of China.

Knowledge of and attitudes towards hepatitis B and its transmission from mother to child among pregnant women in Guangdong Province, China.

BACKGROUND: Hepatitis B virus (HBV) infection remains a serious public health problem worldwide. Mother-to-child transmission (MTCT) of HBV is the major mode of transmission in HBV-endemic areas, including China, where little is known about pregnant women's knowledge of and attitudes towards HBV infection and MTCT. METHODS: A cross-sectional survey, conducted in pregnant women in Guangdong Province, China, measured HBV knowledge and attitudes using a questionnaire, at one tertiary and two rural hospitals. RESULTS: The total response rate was 94.5% (737/780). Of the 11 knowledge questions, the mean score was 6.73 ± 3.04 (mean ± SD). Most pertinent to preventing MTCT, 53.3% of the respondents did not know that HBV can be transmitted through unprotected sexual intercourse and nearly 20% did not know that HBV can be transmitted from mother to infant. The results of the four attitude questions was better with 83% and 85% being willing to be screened for HBV and let their baby receive HBV vaccine and HBIg, respectively. However, only 16.5% of respondents agreed that they would be willing to take drugs that are known not to harm the fetus to prevent MTCT of HBV. In multivariable analysis, higher education level was associated with better knowledge and attitude scores. CONCLUSIONS: Knowledge about HBV among pregnant women was poor and needs to be improved to prevent MTCT of HBV. Health education needs to be directed towards pregnant mothers, particularly less educated mothers, in high HBV endemicity settings.

Development of an oral fluid immunoassay to assess past and recent hepatitis E virus (HEV) infection.

BACKGROUND: Hepatitis E virus (HEV) infection causes significant morbidity and mortality worldwide, particularly among pregnant women. In clinical settings blood-based testing protocols are commonly used to diagnose HEV infection, but in community settings such invasive sampling can hinder study participation and limit discovery of the ecology and natural history of HEV infection. Oral fluid is a non-invasive biospecimen that can harbor pathogen-specific antibodies and has the potential to replace blood-based testing protocols. OBJECTIVES: To develop an immunoassay to assess past and recent HEV infection that uses oral fluid instead of serum or plasma. METHODS: The assay was validated using paired oral fluid and serum samples collected from 141 patients who presented either with (n=76) or without (n=65) symptoms of acute viral hepatitis at a clinical diagnostics center in Dhaka, Bangladesh. The sensitivity and specificity of the oral fluid-based immunoassay for HEV IgG (past HEV infection) and HEV IgA (recent HEV infection) antibodies was calculated in reference to Wantai's (Beijing Wantai) serum-based HEV enzyme-linked immunosorbent assay (ELISA) kits for IgG and IgM antibodies, respectively. RESULTS: The sensitivity and specificity of the oral fluid-based immunoassay for HEV-IgG antibodies were 98.7% and 98.4%, respectively. The sensitivity and specificity of the oral fluid-based immunoassay for HEV IgA were 89.5% and 98.3%, respectively. CONCLUSIONS: The high concordance of our non-invasive oral fluid-based immunoassays (HEV IgG and HEV IgA) with commercial high-performance serum HEV ELISA kits (IgG and IgM) means that population-based surveillance of past and recent HEV infection could be expanded to improve understanding of its ecology and natural history.

The Importance of Military Conscripts for Surveillance of Human Immunodeficiency Virus Infection and Risk Behavior in Thailand.

BACKGROUND: The epidemic of Human Immunodeficiency Virus (HIV) infection in Thailand began in 1988 among Injection Drug Users (IDUs) in Bangkok. It soon spread to other populations, especially Female Sex Workers (FSWs) and men attending STD clinics. Routine serologic surveillance for HIV began among military conscripts in 1991. The HIV seroprevalence data from military conscripts provided national surveillance data, since the entire population of 21 year old men were conscripted for 2 years' service in the military by a random process during which 10% of men were selected. Men with a history of injection drug use, or other risk behavior for HIV infection were included. METHODS: HIV seropositive data were analyzed from cohorts of men who were conscripted between 1991 and 2011. Comprehensive behavioral risk data were obtained from the men in these cohorts in order to evaluate behavior changes in response to the evolving HIV/AIDS epidemic. After the Ministry of Public Health established the "100% condom" program in 1991, behavioral data and HIV prevalence and incidence data from military conscripts were important for evaluating the program. RESULTS: The HIV prevalence among Royal Thai Army (RTA) conscripts in 1991 was 4.0%. However, the prevalence was 11.2% among conscripts from the upper Northern provinces. A history of sex with a female sex worker (FSW) was reported by 85.8% of men in 1991; having had sex with a FSW was strongly associated with HIV prevalence, OR=7.40 (3.80-14.0). During the next few years, the HIV prevalence decreased progressively, reports of sex with a FWS declined and the use of condoms during sex increased. Also, the incidence of HIV among conscripts while they were in the army decreased. In the cohort enrolled in 1998, the association between a history of sex with a FSW decreased (OR=2.79; 95% CI 1.0-7.8) however the association between a history of injection drug use and HIV prevalence increased substantially (OR=14.47; 95% Ci 3.5-56.6). Among men in cohorts included in 2008-2009, the HIV prevalence was 0.5%. The most important risk behavior reported by men in these cohorts was sex with another man (MSM), adjusted OR=5.3 (95% CI 3.25- 8.65) whereas history of sex with a FSW was less of a risk. In this cohort 39.5% of HIV infected men reported MSM behavior. CONCLUSION: The sequential data on HIV prevalence and behavioral data from successive large randomly selected national cohorts of young men in Thailand who were conscripted into the Royal Thai Army between 1991 and 2011 has provided critically important surveillance data to monitor the epidemic and evaluate the ongoing effectiveness of public health prevention programs.