The recent epidemiology of HIV and AIDS in Thailand.

PIP: HIV infection is firmly established in the general population of Thailand and will soon exact substantial medical, social, and economic effects at the community and household levels. The primary risk behavior for infection in Thailand is heterosexual intercourse compounded by high levels of other sexually transmitted diseases (STD) and the general cultural acceptance of commercial sex. The June 1993 round of sentinel surveillance for HIV seroprevalence found median and provincial ranges as follows: 35.2% in the range of 13.3-70.8% among IV drug users, 28.7% in the range of 5.1-64.1% among direct sex workers, 7.6% in the range of 0.0-37.3% among indirect sex workers, 8.0% in the range of 0.0-33.0% among men attending STD clinics, 1.4% in the range of 0.0-7.6% among women attending antenatal clinics, and 0.74% in the range of 0.0-8.4% among blood donors. HIV seroprevalence was 4.0% among military conscripts in May 1993. Men and women in Thailand with no other risk factor than sex with a spouse are often at risk of infection with HIV. Urban/rural differentials are minimal, with HIV infection strewn across the country. HIV seroprevalence levels continue to climb despite some success with interventions in slowing the rate of infection among military conscripts and reducing the incidence and prevalence of STDs. Interventions, health care, and coping responses therefore need to be delivered at the community level throughout the country. Although much emphasis has been given to the prevalence of HIV infection in Northern Thailand, seroprevalence data show that other parts of the country will soon experience the same explosion of AIDS cases observed in the North over the past two years.^ieng

Was the 1988 HIV epidemic among Bangkok's injecting drug users a common source outbreak?

OBJECTIVE: To describe and understand the genesis of the explosive 1988 HIV epidemic among Thai injecting drug users (IDU) in Bangkok. DESIGN: Two cross-sectional HIV seroprevalence sample surveys (SP-1 and SP-2) of drug users, including IDU at various stages of treatment. SP-1, a 10-week estimate of prevalence, was conducted by the Bangkok Metropolitan Administration (BMA) in their detoxification clinics from 5 January to 7 March 1988. SP-2 estimated prevalence in 1 week, 12-15 September 1988, in the same 18 BMA clinics. Both surveys included an administered questionnaire that gathered demographic and behavioral information. METHODS: Analysis of HIV prevalence by clinic in both SP-1 and SP-2, and the relationships between demographic data, behavioral variables, arrest history and HIV positivity in SP-1. RESULTS: Data from individual clinics in SP-1 show significant increases in HIV prevalence among IDU sampled from early February 1988. Of IDU sampled in five 'early' clinics before 9 February, 2% were positive; in the 13 'late' clinics sampled from 9 February until 7 March, 27% were positive. By September 1988, however, the early and late clinics were no longer heterogeneous for HIV prevalence. For current IDU, HIV-positivity was associated with the sharing of injection equipment in SP-1 [odds ratio (OR), 1.82; 95% confidence limits (CL), 1.31-2.53] and recent jail or prison stay (OR, 2.15; 95% CL, 1.18-3.98). CONCLUSIONS: The behavioral factors associated with the HIV epidemic among Bangkok's IDU are similar to those described elsewhere. The monthly incidence of 5% from February to September 1988 suggests extensive needle or injection equipment sharing networks among IDU in Bangkok. Additionally, the pattern of HIV-positivity by detoxification clinic over time in early 1988, and then in September 1988 is consistent with a relationship to the prison amnesty of early December 1987. Shortly after that date, an undisclosed number of former IDU, a substantial number of whom were still injecting, and may have become HIV-positive while in custody, returned to resume injecting within existing drug-using networks throughout Bangkok and elsewhere in Thailand.

PIP: This study was undertaken to describe and understand the genesis of the 1988 HIV epidemic among Thai IV drug users (IVDU) in Bangkok. Two cross-sectional HIV seroprevalence sample surveys were conducted of drug users at various stages of treatment at Bangkok Metropolitan Administration (BMA) detoxification clinics. The first survey was a 10-week estimate of HIV prevalence over the period of January 5 to March 7, 1988, involving 1649 drug users who volunteered to give samples of their blood. The second stage survey estimated prevalence over the period September 12-15, 1988, in the same 18 BMA clinics. 1811 drug users volunteered their blood for this latter survey assessment. The monthly incidence of 5% during February-September 188 suggests the existence of extensive needle or injection equipment sharing networks among IVDUs in Bangkok. Moreover, the pattern of HIV-positivity by detoxification clinic over time in early 1988 and in September is consistent with a relationship to the prison amnesty of December 1987 in which an undisclosed number of former IVDUs returned to resume injecting drugs in Bangkok and elsewhere in Thailand.

International epidemiology of HIV and AIDS among injecting drug users.

PIP: HIV/AIDS and iv drug use (IVDU) are of significant multinational scope and growing. Supporting increased IVDU in many countries are countries' geographical proximity to illicit drug trafficking distribution routes, law enforcement efforts which increase the demand for more efficient drug distribution and consumption, and countries' infrastructural and social modernization. Given the failures of intensified law enforcement efforts to thwart the use and proliferation of illegal drugs, countries with substantial IVDU should look away from preventing use to preventing HIV transmission within drug user populations. With HIV seroprevalence rates rapidly reaching 40-50% in some developing country IVDU groups, a variety of prevention programs is warranted. Such programs should be supported and implemented while prevention remains feasible. This paper examines the variation in HIV seroprevalence among IVD users, rapid HIV spread among users, HIV among IVDUs in Bangkok, emerging issues in HIV transmission among IVDUs, non-AIDS manifestations of HIV infection among IVDUs, prevention programs and effectiveness, and harm reduction.^ieng

Condom use with primary partners among injecting drug users in Bangkok, Thailand and New York City, United States.

OBJECTIVE: To determine factors associated with likelihood or failure to use condoms with primary sexual partners among injecting drug users (IDU) in two cities. DESIGN AND METHODS: Interviews were conducted with 601 IDU in Bangkok in 1989 and with 957 IDU in New York City in 1990-1991. Subjects were recruited from drug-use treatment programs and a research storefront. Informed consent was obtained and a World Health Organization standardized questionnaire about AIDS risk behaviors administered by a trained interviewer. RESULTS: A substantial minority (37%) of IDU in Bangkok and a majority (55%) of IDU in New York City reported penetrative intercourse (vaginal, anal or oral) with a primary partner in the 6 months before the interview. Of those reporting penetrative intercourse with a primary partner, only 12% in Bangkok and 20% in New York reported that they always used condoms. Parallel bivariate and multiple logistic regression analyses were conducted to distinguish between subjects who reported always using condoms and subjects who reported unsafe sexual activity with primary partners. The same two factor--knowing that one is HIV-seropositive and talking about AIDS with sexual partners--were most strongly associated with always using condoms with primary partners in both cities. CONCLUSIONS: Programs to prevent sexual transmission of HIV among IDU should provide voluntary and confidential/anonymous HIV counseling and testing, and should facilitate discussions of AIDS and sexual transmission of HIV between IDU and their sexual partners. That the same two factors were associated with always using condoms with primary partners among IDU in these two cities suggests that these factors may also be important in other groups at high risk for HIV.

PIP: Trained interviewers spoke to 957 drug users attending a detoxification program, methadone maintenance program, or a research storefront in New York City in 1990-91 and to 601 drug users attending 17 drug use treatment clinics in Bangkok, Thailand, in the autumn of 1989 as part of a study to identify factors linked to the probability or failure of condom use with primary sexual partners among IV drug users. The participants also received HIV counseling and testing. IV drug users in New York City were more likely to be older (36.2 years vs. 30.1 years; p .001), female (25% vs. 5%; p .001), more ethnically diverse (p .001), and inject cocaine more often (33 injections/month vs. 0.5 injections/month) than those in Bangkok. 44% of drug users in New York City and 33% of those in Bangkok engaged in some unprotected penetrative intercourse with a primary heterosexual partner in the previous 6 months. Of drug users having penetrative sexual intercourse with a primary partner in the previous 6 months, 20% in New York City and 12% in Bangkok always used condoms (p .02). The strongest predictors of condom use among IV drug users from both countries were a previous positive HIV test and talking about AIDS with sexual partners (p = .001 for US; p = .0008 for Bangkok and p = .004 for US; p = .0596 for Bangkok, respectively). These findings indicated that unsafe sexual behavior with primary sexual partners among drug users is still a major source of HIV transmission in these 2 cities. Nevertheless, knowledge of HIV positive status and partner communication concerning AIDS are predictors of condom use shared by both groups. Thus, HIV/AIDS prevention programs should provide confidential HIV testing and counseling for drug users and should encourage frank discussions of AIDS between drug users and primary sexual partners. Peer support for risk reduction among drug users has the potential to facilitate such discussions.

The epidemiology of HIV infection and AIDS in Thailand.

PIP: There were very few AIDS cases reported in Thailand as of 1988, where HIV was introduced relatively late in the course of the AIDS pandemic. Thailand was therefore classified as an epidemiologic pattern III country with regard to the HIV/AIDS pandemic. Also in 1988, however, Thailand experienced a major and rapid increase in HIV prevalence among IV drug users (IVDU). The Thai experience with HIV after the rapid spread first among IVDUs has been successive waves of HIV transmission to female prostitutes, then to their non-IVDU male clients, and then into the non-prostitute wives and girlfriends of these latter men in the general population. Three years after being declared a pattern III country, 300,000 people in Thailand were estimated to be infected out of a population of 55 million. Reasons for this unprecedented rapid spread of HIV infection may eventually come from research on sexual behavior and related diseases given the lack of evidence for human host genetic factors or particularly virulent etiologic agent factors to explain the phenomenon. The reason and dynamics behind the timing and rapidity of the 1988 epidemic among IVDUs for now remains unknown. The authors note that the scenario of HIV transmission observed in Thailand also seems to be unfolding in neighboring countries. HIV infection among female prostitutes and heterosexual men is consistently highest in the northern Thai provinces adjacent to Myanmar and Laos. This paper reviews the epidemiology and prevention of HIV infection and AIDS in Thailand, updating previous reports and commentary, and including previously unpublished or not widely available data.^ieng

Risk factors and HIV seropositivity among injecting drug users in Bangkok.

Bangkok experienced an extremely rapid spread of HIV infection among drug injectors in 1987 and 1988. This study examines risk factors for HIV infection and deliberate risk-reduction efforts by drug injectors. Two subsamples of injecting drug users were recruited in November 1989, a group in drug-use treatment (n = 342) and a group new to the treatment system (n = 259). Subjects were interviewed about AIDS risk behavior, and a blood sample was collected for HIV testing. Seroprevalence was 39 and 27% in the in-treatment sample and the new-to-treatment sample, respectively. The in-treatment sample seroprevalence rate is similar to rates observed 6 and 12 months earlier. Three factors were independently associated with HIV infection: subsample, having been in prison, and sharing injection equipment with two or more individuals in the previous 6 months. Deliberate risk reduction was reported by 92% of individuals, with 59% reporting that they had stopped sharing injection equipment. It appears that large-scale risk reduction has greatly slowed HIV transmission among drug injectors in Bangkok.

Determination of HIV-1 subtypes in injecting drug users in Bangkok, Thailand, using peptide-binding enzyme immunoassay and heteroduplex mobility assay: evidence of increasing infection with HIV-1 subtype E.

OBJECTIVES: To evaluate the sensitivity and specificity of peptide-binding enzyme immunoassay (PEIA) and heteroduplex mobility assay (HMA) for the determination of HIV-1 subtypes B and E; to determine the proportions of infections due to subtypes B and E over time; and to generate data on DNA sequences of the C2-V3 region of the env genes. METHODS: HIV-1 subtyping was conducted by PEIA and HMA on blood specimens obtained from 97 injecting drug users (IDU) infected with HIV between 1988 and 1993. Genetic sequencing was performed on 84 specimens. RESULTS: Both laboratory methods were highly sensitive and specific for the determination of HIV-1 subtypes B and E. The two tests were complementary; samples which could not be typed by HMA were correctly typed by PEIA and vice versa. While subtype B accounted for 80.4% (78 out of 97) of infections overall, the proportion of new infections due to subtype E increased from 2.6% (one out of 38) in 1988-1989 to 25.6% (11 out of 43) in 1990-1991, and to 43.8% (seven out of 16) in 1992-1993 (chi 2 for linear trend, P < 0.001). CONCLUSIONS: HMA and PEIA are practical, sensitive and specific laboratory methods for the determination of HIV-1 subtypes in Thailand, and may be useful in other geographic areas to define the molecular epidemiology of the global HIV-1 pandemic. Data suggest that the proportion subtype E infections have increased among Bangkok IDU from 1988 through 1993.

The evolving molecular epidemiology of HIV-1 envelope subtypes in injecting drug users in Bangkok, Thailand: implications for HIV vaccine trials.

OBJECTIVE: To genetically characterize HIV-1 strains in injecting drug users (IDU) in Bangkok, Thailand in 1994, and compare these with strains found earlier in Thai IDU; such information is essential for HIV-1 vaccine development and evaluation. METHODS: Peripheral blood mononuclear cells were collected from 84 IDU attending 14 drug treatment clinics in Bangkok in 1994. DNA was amplified using a nested polymerase chain reaction (PCR) procedure and sequenced directly (without cloning) from the PCR products. The V3 and flanking regions (345 nucleotides) of the env gene were analyzed using a neighbor-joining tree. RESULTS: Only one (1%) strain was a typical subtype B virus, 69 (82%) were genetically distinct subtype B' viruses (Thai B), and 14 (17%) were subtype E strains (Thai A). Persons with recently acquired infection were more likely to have subtype E viruses (P < 0.001) than those in our 1991 survey, who were more likely to have subtype B' viruses. Pairwise intra-subtype differences within subtypes E and B' were 5.3 and 4.3%, respectively, compared with 3.4 and 3.5% among strains collected in 1991 in Thailand. CONCLUSION: The genetic diversity within subtypes B' and E in Thailand and the proportion of new infections due to subtype E viruses among Bangkok IDU are increasing significantly. These data highlight the importance of monitoring the molecular epidemiology of HIV-1 in populations being considered for HIV-1 vaccine trials.

HIV/AIDS-related behavior change among injecting drug users in different national settings.

OBJECTIVES: To identify factors associated with effective AIDS behavior change among injecting drug users (IDU) in different national settings. DESIGN: Cross-sectional surveys of IDU, with determination of HIV status. Trends in city HIV seroprevalence among IDU also used to validate effectiveness of behavior change. SETTING AND PARTICIPANTS: Subjects recruited from drug-use treatment programs and outreach efforts in Bangkok, Thailand (n = 601), Glasgow, Scotland (n = 919), New York City, USA (n = 2539), and Rio de Janeiro, Brazil (n = 466). RESULTS: Evidence for the effectiveness of self-reported risk reduction was available for all cities. Univariate followed by multiple logistic regression analyses were used to identify factors associated with self-reported AIDS behavior change. Separate analyses were conducted for each city. Talking about AIDS with drug-using friends was significantly associated with behavior change in all four cities. Talking with sex partners about AIDS, educational level, knowing that someone can be HIV-infected and still look healthy, and having been tested previously for HIV were each significantly associated with behavior change in three of the four cities. CONCLUSIONS: Despite the substantial differences in these national settings, there were common factors associated with effective risk reduction. In particular, risk reduction appears to occur through social processes rather than through individual attitude change. HIV prevention programs need to explicitly incorporate social processes into their work.

Viral load differences in early infection with two HIV-1 subtypes.

OBJECTIVES: Information on early HIV-1 infection has come primarily from studies of persons infected with subtype B in North America and Europe; much less is known about other subtypes. The purpose of the present study was to compare the virologic and immunologic parameters following seroconversion among recently-infected persons infected with either of two different HIV-1 subtypes. METHOD: A prospective cohort study was carried out at methadone treatment clinics administered by the Bangkok Metropolitan Administration, Thailand. A total of 130 HIV-1-infected seroconverters (103 with HIV-1 subtype E and 27 with subtype B) were included in the study. The main outcome measures were serial HIV-1 RNA viral load, natural killer cell percentage, CD4 and CD8 lymphocyte counts since seroconversion. RESULTS: The demographic and behavioral characteristics of persons with either subtype were similar. Median RNA viral levels at the earliest time within 3 months of seroconversion were more than three times higher for persons infected with subtype E than subtype B (63 100 versus 18 050 copies/ml, P = 0.001). However, this difference decreased over time such that viral loads were similar at 12, 18, and 24 months following seroconversion. The CD4 and CD8 lymphocyte counts were similar in infections with either subtype during the entire period up to 24 months post-seroconversion. CONCLUSIONS: Higher viral loads associated with subtype E may result from inter-subtype biological differences; however, the epidemiological dynamics of transmission in Bangkok may have also contributed to this phenomenon.

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 testing and sexual behavior among intravenous drug users in Bangkok, Thailand.

The relationships between previous HIV counseling and testing and sexual behavior were examined among injecting drug users in Bangkok. Six hundred one i.v. drug users (IVDUs) were recruited from drug treatment programs in November of 1989. A standardized interview on AIDS risk behavior was administered and a blood sample was collected for HIV testing of the 601 people. Fifty-six percent reported that they had not been previously tested (NPT), 15% had previously tested positive (PT+), and 29% had previously tested negative (PT-). Previous testing was associated with higher levels of safer sex and contraception with primary partners: 56% of the PT+ people with regular partners reported using condoms at least some of the time with that partner, compared with 28% of the PT- and only 20% of the NPT people. Similarly, 89% of the PT+ and 72% of the PT- people, compared with 59% of the NPT people, reported practicing some form of contraception with regular partners. The results strongly support the utility of HIV counseling and testing as a method of reducing heterosexual and perinatal HIV transmission among IVDUs in Bangkok.

A comparison of full-length glycoprotein 120 from incident HIV type 1 subtype E and B infections in Bangkok injecting drug users with prototype E and B strains that are components of a candidate vaccine.

Complete gp120 sequence information was obtained from eight persons with incident HIV-1 infections (four subtype E and four subtype B) who were part of a prospective injecting drug user (IDU) cohort in Bangkok, Thailand, during 1996-1998. The incident subtype E strains were similar to the prototype subtype E strain CM244 isolated in 1992 in northern Thailand. The incident subtype B strains displayed divergence, in both overall genetic distance and other significant gp120 characteristics, from the prototype North American subtype B strain HIV-MN. Recombinant gp120s derived from CM244 and HIV-MN strains are components of a vaccine that is undergoing phase III efficacy testing, begun in March 1999, among Bangkok area IDUs. The information presented here will be important in the evaluation of any breakthrough HIV-1 infections occurring among vaccinees during the vaccine trial and in ongoing vaccine development efforts in Thailand.

AIDSVAX (MN) in Bangkok injecting drug users: a report on safety and immunogenicity, including macrophage-tropic virus neutralization.

A randomized, double-blind, placebo-controlled phase I/II study of AIDSVAX (MN) was conducted among injecting drug users in Bangkok, Thailand. Four doses of vaccine (300 microg of MN-rgp120 in alum) or placebo (alum) were given at study entry and at 1, 6, and 12 months. The objectives of the study were to evaluate (1) the feasibility of conducting vaccine trials in this population; (2) the safety of this candidate AIDS vaccine; and (3) the immunogenicity of this vaccine. Thirty-three volunteers (22 vaccine and 11 placebo recipients) were recruited. None were lost to follow-up during the 18-month study. Mild reactogenicity was noted, which was similar in both vaccine and placebo recipients. The vaccine induced anti-HIV-1 antibody in all vaccine recipients. Maximal titers of binding antibodies of MN-rgp120 and the V3 domain of MN-rgp120 were induced after the third (6 month) dose while maximal neutralizing antibodies followed the fourth (12 month) dose. The vaccine-induced antibodies from several volunteers were capable of neutralizing macrophage-tropic, subtype B viruses (301660 and JRCSF) detected in a PBMC-based assay. Binding and neutralizing antibodies declined about 10-fold in the 6 months after the last boost. Two vaccinees became infected during the trial, both with subtype E viruses. A phase III efficacy trial, using a bivalent gp120 vaccine containing antigens from a subtype B virus (MN) and a subtype E virus (A244), was initiated in March 1999 in injecting drug users in Bangkok.

Evaluation of a sensitive/less-sensitive testing algorithm using the 3A11-LS assay for detecting recent HIV seroconversion among individuals with HIV-1 subtype B or E infection in Thailand.

The development of a serologic algorithm to determine recent HIV seroconversion, using sensitive/less-sensitive testing strategies, has generated widespread interest in applying this approach to estimate HIV-1 incidence in various populations around the world. To evaluate this approach in non-B subtypes, longitudinal specimens (n = 522) collected from 90 incident infections among injecting drug users in Bangkok (subtype B infection, n = 18; subtype E infection, n = 72) were tested by the 3A11-LS assay. Standardized optical density (SOD) was calculated, using median values, and the window period between seroconversion as determined by sensitive and less sensitive tests was estimated by a maximum-likelihood model described previously. Our results show that the mean window period of the 3A11-LS assay was 155 days (95% CI, 128-189 days) for subtype B but was 270 days (95% CI, 187-349 days) for subtype E specimens from Thailand. About 4% of individuals with incident subtype E infections remained below the threshold (SOD of 0.75), even 2 years after seroconversion. Among the patients with clinical AIDS and declining antibodies, none of the 7 individuals with subtype B, but 10 (8.7%) of 115 with subtype E infections, were misclassified as recent infections. Lowering the cutoff to an SOD of 0.45 for subtype E specimens resulted in a mean window period of 185 days (95% CI, 154-211 days), with all individuals seroconverting, and reduced the number of subtype E-infected patients with AIDS who were misclassified as having recent infection to 2.6%. Our results demonstrate that the 3A11-LS assay has different performance characteristics in detecting recent infections among individuals infected with subtypes B or E. Determining appropriate cutoffs and mean window periods for other HIV-1 subtypes will be necessary before this approach can be reliably implemented in settings where non-B subtypes are common.

Genetic characterization of incident HIV type 1 subtype E and B strains from a prospective cohort of injecting drug users in Bangkok, Thailand.

We obtained specimens from 128 HIV-1 seroconverters identified from 1995 through 1998 in a prospective cohort study of 1,209 HIV-negative injecting drug users (IDUs) in Bangkok, Thailand. Epidemiologic data indicated that parenteral transmission accounted for nearly all infections. HIV-1 DNA from the C2-V4 env region was sequenced, and phylogenetic analyses determined that 102 (79.7%) of the specimens were subtype E and 26 (20.3%) subtype B strains. All subtype B strains clustered with strains often referred to in previous studies as Thai B or B'. The interstrain nucleotide distance (C2-V4) within subtype E strains was low (mean, 6.8%), and pairwise comparisons with a prototype subtype E strain, CM244, showed limited divergence (mean, 5.6%). The subtype B stains showed greater interstrain divergence (mean, 9.2%) and were significantly divergent from the prototype B strain HIV-MN (mean, 13.0%; p < 0.0001). The subtype E strains had significantly lower mean V3 loop charge than did subtype B strains (p = 0.017) and, on the basis of analysis of amino acid sequences, were predicted to be predominantly (91%) non-syncytium-inducing (NSI), chemokine coreceptor CCR5-using (CCR5+) viruses. The subtype B strains had a higher mean V3 loop charge, and a smaller proportion (23%) were predicted to be NSI/CCR5+ viruses. This study demonstrates that most incident HIV1 infections among Bangkok IDUs are due to subtype E viruses, with a narrow spectrum of genetic diversity. The characterization of incident HIV-1 strains from 1995 to 1998 will provide important baseline information for comparison with any breakthrough infections that occur among IDUs in Bangkok who are participating in an HIV-1 vaccine efficacy trial initiated in 1999.

Risk behaviours and comprehension among intravenous drug users volunteered for HIV vaccine trial.

Out of 91 volunteers enrolled for the HIV vaccine trial, only 33 volunteers were eligible for vaccination. Of 33 volunteers recruited, 59 per cent of them had incomes of more than 5,000 Baht/ month. The median duration of drug addicts was 15 years (range 1-26 years) and 42 per cent never used condoms during sexual intercourse. As far as consent comprehension was concerned, all of them understood.

PIP: With HIV seroprevalence rates of 35-40%, Thai intravenous drug users are an obvious target group for anti-HIV vaccine trials. The Ministry of Public Health of Thailand recently approved clinical trials of the Genentech MN rgp 120/HIV-1 candidate vaccine among recovering intravenous drug users enrolled in a methadone treatment center in Bangkok. To evaluate safety and immunogenicity factors and assemble a relatively low-risk group, 91 potential volunteers from this center were screened (history, physical examination, and blood and urine analysis). Only 33 passed all of the screening procedures; the major causes of ineligibility were HIV seropositivity (14 cases) and impaired liver function test (10 cases). The 33 eligibles had a median duration of drug addiction of 15 years. The majority had a secondary education or above and a monthly income exceeding 5000 Baht (US$200). Never-use of condoms was acknowledged by 14 of the eligible volunteers, but all 33 denied relationships with commercial sex workers. Among those selected for the trial, 23 believed a successful vaccine against AIDS is likely and 30 thought the vaccine they received was effective; however, 12 were concerned the vaccine would enhance disease progression. After 12 months of counseling and participation in the vaccine trial, nine volunteers were drug and methadone-free. Overall, these findings indicate that intravenous drug users can successfully participate in vaccine trials if there is adequate pre-screening.

A controlled trial of methadone maintenance in a population of intravenous drug users in Bangkok: implications for prevention of HIV.

This study represents the first controlled trial of methadone maintenance and 45-day methadone detoxification in Thailand. We randomly assigned 240 male heroin addicts with at least six prior detoxification treatment episodes to 45-day detoxification or to methadone maintenance treatment conditions. We found that methadone maintenance clients were more likely to complete 45 days of treatment (p less than .00001), were less likely to have used heroin during treatment (p less than .0002), and were less likely to have used heroin on the 45th day of treatment (p less than .000007). These findings are consistent with the results of other studies in the United States, and we conclude that methadone maintenance could be a significant adjunct to AIDS prevention efforts for intravenous drug users in Thailand.

AIDS beliefs and behaviors among intravenous drug users in Bangkok.

Prompted by an explosive epidemic of HIV-1 in early 1988 among Thai IVDUs under treatment for heroin use, a series of focus group discussions were conducted at six Bangkok detoxification clinics. In developing qualitative information on knowledge of and attitudes toward AIDS, and on drug use and sexual behavior, our objectives were to identify intervention measures, develop culturally-appropriate educational material, strengthen counseling, and sharpen the focus of needed quantitative research. An abundant store of diverse anecdotal responses and reactions emerged. We discuss the reliability and the policy and research implications of these findings.

AIDS risk reduction and reduced HIV seroconversion among injection drug users in Bangkok.

Human immunodeficiency virus (HIV) seroconversion was studied in a group of 173 injection drug users in Bangkok, Thailand, who had been previously tested for HIV and were interviewed and retested in the fall of 1989. Ten percent of the group had seroconverted. Two factors protected against HIV seroconversion: having stopped sharing injection equipment in response to the acquired immunodeficiency syndrome (AIDS) and having a regular sexual partner. The association between self-reported deliberate risk reduction and reduced HIV seroconversion among persons continuing to inject illicit drugs indicates that injection drug users can change their behavior in response to AIDS and will accurately report on the behavior change, and that the changes can protect against HIV infection.