Feasibility of northern Thai factory workers as participants in HIV vaccine trials

To determine the feasibility of establishing a cohort of HIV-1 seronegative factory workers for potential HIV vaccine trials, and other HIV preventive interventions, we enroled and followed 499 male and female industrial workers in Lamphun Province, northern Thailand. A baseline demographic and HIV seroprevalence survey was conducted by a mobile team at worker's housing units in Lamphun Province in 1994. Follow-up HIV and syphilis incidence rates were measured 6 months later. The study was voluntary, anonymous, and included HIV pre- and post-test counseling, HIV and syphilis serology, and a self-administered fact sheet. A total of 106 men and 393 women were recruited. The median age was 22 years, and the mean 23.4 years. Educational levels were moderate; 41.9% had some secondary school and 23.6% had completed secondary school. HIV prevalence was 2.4% overall but differed by sex; among men it was 7/106, 6.6%, among women 5/393, 1.3%, OR = 5.49 (95% CI = 1.52, 20.39). Low educational levels were associated with HIV infection, OR = 7.2 (95% CI = 2.2, 23.4). Syphilis prevalence was 3.8%. Follow-up at 6 months was successful for 420/499 subjects, 84.2%, and varied by sex: 73/106 men, 68.9%, returned while 347/393 women, 88.3%, did so, RR = 1.21 (95% CI = 1.07, 1.37). There were 5 incident HIV-1 infections, a rate of 2.1/100 person years. The HIV seroconversion rate differed by sex, but not significantly; it was 4.1/100 person years for men and 1.5/100 person years for women. This population is largely young, female, and at considerable HIV risk. If follow-up could be improved, factory workers in northern Thailand could be an appropriate population in which to mount HIV preventive efficacy studies, including vaccine trials.

Measuring HIV-1 incidence in northern Thailand: prospective cohort results and estimates based on early diagnostic tests

Measuring the incidence of the human immunodeficiency virus (HIV) is of vital importance but can be difficult and costly. We compared HIV-1 incidence measured directly from prospective cohort studies with rates derived from a method using the prevalence of HIV-1 antibody-negative, p24-antigen-positive individuals. Male and female commercial sex workers (CSWs) were enrolled and followed in separate cohort studies in northern Thailand between 1989 and 1994, and HIV incidence was measured by prospective follow-up of individuals seronegative at baseline. In 1991-1992 cross-sectional serosurveys were done among male and female CSWs in the same region; all HIV-1 antibody-negative subjects in these surveys were tested for p24 antigenemia. HIV incidence was estimated using the prevalence of p24 antigen and a model based on the mean duration of p24 antigenemia before HIV antibody detection. The cohort studies showed high initial incidence rates-23.8/100 person-years (PY) among female CSWs and 11.9/100 PY among male CSWs-but poor compliance with prospective follow-up. Subjects lost to follow-up appeared to be at greater risk of HIV seroconversion than those retained. The p24 antigen method estimate among female CSWs, 25.4%/year, was quite similar to the initial incidence rate found in the cohort. The estimate by the p24 antigen method was higher, 19.9%/year, among male CSWs than that measured prospectively. In populations with high rates of HIV transmission and in whom long-term follow-up is incomplete, estimates of incidence using p24 antigen prevalence among antibody-negative subjects can give useful and economical estimates of HIV incidence and allow for estimates of whether the incidence rates are similar in subjects successfully followed and those lost to follow-up.

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.

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

BACKGROUND AND OBJECTIVES

Self-treatment for sexually transmitted diseases (STD) is common, but little studied, in Thailand, and its influence on human immunodeficiency virus (HIV) infection is unknown.

GOALS

To assess STD self-treatment and self-prophylaxis behaviors as well as HIV risks and serostatus among northern Thai men.

STUDY DESIGN

Cross-sectional report from a cohort of military conscripts (N = 869). HIV and STD seroprevalence and reported risk behaviors, including STD history and antibiotic self-treatment, were obtained. Associations between STDs and self-treatment or prophylaxis and HIV infection were analyzed using t-tests, odds ratios, and logistic regression.

RESULTS

The prevalence rate for HIV was 12.3%, and for syphilis it was 2.2%. Men who were seropositive for HIV were more likely to report having sex with commercial sex workers (OR 9.1), to have had an STD (OR 5.96) and to report inconsistent condom use with commercial sex workers (OR 3.13). Of 282 men reporting any STD, 65.2% treated themselves with antibiotics, and 8.5% used them before commercial sex. Among those who frequented commercial sex workers, 98.7% took preventive steps after sex by increasing urine output (69.2%), washing the genital area (28.9%), and using antibiotics (0.9%). Men reporting STD self-treatment were less likely to be HIV infected (OR 0.53; 95% CI 0.31, 0.93).

CONCLUSIONS

These men are attempting to prevent HIV and STDs. Self-treatment with antibiotics may lower HIV risks associated with bacterial STD in a high-prevalence population.

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

BACKGROUND AND OBJECTIVES

Prospective studies of incidental sexually transmitted diseases in developing countries rarely have been reported. As the human immunodeficiency virus epidemic widens, knowledge of the epidemiology of sexually transmitted diseases as co-factors for human immunodeficiency virus infection is viewed as vitally important.

GOAL

To determine epidemiologic risk factors for incidental sexually transmitted diseases in young men in northern Thailand.

STUDY DESIGN

A cohort of 2,417 men selected by lottery for military conscription was followed an average of 22 months, with epidemiologic risk factors and sexually transmitted disease histories assessed semiannually. Sexually transmitted diseases were determined by physician or symptom histories obtained by interview.

RESULTS

Sexually transmitted disease incidence was 17.04 per 100 person-years. Gonorrhea and chancroid were commonly reported, whereas incident syphilis was rare. Sexually transmitted disease incidence declined significantly in the 2-year period. Most sexually transmitted diseases were acquired through commercial sex patronage. However, among men who did not report visiting a brothel, there was a significant increase in sexually transmitted diseases among men reporting sex with a girlfriend. Other risk factors included inconsistent condom use, drug use, and low educational level. Frequent alcohol use was associated with incident sexually transmitted diseases in bivariate analysis, but drinking at the time of last brothel visit was not associated with increased sexually transmitted diseases.

CONCLUSIONS

Sexually transmitted disease control in Thailand is based on an integrated sexually transmitted disease clinic system. Many commercial sex workers are examined and treated routinely, but too infrequently to reduce sexually transmitted disease transmission between them and their male clients. Condom-use levels in commercial sex settings still may be too low to reduce sexually transmitted disease transmission. More consistent and effective sexually transmitted disease treatment of commercial sex workers and their clients and education of men on the effective and consistent use of condoms is required to reduce the risks of sexually transmitted disease transmission in this population.

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

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

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

OBJECTIVES

To determine the anticipated participation in a prophylactic AIDS vaccine trial and to identify perceived benefits and barriers to enrollment of HIV-seronegative volunteers at risk of HIV infection in northern Thailand.

DESIGN

A cross-sectional survey.

METHODS

Subjects interviewed in a cross-sectional survey included female commercial sex workers (n = 215), men attending sexually transmitted disease clinics (n = 219), conscripts in the Royal Thai Army (n = 1453), and men discharged from the army (n = 293) who had returned to civilian life. We determined AIDS vaccine knowledge and attitudes, perceived vulnerability to HIV infection, barriers and incentives to participate in a future vaccine trial and agreement to participate in a randomized trial.

RESULTS

Awareness of vaccines (88-97%) and AIDS vaccine development efforts (62-77%) were common and viewed to be a complement to behavior change (74-94%). Approximately 25% of subjects would definitely join a trial if asked, and an additional 38% would accept an AIDS vaccine if they were convinced it would be safe and effective. Important barriers to participation included concerns with discrimination (16-45%), short- (37-60%) and long-term (30-55%) vaccine side-effects, fear of disability and death (36-58%), and beliefs that partners would refuse to have sex (24-49%) after immunization. The principal inducement to join a trial was health insurance (62%).

CONCLUSION

Potential HIV vaccine trial participants have several fears of joining a vaccine study at this time. Information derived from Phase I/II trials is needed to address these concerns if enrollment in efficacy trials is to be successful in the near future.

Phenotypic and genotypic characteristics of human immunodeficiency virus type 1 from patients with AIDS in northern Thailand

Primary human immunodeficiency virus type 1 (HIV-1) isolates were obtained from 22 patients with AIDS from northern Thailand, where HIV-1 is transmitted primarily through the heterosexual route. Viral sequences were determined for the 22 patients with AIDS, and all were subtype E HIV-1 on the basis of sequence analysis of a region from the envelope protein gp120. Syncytium-inducing (SI) viruses were detected for 16 of 22 patients with AIDS by using MT-2 cells. Characteristics of amino acid sequences in V3 which have not been reported previously for subtype B SI HIV-1 were associated with the subtype E HIV-1 SI phenotype. The SI viruses from our study population contain predominantly a GPGR or GPGH motif at the tip of the V3 loop, in contrast to the previously described subtype E HIV-1 from Thailand which contained predominantly GPGQ. All the SI viruses lost a potential N-linked glycosylation site in V3 which is highly conserved among previously described subtype E HIV-1 isolates from asymptomatic patients from Thailand. HIV-1 envelope sequences including V3 from some patients with AIDS were significantly more divergent than viruses from asymptomatic patients in Thailand characterized 2 years ago or earlier. These results suggest that emergence of subtype E SI HIV-1 variants is associated with the development of AIDS, as it is for subtype B HIV-1. The divergence of subtype E HIV-1 in patients with AIDS as the disease progresses, and the divergence of subtype E HIV-1 in the infected population as the epidemic continues in Thailand, may have important implications for vaccine development.

The epidemiology of HIV and syphilis among male commercial sex workers in northern Thailand

OBJECTIVE

To examine the prevalence and incidence of HIV and syphilis, and risk behaviors for these infections, among 1,172 male commercial sex workers (CSW) followed prospectively from 1989 to 1994 in Chiang Mai, northern Thailand.

METHODS

Twice yearly visits were conducted by the Thai Ministry of Public Health at all cooperating gay bars and clubs (17 sites) in Chiang Mai City as part of a national HIV sentinel surveillance. Men and boys who agreed were followed prospectively. Sentinel visits included an interview, HIV pre-test counseling, HIV and syphilis serology, condom distribution, and referral for post-test counseling. Participation was voluntary, confidential, and individual HIV results were available only to participating subjects. A total of 219 CSW were seen at least twice, allowing for incidence estimates based on 100 person-years (PY).

RESULTS

Median age of male CSW was 20 years. Median time of work as a CSW was 4 months. Most men (57.6%) described themselves as heterosexual. Median number of clients was 2.5 per week, and reported condom use with clients was low: 42% reported inconsistent or no condom use, while 58% reported always using condoms. Reactive Venereal Disease Research Laboratory results were 7.6%, overall, but showed a declining trend. HIV prevalence was 1.4% in June 1989, 13.9% in June 1990, and 20.1% in December 1993, and showed a significant increasing trend. There were 27 incident HIV infections in 227.3 PY of observation, for an overall incidence during the 4.5-year period of 11.9 per 100 PY (95% confidence interval, 7.42-16.38).

CONCLUSION

Male CSW in northern Thailand are at high risk for HIV despite current prevention efforts. The majority are heterosexual, which may be an important epidemiologic link in the spread of HIV between male CSW users and heterosexual women in Thailand.

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

OBJECTIVES

To assess the risks for HIV infection and sexually transmitted diseases (STD) among young northern Thai men who have sex with men (MSM), and to examine the possible role of male same-sex behavior in the northern Thai HIV/AIDS epidemic.

METHODS

Two cohorts of northern Thai military conscripts and one cohort of recently discharged conscripts, a total of 2047 men, were studied. Data were collected by interview on behavioral risk factors, and sera were examined for syphilis and HIV-1 antibodies. Univariate and multiple logistic regression analyses were used to determine risk factors associated with HIV and STD, and to assess the frequency and patterns of same-sex behaviors among these men.

RESULTS

Of 2047 men, 134 (6.5%) reported one or more male lifetime sex partners. Of these MSM, 130 (97.0%) also had female partners, and four (3.0%) had exclusively male partners. Compared with men who reported only female sex partners, MSM had a higher number of lifetime sex partners, a higher mean number of female sex partners, more female and male commercial sex worker (CSW) partners, and were more likely to be married. MSM were significantly more likely than exclusively heterosexual men to report having had any STD [odds ratio (OR), 2.72], gonorrhea (OR, 2.05), syphilis (OR, 3.17), non-gonococcal urethritis (OR, 4.54) and penile discharges (OR, 6.24). They were at borderline increased risk for HIV infection [OR, 1.51; 95% confidence interval (CI), 0.95-2.41]. Men with more than one lifetime male sex partner compared with those with only one partner were significantly more likely to be HIV-infected (OR, 2.81; 95% CI, 1.09-7.19).

CONCLUSIONS

Northern Thai MSM are a high-risk population for STD, including HIV. Reported same-sex behavior in this population appears to vary considerably with data collection techniques. HIV and STD prevention strategies aimed at changing unsafe sexual practices may need to be targeted to the general population of young Thai men.

Epidemiology / vaccine efficacy trials. "HIV Incidence in Adults in Northern Thailand"

According to an abstract submitted by the authors to the X International Conference on AIDS, held August 7-12, 1994, in Yokohama, Japan, "

OBJECTIVE

To measure the HIV-1 incidence, follow-up rates and high risk behaviors in cohorts of seronegative adults in northern Thailand.

METHODS

We screened cohorts of female commercial sex workers (CSWs), male STD clinic patients, Royal Thai Army (RTA) conscripts, and discharged RTA conscripts at baseline and q3 to 6 months for HIV infection by ELISA and WB and did interviews for high risk behavior, medical history, and STD cultures.

RESULTS

Of 1068 CSWs, 409 (38.3%) were HIV positive, and 396 HIV negative were enrolled in the study; follow-up at 6 months was 70.7% and 19 seroconverted, for an incidence of 12.8/100 person years. Of 1031 male STD patients, 164 (15.9%) were HIV positive, and 264 HIV negative (30.4%) were enrolled; follow-up at 6 months was 91.9% and 6 seroconverted, for an incidence of 4.92/100 person years. Of 969 RTA conscripts, 12.4% were HIV positive at baseline and 90% were followed at 6 months; 3 of 778 seroconverted, for an incidence of 0.87/100 person years. (Previous RTA cohorts have had an incidence of 3.4%/year). Among 380 men discharged from RTA, follow-up at 9 months was 81.8% and the incidence was 5.2/100 person years. Sample sizes required to show an HIV vaccine efficacy of 60%, with a power-.90, alpha-.05 varies from CSUs 644, STD patients 1456 to ex-RTA-1306.

CONCLUSIONS

Several populations in northern Thailand appear to have sufficiently high HIV-1 incidence and adequate follow-up for HIV vaccine efficacy trials and other preventive intervention trials.

Unilateral acute idiopathic maculopathy

This is a report of nine patients who experienced sudden, severe, unilateral central vision loss following a flulike illness. Each patient had an exudative detachment of the macula. All patients experienced a spontaneous resolution of the acute macular manifestations with near-complete recovery of vision. A characteristic "bull's-eye" appearance in the macula persisted. The acute manifestations of the disorder did not recur in any of the patients during the period of follow-up. The constellation of findings was suggestive of an inflammatory disease of the retinal pigment epithelium, but a specific causative agent could not be identified. The acute clinical and angiographic features, the natural course, and the residual pigment epithelial derangement were not consistent with any previously described disorder.

Hypotony as a late complication of trabeculectomy

A young man with pigmentary glaucoma was treated successfully by trabeculectomy in one eye. Approximately 13 months later, relatively minor trauma produced hypotony. Despite repeated examinations, the causative factor, a minute wound leak in the filtering bleb, was not detected until the hypotony had been present for six months. During this time, vertical choroidal folds developed in the macular region, associated with a marked loss of central vision. Successful cryogenic repair of the leaking bleb and subsequent normalization of tension was achieved; however, pigmentary changes noted in the macula as induced by the choroidal folds persisted.