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The treatment of tuberculosis in refugees living in camps along the Thai-Kampuchean border has remained a controversial issue since the beginning of the Khmer relief operation in 1979. During the 1984-85 dry season, war-related disruptions forced the evacuation of the 240 000 residents of 21 camps into evacuation sites in Thailand. Seven tuberculosis treatment programmes, using a fully supervised, daily protocol of isoniazid(H), rifampicin(R), pyrazinamide(Z) and streptomycin(S) 3 HRZS/HR, (6 months for pulmonary and 9 months for extrapulmonary tuberculosis), were able to continue operation, with acceptably low rates of default from therapy. During the 18 month period beginning in July 1984, 984 patients were started on treatment: 755 completed a full course while 86 defaulted. The programme design and organisation are described.

SUMMARY The mycobacteriology laboratory provides the information necessary to diagnose mycobacteriosis and to suggest proper patient management. When the definite diagnosis of disease due to M. tuberculosis is made on the basis of the laboratory result, contact follow-up studies should continue and the patient may be considered infectious if the bacilli were isolated from the sputum. A report of another Mycobacterium species suggests that a contact follow-up is not necessary, that the patient need not be isolated, and that a therapeutic regimen should be based on the results of drug-susceptibility tests with the isolate. Techniques of molecular biology are being used in the laboratory to provide the necessary information quickly for patient management. BACTEC has been accepted into most clinical laboratories to speed reporting of results. Other methods such as genetic and immunologic probes are under development. New DNA probes have been marketed by GenProbe for the identification of cultures of M. tuberculosis, M. avium, and M. intracellular. HPLC and GLC have been used for the identification of cultures based on unique mycolic acid patterns of the species. Immunologic probes may eventually be the most specific and sensitive, but additional development is necessary. Mycobacteriophage typing of M. tuberculosis isolates has been developed as a tool to aid in epidemiologic studies. These and other technologies are essential in the support of programs for the elimination of tuberculosis.

Excerpt To the editor: As former medical coordinator (1984-85) of the United Nations Border Relief Operation on the Thai-Cambodian border, I read Soffer and Wilde's recent article (1) on medicine i...

To determine risk factors for HIV-1 infection in young men in northern Thailand.At enrollment into a prospective study, data were collected from a self-administered questionnaire and serologic testing on a cohort of 1115 young men selected by lottery for conscription.The overall HIV-1 infection rate was 6.9%; however, the rate was 15.3% among the 387 (34.7%) men who had been living in the upper north subregion of Thailand compared with 2.5% for the remaining 728 men (P0.001). A history of sex with female prostitutes was reported by 74.7% of men and increased frequency of this type of sex was highly associated with HIV-1 infection and a history of sexually transmitted disease (STD) symptoms (chi 2 for trend, P0.001). In stratified and multivariate analyses, however, history of STD symptoms, reported by 42.5% of the cohort, was most strongly associated with HIV-1 infection. Only 42.8% of men who reported sex with prostitutes had used condoms more than half the time.Young men in the general population in northern Thailand are at high risk for HIV-1 infection via sex with female prostitutes; STD are highly associated with HIV-1 infection. Increasing condom use and controlling STD should be immediate goals of HIV control programs.This study sought to determine risk factors for HIV-1 infection in young men in northern Thailand. This cohort of 1115 young men were selected by lottery for conscription and at enrollment into this prospective study, data were collected from a self-administered questionnaire and serologic testing. The overall HIV-1 infection rate was 6.9%; however, the rate was 15.3% among the 387 (34.7%) men who had been living in the upper north subregion of Thailand compared with 2.5% for the remaining 728 men (p 0.001). A history of sex with female prostitutes was reported by 74.7% of men and increased frequency of this type of sex was highly associated with HIV-1 infection and a history of sexually transmitted disease (STD) symptoms (chi square for trend, p 0.001). In stratified and multivariate analyses, however, history of STD symptoms, reported by 42.5% of the cohort, was most strongly associated with HIV-1 infection. Only 42.8% of men who reported sex with prostitutes had used condoms more than half the time. Young men in the general populations in northern Thailand are at high risk for HIV-2 infection via sex with female prostitutes; STDs are highly associated with HIV-2 infection. Increasing condom use and controlling STD should be immediate goals of HIV control programs.

The role of humoral immune response in HIV-1 subtype E mother-to-child transmission in Thailand was identified through investigation of sequential sera/plasma of 123 mothers infected with HIV-1 subtype E obtained at delivery and postpartum. Antibody-mediated neutralization of primary and T-cell line-adapted (TCLA) subtypes B and E HIV-1 isolates were examined as well as the antibody binding titers to HIV-1 env domains which included monomeric gp120 the CD4/gp120 binding sites (BS) V3 loop and gp41. Among the methods employed in the analysis were: V3 and gp41 peptide assays gp120 binding and CD4/GP120 binding site inhibition assays heteroduplex mobility assays neutralization assays and albumin determination. Results showed a good correlation between the paired levels of placental transfer antibodies in the babies and mothers at delivery (R2 = 0.7 for V3 peptide) while no correlation was found between maternal anti HIV-1 antibodies at delivery and vertical transmission of HIV-1 subtype E. The existence of a trend of low antibody-mediated cross-neutralization of a heterologous subtype B TCLA strain among Thai transmitting mothers was also revealed. This study confirmed findings in previous investigations of a significant difference in antibody levels (anti-HIV-1 antibodies) at delivery and at 6 months postpartum. The increase in HIV-1-specific antibody titers in infected mothers from delivery to 6 months postpartum was only partially explained by hemodilution as other factors are likely to affect postnatal humoral immunity.

The objectives were 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. 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. 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). 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. (authors)

To describe beliefs about remaining HIV-seronegative in injecting drug users in two high-seroprevalence cities, and to consider implications of these beliefs for ongoing risk reduction efforts and for HIV vaccine efficacy trials.Cross-sectional survey with open- and closed-ended questions.58 HIV-seronegative injecting drug users participating in HIV vaccine preparation cohort studies in New York City, New York, U.S.A., and Bangkok, Thailand.Large majorities of subjects in Bangkok (90%) and in New York (89%) believed their "own efforts" to practice safer injection methods and safer sex were very important in avoiding HIV infection. More Bangkok subjects (30%) believed that they would "probably" become infected with HIV in the future than New York subjects (4%). Three percent of Bangkok subjects and 70% of New York subjects believed "having an immune system strong enough to avoid becoming infected with HIV despite exposure to the virus" was very important in avoiding HIV infection. This belief in New York subjects was associated with having previously engaged in high-risk behaviors (i.e., sharing injection equipment, unprotected sex, or both) with partners known to be HIV-seropositive.Risk reduction programming for high-HIV-seroprevalence populations and within HIV vaccine trials should address not only specific HIV risk behaviors, but also the complex belief systems about avoiding HIV infection that develop within such groups. The person's "own efforts/self-efficacy" appears to be central in the psychology of risk reduction. Members of some high-risk populations may overestimate greatly the frequency of any possible natural immunity to becoming infected with HIV. Prevention programs for these populations will need to address explicitly the probabilistic nature of HIV transmission.Both New York City and Bangkok have experienced rapid, large-scale HIV epidemics among their IV drug using populations. The authors surveyed 58 HIV-seronegative IV drug users (IVDUs) participating in HIV vaccine preparation cohort studies in the two cities to gain insight into their beliefs about remaining HIV-seronegative. The 28 IVDUs in New York City and 30 IVDUs in Bangkok were recruited from ongoing cohort studies of HIV incidence among IVDUs in these cities. The New York cohort subjects were 76% male, 30% White, 27% Black, 43% Latino, and of median age 42 years. The majority had injected both heroin and cocaine. The Bangkok cohort subjects were 94% male, 100% Thai, of mean age 32 years, and almost all had injected heroin only. 89% of the subjects in New York City and 90% in Bangkok believed that their own efforts to practice safer injection methods and safer sex were very important in avoiding HIV infection. However, 4% of New York subjects and 30% of Bangkok subjects thought that they would probably become infected with HIV in the future. 70% of New York subjects and 3% of Bangkok subjects believed that having an immune system strong enough to avoid becoming infected with HIV despite exposure was very important in avoiding HIV infection. This latter belief among New York subjects was associated with having previously engaged in high-risk behaviors with partners known to be HIV-seropositive. Risk reduction programming for such populations and within HIV vaccine trials must take into account the prevailing belief systems about avoiding HIV infection.

To determine the incidence of and risk factors for HIV-1 infection among married women in northern Thailand the authors enrolled 779 seronegative women from family planning clinics and postpartum ward in Chiang Rai Thailand from 1998 through 1999. Women were tested for HIV antibodies at 6 and 12 months after enrollment. They received HIV prevention counseling at enrollment and at each follow-up visit. Counseling covered partner communication partner HIV testing and condom use by steady partners. Effects of counseling were measured using standardized questionnaires. Follow-up rates were 94% at 6 months and 92% at 12 months. Only 1 woman seroconverted during the follow-up period yielding an overall HIV incidence of 0.14/100 person-years. After receiving counseling women reported significantly increased communication with husbands concerning HIV risk HIV testing and condom use during the first 6 months after enrollment; communication remained high for 6-12 months. Women reported a modest increase in HIV testing and consistent condom use by husbands. The risk for HIV transmission to women in steady relationships is low in northern Thailand. Although HIV prevention counseling promoted communication its effects on HIV preventive behaviors were limited. (authors)

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 CRFO I―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.