Methamphetamine users in northern Thailand: changing demographics and risks for HIV and STD among treatment-seeking substance abusers.

Our objective was to determine sociodemographic, sexual and drug-use-related risk factors among methamphetamine (MA) users presenting for drug treatment in northern Thailand. Patients admitted for drug detoxification for MA and other drugs were studied cross-sectionally for risk factors associated with substance abuse and blood-borne and sexually transmitted pathogens. In all, 1865 (200 women) patients treated for MA, opiate, and mixed substance abuse between 1 February 1999 and 31 January 2000 completed all study procedures. Among 1865 participants, 750 (40.2%) were admitted for MA detoxification and 1115 (59.8%) for opiate (heroin, opium, or both) treatment. MA users were significantly younger, better educated, more likely to be Thai than highland ethnic minorities, and had significantly different sexual risks and sexually transmitted disease rates, including lower syphilis seropositivity and higher chlamydial prevalence, than persons admitted for opiate or mixed drug treatment. For those who reported MA use only, use by injection was rare and HIV infections significantly less common than among all other drug users. Thailand is undergoing an epidemic of MA use. These young users are a strikingly different population from opiate/heroin users in northern Thailand. MA users had higher rates of chlamydia infection than opiate users, reflecting their young age, and HIV rates in this population were lower than injecting drug users, but still elevated. MA use is a serious public health problem in Thailand and both improved prevention and treatment methodologies are urgently needed.

HIV incidence and risk behaviours after voluntary HIV counselling and testing (VCT) among adults aged 19-35 years living in peri-urban communities around Chiang Mai city in northern Thailand, 1999.

The Thai government began HIV voluntary counselling and testing (VCT) in all provinces in 1992. We evaluated HIV incidence after participants utilized VCT and its effect on risk behaviours among northern Thai adults aged 19-35 years. A total of 924 men and 1,327 women volunteered to participate in the study. Subjects were counseled, interviewed (socio-demographic, HIV risk behaviour, and HIV testing history), and tested for HIV infection at baseline and at 6 months follow-up. All participants were provided group pre-test counselling; HIV test results were provided in individual confidential post-test counselling. Overall, 329 of 391 men and 621 of 669 women who reported a prior HIV test before participating in our study reported negative results at the previous test. Of these, nine men and 13 women tested positive at baseline, giving incidence rates of 1.04 and 0.69 per 100 person years (PY), respectively. Recent risk behaviour was rare; as a result, the effects of VCT on risk behaviours among the study participants could not be determined. The HIV incidence after VCT among this study population is substantial. Studies to investigate factors associated with HIV incidence among VCT clients could provide insights for more effective HIV prevention.

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

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

High rates of transmission of subtype E human immunodeficiency virus type 1 among heterosexual couples in Northern Thailand: role of sexually transmitted diseases and immune compromise.

The heterosexual transmission of subtype E human immunodeficiency virus type 1 (HIV-1) infection was evaluated in 467 couples in Thailand in whom the man was HIV-1 positive and the woman had no risk factors for HIV other than sex with her infected partner. At baseline, 216 (46.3%) of the 467 women were positive for HIV-1; prevalence of HIV among women was 52.2% when their male partners had CD4+ lymphocyte counts of <200 cells/microL, 45.9% in women whose partners had counts of 200-499 micro/L, and 39.2% in women whose partners had counts of >/=500/microL. Women were twice as likely to be HIV positive if their partners had a history of a sexually transmitted disease (STD); however, their HIV prevalence was 29% among couples who had no STD history. It appears that female partners of men infected with subtype E HIV-1 are at high risk of infection even when the man's CD4+ cell count is relatively high. A high rate of STDs may contribute significantly to this risk [corrected].

Risk factors for HIV-1 transmission from HIV-seropositive male blood donors to their regular female partners in northern Thailand.

OBJECTIVE: To describe risks for HIV transmission from male blood donors to their regular female sex partners in Chiang Mai, Thailand. DESIGN: Cross-sectional study. METHODS: From March 1992 through September 1995, 405 HIV-seropositive male blood donors (index cases) and their regular female partners were enrolled in the study. Women with risk factors for HIV infection other than sexual contact with the index male were excluded. Couples were interviewed and examined; specimens were collected for laboratory analysis. RESULTS: Overall, 46% of the 405 women enrolled were HIV-positive. Ninety-eight per cent of male index cases had a history of sex with a female prostitute; 1.5% reported always using condoms with their regular partner. History of sexually transmitted disease (STD) and swollen inguinal lymph nodes in the female partner were associated with an increased risk of HIV infection in the female. History in the female of genital herpes [odds ratio (OR), 3.46; 95% confidence interval (CI), 1.50-8.78], gonorrhea or chlamydia infection (OR, 2.71; 95% CI, 1.39-5.53), and stable relationship of longer than 24 months (OR, 2.28; 95% CI, 1.02-5.09) were associated with an increased risk of HIV infection in the female. Consistent condom use in the past 2 years (OR, 0.10; 95% CI, 0.01-0.79) was associated with a decreased risk of HIV infection in the female. CONCLUSIONS: Married women in northern Thailand who appear otherwise to be at low risk for HIV infection may be exposed to this virus by their husbands. High rates of sex with commercial sex workers among men and low use of condoms within stable relationships may be important factors promoting the transmission of HIV in married couples. Programs to increase the regular use of condoms among married couples could be an important public health intervention to prevent transmission of HIV and other types of STD in northern Thailand.

PIP: The risk factors for HIV transmission from infected male blood donors to their regular female sex partners were investigated in a cross-sectional study conducted in Chiang Mai, Thailand, in 1992-95. During the 3.5-year study period, 405 couples were recruited. 98% of male blood donors reported a history of sex with female prostitutes. Only 28 men (7%) were aware of their seropositivity prior to notification by the blood bank, and just 1.5% always used condoms with their regular sex partner. 187 (46%) of the 405 female sex partners--none of whom had HIV risk factors other than sexual contact with their husbands--were HIV-positive at baseline. In the multivariate analysis, three variables were associated with a significantly increased risk of HIV in female partners: history of genital herpes (odds ratio (OR), 3.46; 95% confidence interval (CI), 1.50-8.78), history of gonorrhea or chlamydia (OR, 2.71; 95% CI, 1.39-5.53), and a stable relationship of at least 2 years' duration (OR, 2.28; 95% CI, 1.02-5.09); consistent condom use in the past 2 years was significantly associated with a decreased risk of HIV (OR, 0.10; 95% CI, 0.01-0.79). Medroxyprogesterone acetate injection and oral contraceptive use were not associated with HIV risk. These findings confirm a high risk of HIV transmission through monogamous sexual relationships in Thailand. Recommended are campaigns to increase regular condom use among married couples.

Sequences and phylogenetic analysis of the nef gene from Thai subjects harboring subtype E HIV-1.

PIP: It has been demonstrated that nef-defective SIV can cause attenuated disease in rhesus monkeys and that animals immunized with a similar construct can be protected when challenged with wild-type, pathogenic SIV. This finding has sparked interest in the nef gene of HIV-1. It remains unclear, however, whether nef serves an analogous role in human HIV-1 infection; Deacon et al. have reported an association of deletions in the nef gene with an attenuated disease course in humans, although other work does not support a strict correlation between the structure or function of nef and rates of disease progression. The nef gene product has been shown to influence the infectivity and pathogenicity of HIV-1. nef may also have a role in the immune response to HIV-1. The current database of nef sequences is derived almost exclusively from subtype B viruses. The authors therefore sought to develop a database of nef sequences from subjects infected with HIV-1 subtype E. Whole-blood samples were collected from 103 male commercial sex workers in Chiang Mai, Thailand. 17 tested positive for infection with HIV-1, 16 of whom were infected with subtype E by gp120 characterization. Intersubject variation in subtype E nef genes at the nucleotide level ranged from 2.1-7.8%. Thai subtype E nef sequences are more tightly clustered than subtype B nef sequences, analogous to what is seen in env. The authors note that their subtype E nef sequences do not share the genotypic polymorphism in the area of residues 10-30 noted with subtype B nef. These data confirm the need to develop a set of subtype E-specific reagents.^ieng

Maternal behaviour and socio-economic influences on the bacterial content of infant weaning foods in rural northern Thailand.

The bacterial contamination of infant weaning foods was examined in the context of a longitudinal study of lactation and infant growth, the Chiang Mai Lactation Study. Sixty-two mother-infant pairs were selected by random sampling from a rural area outside the city of Chiang Mai and studied for 48 hours in their homes on six occasions over the first year of life. Data on food hygiene practices and maternal factors were related to the total bacterial count per gram and coliform content of weaning foods. Bottle feeding, premastication, and mashing were significantly related to an increased bacterial content of weaning foods, while boiling foods to make soups, preparing in and feeding from a banana leaf, and using boiled water to prepare foods all reduced their bacterial content. Storage also increased the bacterial contamination in foods and foods were more highly contaminated in the rainy season. Maternal age and education were also related to some feeding practices. By promoting the feeding of traditional, but less contaminated weaning foods, an intervention is put forward which would aim to reduce weaning food contamination and thereby reduce incidence of diarrhoea in this area of Northern Thailand.

Life-spans of human T-cell responses to determinants from the circumsporozoite proteins of Plasmodium falciparum and Plasmodium vivax.

The longevity of specific human memory T-cell responses is largely unknown. However, a knowledge of the duration of memory is important for understanding immunity to an organism and for planning vaccine intervention. To address this, we have examined T-cell memory to malaria by determining T-cell responses by subjects recently exposed to peptides spanning the circumsporozoite (CS) proteins of two species of malaria-causing organisms, Plasmodium falciparum and Plasmodium vivax. Responses to vivax CS peptides by exposed Thai subjects were more frequent than responses by nonexposed individuals, permitting identification of determinants seen by vivax-induced responses. At the population level, there appears to be life-long memory, as the time since individuals were exposed did not diminish responsiveness to these determinants. In contrast, falciparum-exposed subjects were largely indistinguishable from nonexposed controls in responsiveness to falciparum CS determinants. However, a single peptide (F16: DNEKLRKPKHKKLKQPGDGN) was recognized significantly more frequently by P. falciparum-exposed than nonexposed Thai subjects. T cells responsive to this peptide were CD450+ and produced gamma-interferon. In contrast to the response to the vivax determinants and the other falciparum determinants, responsiveness to F16 was undetectable or minimal 2 years after exposure. Our data provide the average life-spans of certain malaria-specific T cells and are consistent with, but do not prove, the hypothesis that antigenic persistence (in the form of P. vivax hypnozoites) correlates with persistence of human T-cell memory.

Comparison of IgM, IgG and IgA responses to M.leprae specific antigens in leprosy.

Antibodies of IgM, IgG and IgA classes against M.leprae specific antigens (PGL-I, ND-O-BSA, and NT-O-BSA) were determined in the sera of 80 leprosy patients (28 untreated, 34 treated lepromatous and 18 tuberculoid), 25 tuberculosis patients and 33 normal individuals of Northern Thailand. No strong distinction in reactivity could be found between the three antigens. The IgM antibody assay yielded more positive results than assays for IgG and IgA. It was found that the positivity rates of IgM antibodies to all three antigens were highest in untreated lepromatous leprosy (82%). In tuberculoid leprosy, the positivity rates of IgM, IgG and IgA to the antigens were more variable, ranging from 22 to 50 percent. Patients with tuberculosis and normal individuals did not produce IgM antibodies against the antigens. The results suggested that the determination of IgM against the three antigens is a more sensitive and specific test for active leprosy than those of IgG and IgA. The relationship between the duration of treatment and IgM antibody levels in lepromatous leprosy (LL) was studied. Untreated LL patients had significantly higher IgM and IgA antibody levels than treated patients. There was no difference in IgG antibody levels between the two groups, and the levels of both groups were higher than normal controls. Serial determination of IgM antibodies in 7 LL patients revealed that treatment was strongly associated with progressive decrease in IgM antibody levels against all three antigens.

The bacterial content of infant weaning foods and water in rural northern Thailand.

Samples of weaning food and supplementary water were collected for analysis of bacterial content from among a random sample of 65 infants under the age of 1 year living in a rural area of northern Thailand. Using geometric means, mean total bacterial count of infant's drinking water was 351 organisms/ml (95 per cent CIs 170-770), and the most probable number (MPN) of faecal coliforms/ml was 47 (95 per cent CIs 19-78). Mean total bacterial count of weaning foods was 38,000 (95 per cent CIs 25,000-59,000) organisms/g with 10 per cent recording counts greater than 1,000,000 organisms/g. Bacterial counts were similar to those reported in weaning food and water in other developing countries, and were above internationally recommended 'safe' levels. The bacterial count of water was not affected by boiling, due to poor cleaning and frequent re-use of utensils. Weaning foods were contaminated during preparation, in part through premastication and also via mode of cleaning of utensils.