Unexpectedly high HIV prevalence among female sex workers in Bangkok, Thailand in a respondent-driven sampling survey

The pattern of sex work in Thailand has shifted substantially over the last two decades from direct commercial establishments to indirect venues and non-venue-based settings. This respondent-driven sampling survey was conducted in Bangkok in 2007 among female sex workers (FSW) in non-venue-based settings to pilot a new approach to surveillance among this hidden population. Fifteen initial participants recruited 707 consenting participants who completed a behavioural questionnaire, and provided oral fluid for HIV testing, and urine for sexually transmitted infection (STI) testing. Overall HIV prevalence was 20.2% (95% confidence interval [CI] 16.3-24.7). Three-quarters of women were street-based (75.8%, 95% CI 69.9-81.1) who had an especially high HIV prevalence (22.7%, 95% CI 18.2-28.4); about 10 times higher than that found in routine sentinel surveillance among venue-based FSW (2.5%). STI prevalence (Chlamydia trachomatis and Neisseria gonorrhoeae) was 8.7% (95% CI 6.4-10.8) and 1.0% (95% CI 0.2-1.9), respectively. Lower price per sex act and a current STI infection were independently associated with HIV infection (P < 0.05). High HIV prevalence found among FSW participating in the survey, particularly non-venue-based FSW, identifies need for further prevention efforts. In addition, it identifies a higher-risk segment of FSW not reached through routine sentinel surveillance but accessible through this survey method.

Access to HIV testing for sex workers in Bangkok, Thailand: a high prevalence of HIV among street-based sex workers

We offered voluntary counseling and testing (VCT) for HIV and syphilis to women attending three public sexually transmitted infection (STI) clinics in Bangkok, Thailand from May 2004 to June 2006. The testing was performed at either one of three STI clinics in Bangkok or at mobile VCT in the same area as the outreach activity. Six-hundred eighty-four women were tested. The HIV prevalences among the street-based sex workers, brothel-based sex workers and other women in these areas not reporting sex work who tested in the clinics were 45.8% (38/83), 4.2% (10/236) and 9.9% (28/284), respectively. The prevalences of syphilis in these groups were 13.3%, 2.1%, and 2.6%, respectively. Street-based sex work and longer duration of sex work were independent risk factors for HIV in-fection (p < 0.001 and p = 0.02, respectively). HIV and syphilis prevalences were 21.0% and 3.7% among 81 street-based sex workers accepting mobile VCT, The street-based sex workers in Bangkok had substantially higher HIV and syphilis prevalences than other sex workers. Street-based sex workers should be sampled during routine surveillance to obtain systematic information on disease preva-lence and risk behaviors in this group.

Indicators for sexual HIV transmission risk among people in Thailand attending HIV care: the importance of positive prevention

BACKGROUND

Almost half of all new HIV infections in Thailand occur among low-risk partners of people infected with HIV, so it is important to include people infected with HIV in prevention efforts.

METHODS

Risk for HIV transmission was assessed among people with HIV attending routine care at the National Infectious Disease Institute in Thailand. Sexual risk behaviour, sexually transmitted infection (STI-syphilis, gonorrhoea, chlamydia, trichomoniasis and genital ulcers) prevalence and HIV disclosure status were assessed. Patients were provided with STI care, risk-reduction and HIV disclosure counselling.

RESULTS

Baseline data were assessed among 894 consecutive people with HIV (395 men and 499 women) from July 2005 to September 2006. Unprotected last sex with a partner of unknown or negative HIV status (unsafe sex) was common (33.2%) and more likely with casual, commercial or male-to-male sex partners than with steady heterosexual partners (p = 0.03). People receiving antiretroviral treatment were less likely to report unsafe sex (p<0.001). Overall, 10.7% of men and 7.2% of women had a STI (p = 0.08). More women than men had disclosed HIV status to their steady partners (82.5% vs 65.9%; p = 0.05).

CONCLUSION

Indicators for HIV transmission risk were common among people attending HIV care in Bangkok. Efforts need to be strengthened to reduce unsafe casual and commercial sex and to increase HIV disclosure from men to their partners. A strategy for STI screening and treatment for people with HIV in Thailand should be developed.

Factors contributing to treatment success among tuberculosis patients: a prospective cohort study in Bangkok

SETTING

Chest Clinic, Ministry of Public Health and health care centres, Bangkok Metropolitan Administration.

OBJECTIVE

To determine patient factors predicting successful tuberculosis (TB) treatment.

DESIGN

A prospective cohort was conducted during May 2004 to November 2005. Newly diagnosed TB patients aged > or = 15 years were recruited after giving informed consent. Three sets of questionnaires were used to collect data from the patients three times. Data were also gathered from treatment cards.

RESULTS

Of 1241 patients, 81.1% were successfully treated. Bivariate analysis indicated that patients' sex, education, occupation, level of knowledge about TB and adverse effects were associated with treatment success. Unconditional logistic regression analysis showed that females had a higher success rate than males (OR = 1.9, 95%CI 1.2-2.9). Patients with regular incomes had twice the likelihood of success of the unemployed (OR = 2.0, 95%CI 1.1-3.5). Patients with high knowledge levels were more likely to complete treatment (OR = 2.0, 95%CI 1.2-3.4), while those with adverse effects were less likely to adhere (OR = 0.6, 95%CI 0.4-0.9).

CONCLUSION

The current low treatment success rate may be partly due to inadequate knowledge about TB among patients. Improvements in health education and early detection and management of adverse effects should be prioritised by the National Tuberculosis Programme.

Restriction fragment length polymorphism study of nationwide samples of Mycobacterium tuberculosis in Thailand, 1997-1998

SETTING

During 1997-1998, a national anti-tuberculosis drug resistance survey was conducted in Thailand as a part of a global project.

OBJECTIVE

To evaluate the IS6110 hybridisation patterns and the level of clustering, which was expected to be low due to the short duration of the sample collection.

DESIGN

Eight hundred and twenty-eight bacterial isolates were available for fingerprinting by standard IS6110 hybridisation.

RESULTS

The restriction fragment length polymorphism patterns varied with geographic locations, ages of the patients, and resistance to rifampicin and streptomycin. The Beijing strain was more common among younger patients, and their prevalence appeared to decrease with the distance from Bangkok, while the opposite was true for the single-banded isolates. Excluding isolates containing five or less copies of IS6110, 26.4% were clustered. Clustering was more common among females. The clustered isolates were sometimes from different provinces and, if resistant to drugs, usually possessed different resistance profiles.

CONCLUSIONS

The results question the validity of inferring recent transmission from the clustering of IS6110 hybridisation patterns in some settings in Thailand. The level of recent transmission in a nationwide study in a country with a high incidence of tuberculosis should be evaluated with caution.

Integrated counseling and screening for tuberculosis and HIV among household contacts of tuberculosis patients in an endemic area of HIV infection: Chiang Rai, Thailand

SETTING

Combined hospital-based and home visit, Chiang Rai, Thailand.

OBJECTIVE

To describe the results of screening of tuberculosis (TB) and HIV infection among household contacts of TB patients in an area endemic for HIV.

DESIGN

Consecutive new smear-positive TB patients were interviewed and their household contacts were screened for TB including tuberculin skin test (TST), chest radiography, and sputum examination. Voluntary HIV testing and counseling was also performed.

RESULTS

Of 499 pulmonary TB index cases, 197 (39.5%) were HIV-positive; 1200 household contacts were screened for TB and 890 (74.2%) agreed to HIV testing. The prevalence of TST induration > or = 10 mm and active TB among household contacts of HIV-positive pulmonary TB cases were 46.2% (225/487) and 2.9% (14/490), and among household contacts of HIV-negative TB cases were 62.1% (438/705) and 4.4% (31/710), respectively. Higher HIV prevalence was found among contacts of HIV-positive TB patients than among household contacts of HIV-negative TB index cases (52/376, 13.8% vs. 13/514, 2.5%) (P < 0.001). Spouses of HIV-positive TB cases had the highest HIV prevalence (36/74, 48.6%). Among the household contacts who were HIV-positive, 9.5% (7/74) had active TB.

CONCLUSION

Integrated counseling and screening for TB and HIV should be provided for household contacts of TB patients in an HIV endemic area.

Resistance to anti-tuberculosis drugs among smear-positive cases in Thai prisons 2 years after the implementation of the DOTS strategy

SETTING

Three prisons in Bangkok and vicinity, Thailand.

OBJECTIVE

To examine the prevalence of drug-resistant tuberculosis among smear-positive cases in Thai prisons 2 years after the implementation of the DOTS strategy, and to identify factors associated with resistance to anti-tuberculosis drugs.

METHODS

In a cross-sectional study, 154 consecutive tuberculosis patients with at least one positive sputum smear and at least one positive sputum culture registered between 1 May and 31 October 2000 were enrolled. Drug susceptibility testing was performed by the Ministry of Public Health Tuberculosis Division. Patient characteristics were obtained by face-to-face interview.

RESULTS

Resistance to at least one drug was found in 50.6% of the subjects, including multidrug-resistant tuberculosis (MDR-TB) in 19.5%. The proportion of resistance to any anti-tuberculosis drug in prisons A, B and C was respectively 52.7%, 37.8% and 61.5%. The only factor significantly associated with resistance to at least one drug (P = 0.011) and MDR-TB (P < 0.001) was a history of previous tuberculosis treatment.

CONCLUSION

After 2 years of the DOTS strategy, resistance to anti-tuberculosis drugs, an indicator of the quality of tuberculosis treatment, was found to be high. The DOTS strategy currently used in Thai prisons should be reviewed, in order to reduce and prevent drug-resistant tuberculosis.

Tuberculosis preventative therapy as part of a care package for people living with HIV in a district of Thailand

We studied the risk factors for default in isoniazid preventative therapy (IPT) against tuberculosis in 412 people living with HIV (PLWH) in Mae Chan Hospital, Thailand. Default rates decreased from 57% in 1995 to 17% in 1999. Female sex, residence inside Mae Chan District, and registered in the PLWH group at enrollment of IPT were associated with lower default rates. The integration of IPT into the PLWH day care centre activities over the years might contribute to improvements.

Prevalence of drug-resistant tuberculosis in an HIV endemic area in northern Thailand

SETTING

Chiang Rai Province in Northern Thailand, where human immunodeficiency virus (HIV) infection has been prevalent since the 1990s.

OBJECTIVE

To observe the prevalence of drug-resistant tuberculosis (TB) and investigate the factors related to the level of drug resistance in an HIV endemic area.

DESIGN

Population-based surveillance study covering the whole province.

METHOD

Drug susceptibility testing was performed at the Thai Ministry of Public Health laboratory for all sputum smear-positive TB patients diagnosed in hospitals in Chiang Rai Province over a 25-month period in 1996-1998. Patient characteristics were obtained through interview by trained personnel. HIV testing was performed with informed consent.

RESULTS

Among the 1077 incident patients without previous history of treatment, the proportion of patients with resistance to isoniazid was 13.2%, 10.8% to rifampicin, 15.6% to streptomycin, and 5.8% to ethambutol. Multidrug resistance (MDR), i.e., resistance to at least both isoniazid and rifampicin, was observed in 6.3%. Factors associated with primary MDR-TB were HIV positivity (OR 2.2, 95%CI 1.3-3.9), age <50 years (OR 2.0), and treatment in the provincial hospital (OR 2.3), compared to patients treated in the community and private hospitals. Stratified analysis shows a significantly high prevalence of primary MDR-TB among HIV-positive patients treated in the provincial hospital against HIV-negative patients or HIV-positive patients in other hospitals.

CONCLUSION

The prevalence of primary MDR-TB in this area was high. It is necessary to strengthen TB control activities in order to reduce the burden of MDR-TB.

Costs and benefits of improving tuberculosis control: the case of Thailand

The study evaluates the economic costs and benefits of improving tuberculosis control interventions in Thailand. Provider costs are determined on the basis of marginal treatment costs for varying case numbers and estimates of the cost of required infrastructure changes. Indirect costs are calculated as income lost due to morbidity and premature mortality. An epidemiological model is used to calculate case numbers and mortality under current control conditions and a scenario of improved control. An improved control strategy initially leads to a higher number of detected cases. For longer projection periods, the epidemiological impact of curing a higher proportion of infectious sources results in lower case numbers than those expected without programme improvement. Model simulations show a reduction of total annual case numbers through improved control measures by an average 45% after a simulation period of 20 years. The corresponding societal savings in form of reduced indirect costs from the disease are U.S.$2.4 billion. Reductions in direct provider costs can be expected as a result of decreased numbers of detected cases for longer evaluation periods, as well as a lower proportion of multi-drug-resistant cases. The mean value of predicted savings is U.S.$8.3 million. Since this value is likely to be higher than the required investment in improved infrastructure, net savings can be expected. The result of an uncertainty analysis shows a wide range of potential additional costs or net savings with respect to direct provider costs. Indirect cost calculations show net savings for all parameter values.

Adherence to tuberculosis preventive therapy among HIV-infected persons in Chiang Rai, Thailand

OBJECTIVE

To determine the level of and reasons associated with adherence to tuberculosis preventive therapy among asymptomatic HIV-infected individuals in northern Thailand.

DESIGN

A prospective cohort study with a 9-month follow-up.

METHODS

A total of 412 HIV-infected persons were enrolled in a tuberculosis preventive therapy programme in a hospital. A 9-month isoniazid regimen was prescribed. Adherence was determined by pill count. Participants who missed a scheduled appointment for more than a month were interviewed. Five focus group discussion sessions were held among those who successfully completed the therapy.

RESULTS

Of the 412 participants, 69.4% (286) completed the 9-month regimen. The adherence rate, defined as the proportion of those who took more than 80% of pills, was 67.5% (n = 278). Sex, source of participants and history of physical symptoms were associated with adherence. A significant portion of defaults took place at the beginning of the therapy. Out-migration, denial of HIV status, and perceived side effects of isoniazid were frequently cited as reasons for non-adherence. For those adhering participants, the acceptance of personal HIV status, concern about children and family, and a good health provider relationship were important reasons motivating adherence. Several reminder systems were developed by the participants.

CONCLUSIONS

Although a isoniazid preventive therapy programme was shown to be feasible, further adjustments on the selection of participants, enrollment process, and follow-up system based on these findings are necessary to increase the adherence.

Rapid increase in HIV-related tuberculosis, Chiang Rai, Thailand, 1990-1994

OBJECTIVE

Chiang Rai, the northernmost province of Thailand, has experienced an explosive HIV epidemic since 1989. This study assessed the impact of HIV infection on tuberculosis (TB) in the area.

METHODS

We analyzed the incidence of reported TB in the province from 1982 through 1993 and TB registry data at Chiang Rai Hospital from 1985 through 1994.

RESULTS

Following a steady decline in reported TB from 1982 through 1991, the incidence of TB increased sharply after 1991. TB registry data from Chiang Rai Hospital, which began confidential HIV testing in October 1989, indicated a steady and rapid increase in the number and proportion of HIV-seropositive TB patients from four (1.5% of all TB patients) in 1990 to 207 (45.5%) in 1994 (P < 0.001). Compared with HIV-negative TB patients, HIV-positive TB patients were more likely to be men, aged 20-39 years and have extrapulmonary TB (P < 0.001). Treatment completion rates were similar. Twelve months after beginning TB treatment, HIV-positive TB patients had a mortality rate of 68.6% [95% confidence interval (Cl), 62.7-74.3] compared with 10.0% (95% Cl, 8.3-12.1%) in HIV-negative patients (P < 0.001).

CONCLUSION

Thailand and other Asian countries where HIV is spreading rapidly must promptly address the dual epidemic of TB and HIV in order to reduce preventable morbidity and mortality.

The effect of thalidomide on the pathogenesis of human immunodeficiency virus type 1 and M. tuberculosis infection

Tumor necrosis factor alpha (TNF-alpha), a cytokine produced during the host defense against infection, is associated with fevers, weakness, and progressive weight loss. Thalidomide inhibits the synthesis of TNF-alpha both in vitro and in vivo and may have clinical usefulness. We therefore initiated a pilot study of thalidomide treatment in patients with human immunodeficiency virus type 1 (HIV-1)-associated wasting with or without concomitant infection with tuberculosis. Thirty-nine patients were randomly allocated to treatment with either thalidomide or placebo in a double-blind manner for 21 days. Thirty-two patients completed the study. In patients with concomitant HIV-1 and tuberculosis infections, thalidomide therapy was associated with a reduction in both plasma TNF-alpha levels and HIV-1 levels. No significant reduction in either TNF-alpha or HIV- 1 levels was observed in patients with HIV-1 infection only. During the study period, patients receiving thalidomide treatment (n=16) showed a significant weight gain (mean +/- SEM: 6.5 +/- 1.2%; p<0.02) relative to placebo-treated patients (n=16). Patients with simultaneous HIV-1 and tuberculosis infections experienced a higher mean weight gain during thalidomide treatment than the group of patients with HIV-1 infection only. The results of this pilot study suggest that thalidomide may have a clinical role in enhancing weight gain and possibly reducing TNF-alpha and HIV-1 levels in patients with HIV-1 and concomitant mycobacterial infections.

Risk factors for HIV-1 seroconversion among young men in northern Thailand

OBJECTIVE

To identify behavioral and sociodemographic risk factors for incident human immunodeficiency virus-1 (HIV-1) infection among healthy young men in northern Thailand.

DESIGN

Men inducted into military service in northern Thailand in May and November 1991 were followed at 6-month intervals until discharge 2 years later. Trained nonmilitary interviewers identified risk factors for HIV-1 infection through interviews with the men.

SETTING

Thirteen military bases in northern Thailand.

PARTICIPANTS

A total of 1932 seronegative men, aged 19 to 23 years (average age, 21 years) at enrollment, conscripted into the Royal Thai Army and Air Force from six upper-northern Thai provinces.

MAIN OUTCOME MEASURES

Human immunodeficiency virus-1 seroincidence as determined through enzyme-linked immunosorbent assay and verified by Western blot, and univariate and multivariate analyses of risk factors related to HIV-1 incidence.

RESULTS

A total of 85 men seroconverted to HIV-1 over the period of observation, giving an incidence rate of 2.43 per 100 person-years. Factors strongly associated with HIV-1 seroconversion were frequency of visits to female commercial sex workers (CSWs), sex with men, and incident sexually transmitted diseases (STDs). High frequency of condom use showed a significant (P < .001) protective effect for HIV-1 incidence among men with a history of recent sex with female CSWs in univariate analysis, but a multivariate model demonstrated no difference in HIV-1 seroconversion rates by consistency of condom use. Multivariate analysis incorporating condom use showed that having sex with men (adjusted relative risk [RR], 2.59; 95% confidence interval [CI], 1.08 to 6.25), having sex with CSWs (adjusted RR ranged from 2.54 [95% CI, 1.81 to 3.58] to 2.74 [95% CI, 1.56 to 4.81]), and incident STDs (adjusted RR, 2.38 [95%, CI, 1.31 to 4.32]) to be predictors of incident HIV-1 infection. Substance use was not associated with HIV-1 seroconversion rates in multivariate analysis.

CONCLUSION

The HIV-1 incidence in this cohort of young men appears to be primarily attributable to having sex with female CSWs. Condom use provided some protection, although not in multivariate analysis; however, condom use has previously been shown likely to be useful in preventing HIV-1 transmission. Thus, programs to increase effective condom use in brothels are essential. Efforts to extend condom use to non-CSW partners are especially needed. More effective prevention and treatment of STDs may also be necessary to decrease HIV-1 infection in this population.

Thalidomide treatment reduces tumor necrosis factor alpha production and enhances weight gain in patients with pulmonary tuberculosis

BACKGROUND

The monocyte-derived cytokine, tumor necrosis factor alpha (TNF alpha), is essential for host immunity, but overproduction of this cytokine may have serious pathologic consequences. Excess TNF alpha produced in pulmonary tuberculosis may cause fevers, weakness, night sweats, necrosis, and progressive weight loss. Thalidomide (alpha-N-phthalimidoglutarimide) has recently been shown to suppress TNF alpha production by human monocytes in vitro and to reduce serum TNF alpha in leprosy patients. We have therefore conducted a two-part placebo-controlled pilot study of thalidomide in patients with active tuberculosis to determine its effects on clinical response, immune reactivity, TNF alpha levels, and weight.

MATERIALS AND METHODS

30 male patients with active tuberculosis, either human immunodeficiency virus type 1 positive (HIV-1+) or HIV-1-, received thalidomide or placebo for single or multiple 14 day cycles. Toxicity of the study drug, delayed type hypersensitivity (DTH), cytokine production, and weight gain were evaluated.

RESULTS

Thalidomide treatment was well tolerated, without serious adverse events. The drug did not adversely affect the DTH response to purified protein derivative (PPD), total leukocyte, or differential cell counts. TNF alpha production was significantly reduced during thalidomide treatment while interferon-gamma (IFN gamma) production was enhanced. Daily administration of thalidomide resulted in a significant enhancement of weight gain.

CONCLUSIONS

The results indicate that thalidomide is well tolerated by patients receiving anti-tuberculosis therapy. Thalidomide treatment reduces TNF alpha production both in vivo and in vitro and is associated with an accelerated weight gain during the study period.

HIV-1 seroconversion rates among female commercial sex workers, Chiang Mai, Thailand: a multi cross-sectional study

OBJECTIVES

To determine HIV seroconversion rates among female commercial sex workers (CSW) in Chiang Mai, Thailand.

DESIGN

A three-round multi cross-sectional study was used at approximately 3-month intervals.

METHODS

In December 1989, 38 brothels (60%) in Chiang Mai were randomly selected. All 518 female CSW in the brothels were interviewed about their sociodemographics, sexual practices, condom use, history of sexually transmitted diseases (STD) and other risk factors. Blood was tested for Venereal Disease Research Laboratory (VDRL)-reactivity and HIV-1 antibody. The same brothels, which were all still operating, were revisited in March and July 1990 and 431 and 320 CSW, respectively, were interviewed and blood-tested. Pelvic examination, cervical, urethral and rectal cultures for gonococcus were added to the study in March 1990, although rectal culture was dropped from the study in July 1990.

RESULTS

There were 5.2% [95% confidence interval (CI), 4.1-10.6] and 3.6% (95% CI, 1.5-5.4) per woman-month HIV seroconversion rates for the December-March and March-July periods, respectively. Of the CSW, 71.6-77.0% reported histories of at lest one STD. Condom-use rates among these CSW were reported to be 85.8-91.8%. High rates of positive cervical (11.2-12.3%) and urethral (8.8-11.4%) cultures for gonococcus were also found in the CSW.

CONCLUSIONS

The fact that high HIV seroconversion rates and high STD prevalence rates occur despite high rates of reported condom use suggests that more aggressive education programs are needed in Thailand.

HIV-1 infection among lower class commercial sex workers in Chiang Mai, Thailand

OBJECTIVE

To determine risk factors for HIV-1 infection in female commercial sex workers (CSW) in northern Thailand.

METHODS

A cross-sectional survey of female CSW from 11 sex establishments frequented by military conscripts that included an interview and serological testing for HIV-1.

RESULTS

The HIV-1 seroprevalence in 230 CSW was 65%; the rate was lower among CSW from Chiang Mai than from rural areas. Multivariate logistic regression analysis for HIV-1 included the following significant factors: non-urban location of the sex establishment, ethnic Thai lowlander, lower price, history of genital warts and dysuria. Condom use, number of partners and duration of employment were not significantly associated with HIV-1 prevalence after adjustment for other risk factors.

CONCLUSIONS

The high level of HIV-1 seroprevalence in this sample demonstrates the risk of transmission in lower cost commercial sex encounters in northern Thailand. Non-Thais (ethnic Hill tribes and Burmese) had lower HIV-1 prevalence than ethnic Thais. Type of establishment ('direct' brothel-based or 'indirect' establishments) was not predictive of HIV-1 seroprevalence. However, rural establishments were less vigilant in promoting condom use, suggesting the need for renewed efforts to enforce the Ministry of Public Health's '100% Condom Campaign' in commercial sex establishments.

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.

Risk factors for HIV infection among young adult men in northern Thailand

OBJECTIVE

To determine the sociodemographic and behavioral risk factors associated with human immunodeficiency virus (HIV) infection in two cohorts of young men selected for military service in northern Thailand.

DESIGN

Military conscripts were studied cross-sectionally after conscription in May 1991 and November 1991. Risk factors were assessed by interview with trained nonmilitary interviewers.

SETTING

Two military training bases in Chiang Mai, Thailand.

PARTICIPANTS

A total of 2417 young men aged 19 to 23 years (mean age, 21 years) conscripted by lottery into military service in the Royal Thai Army or Royal Thai Air Force from six provinces in northern Thailand.

MAIN OUTCOME MEASURES

Human immunodeficiency virus seroprevalence by enzyme-linked immunosorbent assay confirmed by Western blot and univariate and multivariate analyses of sociodemographic and behavioral risk factors associated with HIV seroprevalence.

RESULTS

Overall, 289 (12.0%) of 2417 men were HIV-seropositive at baseline. The strongest associations with being HIV positive were heterosexual activities. History of sex with a female commercial sex worker (CSW) was frequent (96.5% of men who were HIV-positive and 79.0% of men who were HIV-negative) and strongly associated with HIV infection on univariate and multivariate analyses (adjusted odds ratio, 1.60 to 2.07, depending on the frequency of CSW contact). Also, sexually transmitted diseases were common and associated with HIV infection in both univariate and multivariate analyses (adjusted odds ratio, 3.36). Sex with other males and injection drug use were uncommon and not associated with HIV infection. Condom use was reported in 61.5% of men at last sex with a CSW but was not shown to be protective of prevalent HIV infection.

CONCLUSION

The epidemic of HIV infection has spread widely among young men in northern Thailand, despite reported frequent and recent use of condoms during sex with female CSWs. Control of HIV infection in this population will probably require more regular and effective use of condoms, prevention and treatment of sexually transmitted diseases, and reduction in the frequency of CSW contact.

A cholera outbreak associated with eating uncooked pork in Thailand

In a village near Chiangmai, Thailand, during October 1987, there was an outbreak of cholera following a funeral in which 264 attendants were served food. The present article is a report of an epidemiological study performed to identify the source of infection and the mode of its transmission. All the attendants were screened for infection by bacteriological examination of their rectal swabs and were kept under diarrhoeal surveillance. Of them, 20 patients and 40 matched controls were interviewed about the details of their eating foods served at the funeral. Vibrio cholerae 01, Inaba, El Tor was detected from 24 persons (9.1%), 15 of whom suffered from mild diarrhoea and the rest 9 had inapparent infections. There was no death. Except one butcher whose rectal swab was positive for the same strain of V. cholerae, 3 other butchers and 4 women who had prepared food were free from the infection. Food remnants were not available for culture. The water used for cooking and the water from the cement well used for slaughter were negative for the organism. The only significant association (p less than .01, odds ratio = 15) was found between an attack of cholera and eating laebmoo--an uncooked pork preparation with Thai spices and chili. The transmission of cholera appeared to have occurred through eating the uncooked pork presumably due to its contamination with V. cholerae shed by the infected butcher. He was known to have earlier visits to Chiangmai where cholera epidemic was going on.

Several sporadic outbreaks of El Tor cholera in Sunpathong, Chiang Mai, September-October, 1987

From September through October 1987, a cholera outbreak involving 59 cases of biotype El Tor, serotype Inaba occurred in Sunpathong district, Chiang Mai. No cases died. Twenty-seven cases were males and 32 were females. The age ranged between 4 months and 85 years, with a median of 36 years. The outbreak affected 7 small communities, and showed different vehicles of infection. Six housewives and one girl were infected with cholera in the first localized outbreak. The transmission of infection appeared due to the consumption of packed food contaminated by an infected food handler. In the second localized outbreak, 6 young males acquired cholera after eating uncooked fish harvested from a canal contaminated with cholera organisms. Another outbreak of cholera with 24 culture-confirmed cases occurred among guests at a funeral held in one rural village. The source of infection was traced to uncooked pork contaminated from an infected butcher: Early detection of infected persons, rapid identification of possible vehicles of transmission, and prompt implementation of control measures effectively curtailed the extension of these outbreaks.