Frequency and risk of HIV infection among men attending a clinic for STD in Chiang Mai, Thailand.

A prospective study was conducted in the Chiang Mai Sexually Transmitted Diseases Clinic to determine the frequency of HIV seroconversion among men following high risk sexual contacts and to establish risk factors for HIV infection. HIV antibodies were detected in 26 out of 150 men on the initial recruitment with a seroprevalence rate of 21%. Among 124 initial HIV negative subjects; 100, 77, 68, and 55 subjects were followed for 2, 4, 12, and 24 weeks, respectively. One subject had HIV seroconversion documented with the rate of 1.0% (1/100, 95% confidence interval [CI] = 0.03-5.4%). Logistic regression analysis found significantly independent associations of HIV prevalence with prostitute visits at least once a month (OR = 3.6, 95% CI = 1.2-10.9), and with cigarette smoking (OR = 3.5, 95% CI = 1.2-10.5). Intensive health education should be elucidated to decrease the high rate of HIV infection among this population.

Outbreak of hepatitis A in a college traced to contaminated water reservoir in cafeteria.

A sharp but short outbreak of hepatitis A occurred in a college during September and October 1992. The epidemic pattern suggested a common source. The attack rate of clinically recognizable hepatitis A was 8% all cases were HAV IgM positive. Among 31 students with minor symptoms but without jaundice 8 (26%) were also HAV IgM positive, as were 8 (10%) of 77 totally asymptomatic students tested. A case control study of eating and drinking habits of the students showed no other significant differences other than that 45 of 56 cases and 18 of 34 controls interviewed had filled their water glasses by dipping them in a overflow water reservoir. This gives an odds ratio of 3.8. The reservoir was heavily contaminated with coliform bacteria and the residual chlorine was at lower than standard concentration, whereas other water resources were clean. It is suggested that the reservoir had been contaminated with hepatitis A virus by somebody with fecally contaminated hands a couple of weeks prior to the beginning of the outbreak.

A second outbreak of cholera in the home for mentally handicapped, Nonthaburi.

A second outbreak of cholera, due to the Ogawa strain, occurred in the home for Mentally Handicapped Children in Nonthaburi between July 29 and August 9, 1992. An outbreak of cholera due to the Inaba strain was reported in the same institution and season tin 1987. In 1992, the clinical attack rate was 8 per cent of 440 children; there were two deaths. Bath water was contaminated with Vibrio cholerae O1 E1 Tor Ogawa, the same strain as was isolated from the ill children. Chlorination of the water supply, obtained from an underground well, was insufficient. The water supply needs further investigation, and the sanitary conditions in the institutions should be improved.

Epidemic of fever of unknown origin in rural Thailand, caused by influenza A (H1N1) and dengue fever.

In the late summer (rainy season) of 1987, a sharp outbreak of fever of unknown origin (FUO) in rural southern Thailand was investigated by a field epidemiology team. In a random survey of households, 40 percent of the children and 20 percent of adults were reported to have had febrile illnesses within the last month. There was at least one death, possibly from Reye's syndrome. Testing 34 pairs of acute and convalescent sera showed significant HI antibody titer rises to influenza A (Taiwan/(H1N1) (9 cases) and dengue virus (12 cases). Testing 79 single sera with the antibody capture ELISA test for dengue, revealed that 23 percent had high titers in the IgM serum fraction suggesting recent infection. There were also six antibody titer rises to coxsackie B viruses, three from well controls. Dengue has previously been observed as a cause of FUO in rural areas in the tropics, but finding a combined epidemic of dengue and influenza was unexpected. With cooperative villagers, adequate personnel and laboratory support, especially the antigen capture ELISA test for dengue infections, it is feasible to successfully investigate disease outbreaks with serologic methods in remote villages.

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.