HIV prevalence in upper socioeconomic level hospital patients, 1991-1993.

Five elite, private hospitals in Bangkok serving the upper socioeconomic stratum of Thai society were sampled for HIV prevalence among unlinked, anonymous specimens collected from general inpatients (sampled 11/1991 to 1/1992) and from women in labor (sampled 5/1992 to 4/1993). The HIV-1 antibody positivity rate by ELISA/Western blot was 0.45% (9 of 2,000) among all inpatients, and 0.1% (1 of 1,000) among pregnant women. The latter rate was appreciably lower than rates between 1 and 2% found in sentinel surveys among pregnant women in public hospitals during comparable time periods, suggesting the epidemic is more advanced in lower socioeconomic groups.

An outbreak of El Tor cholera in an institution for the mentally retarded in Nonthaburi, June-July 1987.

In June and July 1987, an outbreak of cholera caused by V.cholerae O1, biotype El Tor, serotype Inaba, occurred in an institution for the mentally retarded in Nonthaburi. Of the 447 retarded inmates, 74 were found to be infected and one died. Epidemiological investigation revealed that the inmates with severe mental retardation who ate food in their own sleeping-room were significantly (p less than 0.001) more likely to be infected than those taking food in the dining-room. We hypothesize that the liquid diet commonly served to the more severely mentally retarded may have increased the risk of infection by more rapid gastric emptying. The long average period of time for meal consumption among these individuals may have allowed the organisms to multiply to a level capable of causing disease. Contamination of food with cholera might have occurred during food handling in the kitchen or within the sleeping-room where overcrowded conditions and poor personal hygiene facilitated person-to-person spread of infection. Prompt implementation of control measures effectively terminated cholera transmission in the outbreak.

Epidemic leg ulcers in Thailand.

In 1981, two outbreaks of chronic leg ulcers occurred in central Thailand and affected thousands of persons. The lesions were characterized by granulomatous bases with erythematous edges and purulent slough. They were about 1 cm in diameter with irregular shapes. The ulcers lasted two weeks to one month. Ninety percent of the lesions were found on the lower extremities. The outbreak in Nakorn Pathom province occurred in fruit yards. Most of patients were gardeners and students. The outbreak in Ratchaburi province occurred on a sugar cane plantation. The age group of 5-19 years had the highest attack rate in all areas, and there was no significant difference between the attack rates in males and females. The peak incidence occurred in the rainy season with an abrupt decrease at the onset of the dry season. It is hypothesized that trauma precedes the occurrence of the leg ulcer and that a small fly may be a mechanical vector of the causative organism. The organism may be corynebacterium pyogenes, which is a pathogen of certain livestocks and is found in soil. Further studies are planned.