Epidemiologic aspects of shigellosis and other causes of dysentery in Thailand.

Nearly 20% of children seen in the outpatient department of Children's Hospital in Bangkok, Thailand, for diarrheal disease had bloody diarrhea. Shigella species and enteroinvasive Escherichia coli--isolated from 13% and 2% of children with diarrhea, respectively--were the most frequent causes of bloody diarrhea. Campylobacter species and nontyphoidal Salmonella species were also isolated frequently but were much less often associated with bloody diarrhea. Shigella species were rarely isolated from patients who did not have diarrhea, while Campylobacter and Salmonella species were isolated frequently from well children. None of the species isolated always caused bloody diarrhea. Studies on infection with Campylobacter suggest that natural immunity may prevent bloody diarrhea and in fact may eventually prevent all disease due to this organism. Studies of endemic Shigella flexneri and epidemic Shigella dysenteriae 1 in Thailand have shown that immunity may also explain an age-related decrease in rates of S. flexneri infection but not in rates of S. dysenteriae 1 isolation.