Salmonellosis and the food chain in Khon Kaen, northeastern Thailand.

Non-typhoidal salmonellosis is a major cause of food-borne illness in Thailand. Specific serotyping of Salmonellae, linked with certain foods, can be used to identify outbreaks, transmission, and for surveillance. We aimed to identify the chain of non-typhoidal Salmonella transmission from food to humans in five slums, two open markets, four supermarkets and an abattoir in the municipality of Khon Kaen. During three months representing the cool-dry, hot-dry, and rainy seasons of 2002, culture samples were collected from water, food, pork, and chicken. Stool cultures of food venders, and others in the same area, were performed. Serological typing was done by the WHO National Salmonella and Shigella Center in Thailand. Of the food, drinking water, and stool samples from food handlers and healthy persons, 18, 7, 11, and 5%, respectively, were positive for Salmonella. Nearly all (96-98%) of the fresh pork and chicken, both from the open markets and supermarkets, were positive for Salmonella. The major Salmonella serovars were S. Anatum, S. Rissen, S. Virchow, S. Enteritidis and S. Panama, similar throughout the food chain and to the other reports that year. To reduce the incidence of human salmonellosis, several preventative measures must be taken where animals are produced, slaughtered and processed, and at home and in eateries. Vulnerable groups, such as infants, the elderly and the immuno-compromised, should be made aware of their increased susceptibility to food-borne disease.