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.