A Food Illness Outbreak Caused by Salmonella muenster.

An outbreak of Salmonella food poisoning affected 12 persons attending a home dinner in Riyadh on January 10, 1980. The clinical manifestations were mild in 3 of the patients and severe in the other 9. The incubation period ranged between 14 and 32 h with an average of 18 h. The illness lasted 3-4 days. The clinical symptoms included diarrhea, abdominal colics, vomiting, fever (38-40 C), chills, headache, dizziness, inappetence and muscle and joint aches. Six of the patients required the care of a physician, but none of them required hospitalization. Epidemiological investigation of the outbreak revealed that the implicated food was roast beef. Nine persons who attended the same dinner, but did not eat roast beef, were not ill. The fresh roast beef, approximately 2 kg, was bought from a supermarket. It was cooked the night before the dinner, refrigerated for 24 h, warmed the next day and kept at ambient temperature in the kitchen for about 3 h before it was served. Bacteriological examination of the roast beef showed that Salmonella muenster was present in large numbers. Stool specimens of 11 of the patients were positive for S. muenster . Eight of them excreted the same Salmonella serotype up to 17 days after recovery from the illness; two other patients excreted this serotype up to 27 days after recovery.