AN OUTBREAK OF TYPE-A BOTULISM ASSOCIATED WITH A COMMERCIAL CHEESE SAUCE

Background: Although botulism is rare, recognition of a possible case of this illness represents a public health emergency. To prevent more cases, prompt investigation must be done to determine whether illness is linked to a commercial product or restaurant, Botulism can masquera de as other illnesses, and seemingly unlikely foods can harbor botulin um toxin. Objective: To confirm the diagnosis and determine the cause and extent of an outbreak of botulism associated with food served at a delicatessen. Design: Retrospective cohort study of patrons of the de licatessen; laboratory analysis of food, serum samples, and stool samp les; and traceback of implicated food. Setting: Community in Georgia. Participants: Patrons of the delicatessen. Main Outcome Measures: Botu linum toxin in food, serum, or stool and Clostridium botulinum in food and stools. Results: 8 of 52 patrons (15%) met the case definition fo r botulism. In 4 of the 8 patrons, an illness other than botulism was initially diagnosed. Five of the 8 were hospitalized, and 1 died. Stoo l cultures from 4 patrons yielded type A C. botulinum, and two serum s amples contained botulinum toxin. All ill persons ate food from the de licatessen on 1 October 1993. Of the 22 persons who ate at the delicat essen that day, all 8 ill persons but none of the 14 well persons ate a potato stuffed with meat and cheese sauce. An open can of cheese sau ce contained type A botulinum toxin and yielded C. botulinum on cultur e. Cheese sauce experimentally inoculated with C. botulinum spores bec ame toxic after 8 days at a temperature of 22 degrees C (room temperat ure). Conclusions: A commercial, canned cheese caused a botulism outbr eak. This product readily becomes toxic when contaminated by C. botuli num spores and left at room temperature. Mild botulism caused by unusu al vehicles may be misdiagnosed. Botulism should be included in the di fferential diagnosis of persons with signs or symptoms of acute crania l nerve dysfunction.