Restaurant-associated Type A Botulism: Transmission by Potato Salad

In the period November 13-18, 1978, seven cases of type A botulism occurred in persons who had eaten in a restaurant in Colorado. The outbreak was recognized when two persons who had independently eaten at the restaurant were hospitalized with an illness compatible with botulism. Surveillance efforts identified five additional cases. Potato salad made at the restaurant and available for service during an 11-day period was epidemiologically incriminated as the vehicle of botulinal toxin transmission (p less than 0.00001). Laboratory studies showed that Clostridium botulinum spores on the surface of potatoes could survive baking in the manner used by the restaurant and that botulinal toxin could be produced in potatoes contaminated with C. botulinum spores.