Food-borne botulism. A review of 13 outbreaks.

Thirteen outbreaks of food-borne botulism occurred between 1970 and 1984. Fifty patients were affected, with 30 of them requiring hospitalization. The number of patients per outbreak ranged from one to ten (mean, 3.8). All outbreaks were caused by home-prepared foods: nine by smoked ham, one by bacon, one by sausage, and one by mussels; contaminated food was not found in one outbreak. Bacteriologic study was performed in 11 outbreaks and type B toxin, the only found, was detected in eight of them. Generalized muscular weakness, visual disturbances, extreme dry mouth, and severe constipation were observed in all inpatients. Palpebral ptosis, dysphonia, urinary retention, postural hypotension, and respiratory impairment were also reported, but not in all inpatients. Identical, but less severe, manifestations were registered in the 20 ambulatory patients. Electromyographic study showed decreased motor action potential and posttetanic facilitation. Pulmonary function, studied in four inpatients, was decreased in three. All patients recovered fully. Management consisted of supportive measures, symptomatic treatment, and nursing care. Equine antitoxin was not administered and assisted ventilation was unnecessary.