Comprehensive field investigation of a large botulism outbreak, Saudi Arabia, 2024.

Background: Botulism is an uncommon and possibly lethal disease caused by botulinum neurotoxins, produced by Clostridium botulinum, Clostridium butyricum, and Clostridium baratii. Food-borne botulism typically results from consuming homemade canned, preserved, or fermented food. This paper presents the first documented occurrence of a commercially prepared food-borne botulism outbreak in Saudi Arabia.

Methods: We used information from medical charts to describe the outbreak by time, place and affected persons. Individuals who consumed food from a specific restaurant chain in Riyadh within one week of its closure and experienced symptoms compatible with botulism were included. One hundred and two cases were interviewed. All clinical data, laboratory investigations, and information regarding antitoxin administration were obtained. We reviewed the results of samples collected from food handlers and the environment. The public health actions and the outbreak source investigations were detailed.

Results: A total of 50 cases have met the criteria for clinically confirmed botulism. Laboratory testing verified 10 (20 %) of the confirmed cases. Half of the cases were males with a mean age of 25.08 ( ± 6.42) and the other half were females with a mean age of 25.28 ( ± 9.38). Saudi nationals represented 90 % of cases. All cases reported eating from different branches of the same restaurant in Riyadh. The mean incubation period ranged from 4 to 101 h. Prevalent symptoms were dysphagia (80 %), dysarthria (78 %), peripheral muscle weakness (78 %), and diplopia (62 %). 96 % of cases received Antitoxin. Consumed food items included meat burgers (58 %), chicken burgers (22 %), fries (52 %), fries with meat (10 %), and sauces (100 %). BoNT types A and B were detected in one sample from a mayonnaise jar.

Conclusion: The study outlined an outbreak of food-borne botulism associated with commercially processed items. The early administration of antitoxins, high index of suspicion, and effective source control considerably reduced morbidity and mortality. It is uncommon for mayonnaise to cause botulism, so further testing is necessary to confirm this relationship. We recommend higher measures of monitoring and improving the food sector's preservation, storage, and quality control.