Botulism is a severe, life-threatening disease caused by neurotoxins produced by Clostridium botulinum [1]. These neurotoxins, among the most potent natural poisons, can lead to sudden, non-febrile, symmetric descending flaccid paralysis, requiring immediate medical attention to prevent fatal outcomes [2]. Seven types of botulinum neurotoxins (A–G) exist, with types A, B, and E being most harmful to humans [3]. Foodborne botulism is the most common globally, resulting from the ingestion of food contaminated with botulinum neurotoxin [4]. The incubation period ranges from 12 to 36 hours but can vary [5]. Clostridium botulinum spores are ubiquitous in the environment and can contaminate food during processing if not adequately preserved [6]. Early diagnosis, rapid antitoxin administration, and mechanical ventilation are critical for treatment [7]. Continuous monitoring and strict food safety protocols are essential to prevent outbreaks.
We hypothesized that the food served by this restaurant was the source of this food poisoning outbreak. To test this hypothesis, a retrospective chart review study was designed
We used a retrospective chart review study using primary data. Suspected cases seeking medical care from all hospitals (MOH, non-MOH, and private) were interviewed by the Field of Epidemiology Training Program and the public health department of the General Directorate of Health Affairs in Riyadh. We developed a semi-structured questionnaire to collect demographic data, food consumption history, date and time of illness onset, presenting symptoms, hospital visit and admission, and prognosis. The Saudi Food and Drug Authority (SFDA) collected food samples for laboratory confirmation of BoNT. Also, we reviewed the medical files for all the cases including admitted cases to retrieve relevant data. Data collection continued until the outbreak was declared over.
Our study included 102 suspected cases of botulism, with 50 clinically confirmed and 10 laboratory confirmed. The other 52 suspected cases tested negative. All cases reported eating at different branches of the same restaurant. Of the confirmed cases, 50% were male, with a mean age of 25.18 years. Nationalities included 90% Saudi and 10% non-Saudi. Symptoms observed were blurred vision, dysphagia, dysarthria, diplopia, peripheral muscle weakness, dyspnea, nausea, diarrhea, vomiting, and headache. Incubation periods ranged from 4 to 101 hours, with 92% experiencing symptoms within 48 hours. Most cases ate on April 21, with symptom onset peaking on April 22. Antitoxin was administered to 98% of cases, with one patient experiencing a mild anaphylactic reaction. Consumed items included meat burgers (58%), chicken burgers (22%), fries (52%), fries with meat (10%), and sauces (100%).
Blood samples were taken from 96% of the cases. The Public Health Authority laboratory confirmed 14% of cases as positive for Clostridium botulinum. Laboratory confirmation of BoNT types in food items was managed by SFDA, the results confirmed BoNT type B in the mayonnaise and BoNT types A and B in the paper mayonnaise.
We Investigated the kitchen lab and one of the restaurants uncovered significant deficiencies in food safety measures. Improper storage practices were evident, including an overloaded refrigerator containing expired items and instances of mixed storage.
A fast-food chain in Riyadh, with about 25 outlets and a large online delivery business, was identified as the source of a botulism outbreak. Confirmed cases had consumed fried potato chips, salads, and hamburgers with a common seasoning. Investigation and lab tests revealed a jar of processed mayonnaise, used in the seasoning sauce, tested positive for toxin-producing C. botulinum. The jar originated from a local food manufacturing facility, prompting a nationwide recall of its products. The contamination appeared confined to this solitary jar, used at the central processing unit between April 18th and 20th, and no other contaminated items were found.
Following the initial notification on April 25, 2024, the Quartet Committee temporarily closed the implicated restaurant within three hours and collected food samples for testing. The SFDA conducted these tests, while the Ministry of Health issued a public statement to raise awareness. Specific public health measures included sending SMS messages to all registered healthcare personnel to raise clinical suspicion of botulism. Proactive phone calls were also made to individuals who had ordered meals online from the restaurant, inquiring about symptoms of botulism.
Our study outlined a substantial outbreak of foodborne botulism associated with commercially processed items. The early administration of antitoxins, high index of suspicion, and effective source control considerably reduced morbidity and mortality. We recommend higher measures of monitoring and improving the food sector's preservation, storage, and quality control.
Table 1: Demographic and hospital admission characteristics of foodborne botulism cases (n = 50), Saudi Arabia, 2024.
| Characteristics | Number of Cases | % of Cases | |
| Age | Mean | 25.18 | |
| ± Std Dev | 7.96 | ||
| Min-Max | 12-51 | ||
| Gender | Male | 25 | 50 |
| Female | 25 | 50 | |
| Age Group | 12-21 | 19 | 38 |
| 22-31 | 21 | 42 | |
| 32-41 | 8 | 16 | |
| 42-51 | 2 | 4 | |
| Nationality | Saudi | 45 | 90 |
| Non-Saudi | 5 | 10 | |
| Incubation period | 4 to 101 hrs | ||
| Hospital admission status | Ward | 10 | 20 |
| ICU | 5 | 10 | |
| Discharge | 34 | 68 | |
| Dead | 1 | 2 | |
Reference:
1. World Health Organization (WHO). Botulism [Internet]. 2023 [cited 2024 May 27]. Available from: https://www.who.int/news-room/fact-sheets/detail/botulism
2. Lonati D, Schicchi A, Crevani M, Buscaglia E, Scaravaggi G, Maida F, et al. Foodborne Botulism: Clinical Diagnosis and Medical Treatment. Toxins (Basel). 2020 Aug 7;12(8):509.
3. Rao AK, Sobel J, Chatham-Stephens K, Luquez C. Clinical Guidelines for Diagnosis and Treatment of Botulism, 2021. MMWR Recommendations and Reports. 2021 May 7;70(2):1–30.
4. Rasetti-Escargueil C, Lemichez E, Popoff MR. Public Health Risk Associated with Botulism as Foodborne Zoonoses. Toxins (Basel). 2019 Dec 30;12(1):17.
5. Centers for Disease Control and Prevention (CDC). Botulism: Clinical Description [Internet]. 2006 [cited 2024 May 27]. Available from: https://emergency.cdc.gov/agent/botulism/clinicians/clindesc.asp#:~:tex….
6. Dahlsten E, Lindström M, Korkeala H. Mechanisms of food processing and storage-related stress tolerance in Clostridium botulinum. Res Microbiol. 2015 May;166(4):344–52.
7. Păuna AM, Crăciun MD, Sîrbu A, Popescu R, Enciu BG, Chivu CD, et al. Botulism Cases in Romania—An Overview of 14-Year National Surveillance Data. Biomedicines. 2024 May 10;12(5):1058.