Foodborne Botulism: A Study of 57 Cases in Northwest Iran

Background: Foodborne botulism (FBB) is a rare paralyzing disease caused by ingestion of foods contaminated with botulinum neurotoxin (BoNT). It is still a health concern in many countries. This study aimed to investigate the epidemiology of FBB in West Azerbaijan Province, Iran. Methods: Botulism surveillance data of the Health Deputy of Urmia Medical Sciences University, northwestern Iran was used in this retrospective survey from 2010 to 2014. Demographics, clinical features, bioassay results, implicated foods and outcome were analyzed. Clinically, patients were classified to three groups (mild, moderate, and severe). Results: During the five years, 57 cases of FBB were identified involving 36 men (63.2%) and 21 women (37.8%). Mean age was 22.35±17.84 yr. Most events were sporadic (86%). Bioassay confirmed serotype A of BoNT in 19 patients (33.3%). The most implicated food was locally-made cheese (n=10). Average incubation period was 24.35±12.35 h. Clinically, mild, moderate and severe forms were observed in 68.4%, 19.3% and 12.3% of patients, respectively. All cases were hospitalized and treated with trivalent antitoxin. Mean hospital stay was 7.71±3.94 days Eight patients (14%) required mechanical ventilation and three of them deceased (5.3%). Median annual incidence rate of FBB was 0.37 cases per 100,000 population in this study. Conclusion: Comparing other part of the world, FBB has a medium incidence rate in our province. Unpasteurized dairy products are the main causative foods and BoNT/A is the most commonly recognized toxin type. Promoting correct preservation and appropriate cooking are recommended for preventing FBB.