A food-borne outbreak of streptococcal pharyngitis

Abstract

Background: Food-borne pharyngitis outbreaks causing substantial morbidity have been documented.

Objectives: To investigate an outbreak of food-borne Streptococcus beta hemolyticus group A pharyngitis among employees of a hitech company.

Methods: We received a report on an unusually high rate of morbidity among employees of a company in September 2003. The Tel Aviv District Health Office conducted an epidemiological investigation of the outbreak.

Results: Among the 278 people who attended a company party, 83 became ill. The overall attack rate was 29.8%. Information was available on 174 of 193 employees and family members who attended the party and worked in the Tel Aviv district. Forty-six of them became ill (attack rate 26.4%). The secondary attack rate was 3.8%. Most cases developed symptoms 24-48 hours following the event. Seven cases had throat cultures positive for Streptococcus beta hemolyticus group A. Three items were significantly associated with becoming sick: spring chicken (odds ratio 2.26, 95% confidence interval 1.11-4.63, P = 0.02), vegetable salad (OR 2.88 95% CI 1.40-5.94, P = 0.003) and corn (OR 7.73, 95% CI 3.18-18.80, P < 0.001). Eating corn remained significantly associated with pharyngitis after controlling for other food items consumed.

Conclusions: We describe the epidemiological investigation of a large food-borne outbreak of Streptococcus beta hemolyticus group A pharyngitis most probably transmitted by corn. No previous publication has implicated corn. Food handlers and the public should be aware that they can transmit diseases to others. Physicians should be aware that streptococcal pharyngitis could be a foodborne disease and that outbreaks in a non-confined setting may be easily missed.