Brote de faringoamigdalitis de origen alimentario por estreptococo betahemolítico A

Background: Although infrequent, some authors have reported outbreaks of foodborne tonsillopharyngitis. On May 11, 2010 a series of cases of tonsillopharyngitis among those attending a fellowship meeting on 8 March was notified to the Epidemiological Surveillance Network in Andalusia (SVEA). The aim of this study is to epidemiologically characterise the outbreak. Methods: Descriptive analysis of reported cases and case - control exposure to the implicated food. The variables taken into account were age, sex, symptoms and start date. Sources of information used were the records of the SVEA and individual digital report (DIRAYA). Frequencies and attack rates were calculated, and a Bayesian analysis for the comparison of difference in proportions of disease was carried out for a 95% probability or credibility range (IP). Results: Among the 130 attendees at a communion 41 cases of tonsillopharyngitis (attack rate 31.5%) were detected, and in smears Group A Beta-Hemolytic Streptococcus was isolated. The most affected age group was the 25-44 year-olds, 16 (39,0%); 68.6% (24) female. The egg salad showed a probability greater than 80% P(Δ>0.10 and Δ>0.15) for a 95% IP of risk of disease after intake and a probability of having a lower risk of no disease. Conclusions: It was a Group A Beta-Hemolytic Streptococcal outbreak, the epidemiological evidence indicates exposure to common single source, hence the hypothesis of dietary origin, the implicated food was egg salad. Contributing factors could be cross-contamination after preparation favoured by the bad practice and the conditions of the place.