AN OUTBREAK OF SALMONELLA-HADAR ASSOCIATED WITH FOOD-CONSUMPTION AT ABUILDING SITE CANTEEN

A biphasic outbreak of gastroenteritis caused by Salmonella hadar affe cted canteen employees and workers at a construction site in central I taly in September 1994. There were 448 symptomatic cases, from 61 of w hom group C Salmonella was isolated. Six cases were canteen employees. Twenty-two other individuals were asymptomatic excreters. There were 10 secondary cases. Working as a food handler at the canteen constitut ed an increased risk of infection, independently of ingestion of the f ood (odds ratio: 62.1; 95% confidence interval (CI): 9.5-406.6). Havin g eaten at the canteen on the 19th and 20th September was identified a s risk factor for subjects symptomatic within 72 hours (relative risk (RR): 17.0, 95% CI: 2.3-124.3), and cooled meat salad was identified a s the vehicle of infection (RR: 36.6, 95% CI: 14.3-93.8). The use of p ortable toilets was another possible route of transmission of infectio n for all cases (RR: 1.3, 95% CI: 1.0-1.6). The index case was a cook who had symptoms five days before the peak of the outbreak. From 27 in dividuals both symptomatic and asymptomatic excreters group B, group D and not-typed Salmonellas were isolated. This study underlines the pr oblem of improper food handling in salmonellosis outbreaks and emphasi zes the role of several vehicles in the transmission of salmonellosis in a community.