An outbreak of Salmonella hadar associated with food consumption at a building site canteen.

A biphasic outbreak of gastroenteritis caused by Salmonella hadar affected canteen employees and workers at a construction site in central Italy in September 1994. There were 448 symptomatic cases, from 61 of whom 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 constituted an increased risk of infection, independently of ingestion of the food (odds ratio: 62.1; 95% confidence interval (CI): 9.5-406.6). Having eaten at the canteen on the 19th and 20th September was identified as 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 as the vehicle of infection (RR: 36.6, 95% CI: 14.3-93.8). The use of portable toilets was another possible route of transmission of infection 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 individuals both symptomatic and asymptomatic excreters group B, group D and not-typed Salmonellas were isolated. This study underlines the problem of improper food handling in salmonellosis outbreaks and emphasizes the role of several vehicles in the transmission of salmonellosis in a community.

Methods for detecting arctic rabies virus in dilution series of field samples.

A modified first passage cell culture method, mouse inoculation test, and ELISA were compared for the detection of rabies in serially diluted field samples. Each original specimen contained rabies antigen, individually identified as an arctic strain by monoclonal antibodies. In 47% of the samples tested in cell cultures, the end-point titer was increased as a result of the first passage. The cell culture method gave higher titers than the mouse inoculation test or ELISA (P less than 0.05 and P less than 0.01, respectively).