Epidemiology and Infection

An outbreak of viral gastroenteritis associated with consumption of sandwiches: implications for the control of transmission by food handlers

U. D. PARASHAR a1a2c1, L. DOW a3, R. L. FANKHAUSER a2, C. D. HUMPHREY a4, J. MILLER a3, T. ANDO a2, K. S. WILLIAMS a5, C. R. EDDY a3, J. S. NOEL a2, T. INGRAM a3, J. S. BRESEE a2, S. S. MONROE a2 and R. I. GLASS a2
a1 Epidemic Intelligence Service, Epidemiology Program Office, Centers for Disease Control and Prevention (CDC), Atlanta, GA, USA
a2 Viral Gastroenteritis Section, Division of Viral and Rickettsial Diseases, National Center for Infectious Diseases (NCID), CDC, Atlanta, GA 30333, USA
a3 Hamilton County General Health District, Cincinnati, OH, USA
a4 Infectious Diseases Pathology Unit, NCID, CDC, Atlanta, GA, USA
a5 Family Medicine Program, Brown University School of Medicine, Providence, RI, USA


Although food handlers are often implicated as the source of infection in outbreaks of food-borne viral gastroenteritis, little is known about the timing of infectivity in relation to illness. We investigated a gastroenteritis outbreak among employees of a manufacturing company and found an association (RR=14·1, 95% CI=2·0–97·3) between disease and eating sandwiches prepared by 6 food handlers, 1 of whom reported gastroenteritis which had subsided 4 days earlier. Norwalk-like viruses were detected by electron microscopy or reverse transcriptase-polymerase chain reaction (RT-PCR) in stool specimens from several company employees, the sick food handler whose specimen was obtained 10 days after resolution of illness, and an asymptomatic food handler. All RT-PCR product sequences were identical, suggesting a common source of infection. These data support observations from recent volunteer studies that current recommendations to exclude food handlers from work for 48–72 h after recovery from illness may not always prevent transmission of Norwalk-like viruses because virus can be shed up to 10 days after illness or while exhibiting no symptoms.

(Accepted May 13 1998)

c1 Author for correspondence.