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December 1991

A Large Nontypical Outbreak of Norwalk Virus: Gastroenteritis Associated With Exposing Celery to Nonpotable Water and With Citrobacter freundii

Author Affiliations

From the Epidemiology Services (Drs Warner and Carr and Ms Elmer), Bacteriology Function (Ms McCleskey), and Virology Function (Dr Davison), Epidemiology Division, US Air Force School of Aerospace Medicine, Human Systems Division (AFSC), Brooks Air Force Base, Tex; and the Department of Internal Medicine, Division of General Medicine, University of Texas Health Science Center at Houston (Dr Johnson). Dr Carr is now with the Occupational Medical Services, SmithKline Beecham, King of Prussia, Penn. Dr Elmer is in private practice, Boston, Mass.

Arch Intern Med. 1991;151(12):2419-2424. doi:10.1001/archinte.1991.00400120061010

The US Air Force Academy experienced a point-source outbreak of gastroenteritis originally believed to be caused by Salmonella. The overall attack rate was 48% among approximately 3000 cadets and staff. Food-specific attack rates implicated chicken salad. The odds ratio for chicken salad consumption in ill cadets was 10.7 (95% confidence interval: 8.2; 13.8). The celery component had been exposed to nonpotable water. Citrobacter freundii were statistically associated with consumption of the suspected vehicle and subsequent illness. Most aspects were consistent with the epidemiology of Norwalk gastroenteritis. However, the clinical presentation was not typical of reported outbreaks. One hundred five cadets required intravenous rehydration. Serum samples implicated Norwalk virus as the most probable cause of this outbreak. The Centers for Disease Control (Atlanta, Ga) recently began national surveillance for viral gastroenteritis. All outbreaks of gastroenteritis associated with nonpotable water should be investigated for evidence of viral cause.

(Arch Intern Med. 1991;151:2419-2424)

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