Norwalk-like virus and bacterial pathogens associated with cases of gastroenteritis onboard a US Navy Ship

Acute gastroenteritis is a potential cause of substantial morbidity in U.S. military personnel during deployment. This study investigated the microbia l causes of diarrhea in U.S. troops on exercises in Southeast Asia aboard t he U.S.S. Germantown from March through May 1996. A total of 49 (7%) patien ts with diarrhea reported to sick call during a S-month deployment involvin g 721 personnel. Diarrheal samples from 49 patients were subjected to bacte rial and parasitologic examination, but sufficient samples from only 47 of 49 were available for analysis of the presence of Norwalk-like virus (NLV). Of the 49 diarrhea cases, 10 (20.4%) appeared to be due to bacterial etiol ogy alone, 10 (20.4%) due to bacteria and the prototype Taunton agent (TNA) , 11 (22.4%) due to TNA only, and 4 (8.0%) due to parasites. Norwalk-like v irus RNA was present in 21 (45%) of 47 stool samples from the diarrhea case s, 10 with bacterial etiologies and 11 without bacterial or parasitic etiol ogies. No pathogen was detected in 14 (29%) of the cases. Four of the contr ols showed the presence of parasitic organisms. Of the 11 cases in which en terotoxigenic Escherichia coli was isolated, 8 were positive for colonizati on factor antigen (CFA/IV), and 3 were CFA-negative. The bacterial pathogen s tested were all susceptible to gentamicin, and furadantin, but were resis tant to ceftriaxone and norfloxacin, including 75% of the Campylobacter spp . These data support the view that the major cause of diarrhea for troops d eployed in this geographic area is most likely NLVs.