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 microbial causes of diarrhea in U.S. troops on exercises in Southeast Asia aboard the U.S.S. Germantown from March through May 1996. A total of 49 (7%) patients with diarrhea reported to sick call during a 3-month deployment involving 721 personnel. Diarrheal samples from 49 patients were subjected to bacterial 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 etiology 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 virus RNA was present in 21 (45%) of 47 stool samples from the diarrhea cases, 10 with bacterial etiologies and 11 without bacterial or parasitic etiologies. No pathogen was detected in 14 (29%) of the cases. Four of the controls showed the presence of parasitic organisms. Of the 11 cases in which enterotoxigenic Escherichia coli was isolated, 8 were positive for colonization factor antigen (CFA/IV), and 3 were CFA-negative. The bacterial pathogens tested were all susceptible to gentamicin, and furadantin, but were resistant to ceftriaxone and norfloxacin, including 75% of the Campylobacter spp. These data support the view that the major cause of diarrhea for troops deployed in this geographic area is most likely NLVs.