Shipboard impact of a probable Norwalk virus outbreak from coastal Japan.

Abstract

Abstract. Norwalk virus has been implicated in shipboard diarrheal disease outbreaks throughout Asia. A large outbreak of suspected Norwalk virus was investigated on a U.S. Naval aircraft carrier following the clinical recognition of 450 cases of gastroenteritis over a 2-week period (September 14-28, 1997) during coastal exercises. A random sampling of 44 cases from 450 personnel who sought medical attention was compared with 19 controls. Junior enlisted sailors and marines comprised 97% of all cases. There was no evidence of shipboard geographic clustering of cases. Furthermore, no single food type was associated with illness on the basis of comparative analysis (cases versus controls). Principal case signs and symptoms reported included watery stools (89%), nausea (82%), and vomiting (77%). Anecdotal reports indicated Ͼ 50% of the cases received rehydration therapy. An absence of fever was also noted in 32% of the cases and only 5% had blood in their stools. The mean duration of illness was 37 hr, with a range of 3-96 hr. Laboratory findings based on reverse transcription-polymerase chain reaction and Southern hybridization methods showed that 21 (72%) of 29 patients had evidence of the UK2 prototype of the Norwalk virus. A cross-sectional study of 131 crew members from the ships population (n ϭ 4,200) showed an attack rate of 44%. Attack rate is a variant of an incident rate applied to a narrowly defined population observed for a limited period of time, such as during an outbreak. The numerator is people who get sick and the denominator is people (population) at risk. An extrapolation of these findings suggests as many as 1,806 sailors may have been affected during the outbreak, of which only 26% (of the 57 outbreak related cases) where identified from sick call records. There was no difference in the mean ages between outbreak and non-outbreak affected crewmen, or geographic clustering based on berthing or work spaces. Outbreak-related cases reported signs and symptoms of watery-stools (79%), nausea (65%), and vomiting (47%). The mean duration of illness was 28 hr, ranging from 2 to 96 hr. Thirty-one percent of outbreak affected cases reported a sick call visit. Loss of work was reported by 39% of the outbreak affected population. This report documents the epidemic potential of Norwalk virus and the associated impact on fleet operational readiness. Additionally, that this outbreak occurred against a background of 3 other consecutive gastroenteritis outbreaks onboard the same ship

Incidence, Etiology, and Impact of Diarrhea Among Long-Term Travelers (Us Military and Similar Populations): A Systematic Review

“…Bacterial and viral agents having the potential to cause explosive and debilitating outbreaks may be as important, from a military perspective, because these agents cause the heavy burden of endemic disease. 43,53,54 In this respect, a study conducted among Israeli Defense Force troops during a routine deployment period found that, while sporadic cases of disease were caused by a number of different pathogens, most outbreaks were associated with Shigella, norovirus, and Salmonella. 55 Furthermore, impact of these agents with epidemic potential have been anecdotally described in a number of studies, including a study among United States Air Force personnel in this review that reported that onset of diarrheal illness in 5 of 222 airmen on 1 day had an adverse affect on operations, 36 and another study reported a flight mission was aborted mid-flight because of sudden onset of gastrointestinal illness in the pilot.…”

The epidemiology of norovirus gastroenteritis in China: disease burden and distribution of genotypes

“…AGE remains an unmet concern in military forces. Outbreaks due to NoVs infection have been reported in many countries, for instance, an outbreak involving 450 cases of AGE occurred on a US Naval aircraft carrier in 1997 [28]. AGE outbreaks have been reported in British [29], French [30], Singapore [31] and Chinese [32] military units.…”

Noroviruses : A Challenge for Military Forces

“…Since then norovirus outbreaks in military personnel have regularly been reported in the literature (Table 3) [5,[16][17][18][19][20][21][22][23].…”