EPIDEMIOLOGY OF NORWALK VIRUS DURING AN OUTBREAK OF ACUTE GASTROENTERITIS ABOARD A US-AIRCRAFT-CARRIER

A large outbreak of acute gastroenteritis occurred over a 5-week perio d aboard an aircraft carrier. The estimated cumulative attack rate was 13% among the 4,500-man crew. Eight percent of the crew sought medica l attention, nearly all of whom missed 1 day or more of work. The risk of developing illness was 2 to 3 times greater for individuals living in more crowded sleeping quarters (>50 persons per compartment). Occu rrence of gastroenteritis was associated with a fourfold or more rise in Norwalk virus antibody levels, as measured by an enzyme-linked immu noassay utilizing a baculovirus expressed recombinant antigen. In addi tion, 27 nm Norwalk virus-like particles were visualized in two of six stools examined by immune electron microscopy. The presence of a low (<1:50) or a high (greater than or equal to 1:6,400) pre-illness antib ody level was associated with a lower incidence of illness. This inves tigation indicates that Norwalk virus can adversely impact operations of a military vessel and that crowding is a major risk factor in trans mission. (C) 1995 Wiley-Liss, Inc.