 Noroviruses have also been implicated in several military outbreaks. The Desert Shield virus DSV isolated in US troops in the 1991 Gulf War was subsequently identified as a Norovirus. Similarly the recently reported mysterious attacks of acute gastroenteritis affecting the British troops in Afghanistan were also caused by a Norovirus. Large outbreaks of Norovirus-associated gastroenteritis are common on US Navy ships, similar to those that occurred on board cruise ship lines. Surveillance of acute gastroenteritis on board five US Navy combat ships in 1998-1999 showed that all the ships experienced large outbreaks of Norovirus acute gastroenteritis during their deployment in the Pacific and Indian Oceans, following port visits. Because of the rapid spread of the disease, many departments and units on board the ships were unable to function during the peak of the outbreaks. 