In an outbreak of gastroenteritis on board a cruise ship 251 passengers and 51 crew were affected and consulted the ship's surgeon during a 14-day period. There was a significant association between consumption of cabin tap water and reported illness in passengers. Enterotoxigenic Escherichia coli were isolated from passengers and crew and coliforms were found in the main water storage tank. Contamination of inadequately chlorinated water by sewage was the most likely source of infection.
A low level of reported illness and late recognition of the outbreak delayed investigation of what was probably the latest in a series of outbreaks of gastrointestinal illness on board this ship. There is a need for a national surveillance programme which would monitor the extent of illness on board passenger cruise ships as well as a standard approach to the action taken when levels of reported illness rise above a defined level.