Water-borne outbreak of campylobacter gastroenteritis

An outbreak of gastroenteritis affecting 234 pupils and 23 staff at a boarding school occurred over a period of 8 weeks. Campylobacter spp. were isolated from pupils and staff, and from two samples of cold water taken from an open-topped storage tank which supplied predominantly unchlorinated water to the main school building. The two isolates from water were of the same serotype. This serotype was the commonest of the three serotypes of Campylobacter jejuni detected in isolates from pupils and staff. There was a highly significant association between consumption of water from the cold water storage tank and reported illness in staff. Attack rates in pupils corresponded closely with the extent of distribution of this water-supply to the main residential houses. Contamination of water by faecal material from birds or bats was the most likely source of infection.