Abstract
Diarrhoea, abdominal pain, malaise and fever affected 75 of the 88 conscript soldiers in Utti, Finland after an outdoors infantry drill. Campylobacter jejuni, heat-stable serotype 3/43/59, was isolated from 37 out of 63 men investigated. A clear serological response was evident in the risk group and negligible in the control group. The entire population at risk was interviewed. The outbreak was associated with the consumption of untreated surface water. C. jejuni, heat-stable serotype 3/43/59, was isolated on two occasions from the water source.