Outbreak of viral gastroenteritis due to sewage-contaminated drinking water

In August 1998, a large outbreak of gastroenteritis occurred in a Swiss vil lage of 3500 inhabitants whereof more than 50% were affected. A high contam ination of drinking water with faecal coliforms revealed a defect in the wa ste water system. The objective of the present study was to investigate the outbreak in respect of the presence of human pathogenic viruses. Drinking water and clinical samples from patients were examined for the presence of Norwalk-like viruses' (NLVs) and enteroviruses. NLVs and enteroviruses were detected by reverse transcription-polymerase chain reaction (RT-PCR) in on e of two drinking water samples. Five of seven stool samples from ill perso ns were positive for NLVs. Typing of NLV-specific RT-PCR products by DNA se quencing revealed the presence of an identical genogroup-1 strain closely r elated to Southampton virus in both the water and one of the stool samples. A genogroup-2 NLV strain was identified in all positive stool samples. The enteroviral amplicon showed high sequence similarity with swine vesicular disease virus. These results demonstrate that the drinking water was highly contaminated with enteric viruses and that at least two NLV strains were i nvolved in this outbreak of gastroenteritis. (C) 2000 Elsevier Science B.V. All rights reserved.