Norovirus Gastroenteritis Outbreak is Associated with Contaminated Drinking Water in South China

Noroviruses (NoVs) cause gastroenteritis in all age groups. To investigate an acute gastroenteritis outbreak in Shenzhen, South China, we analyzed the presence of NoVs in fecal specimens and drinking water samples. Viral RNAs were extracted from fecal suspensions and water concentrates made by membrane adsorption-elution, and NoV was detected by reverse transcription-polymerase chain reaction (RT-PCR). Among the 43 diseased workers at the two factories and one construction site, NoVs were detected in 19 out of 28 stool specimens (68%) and 3 out of 16 water samples (19%). Importantly, the six NoV strains identified from the water and the stool samples share over 99% sequence identity and all belong to GII 4 viruses. Epidemiological survey also identified a water pipe breakage possibly causing the water contamination, and confirmed that the contaminated drinking water largely contributed to the NoV gastroenteritis outbreak. To our knowledge, this is the first time that a viral concentration and detection method for waterborne NoV is applied to a gastroenteritis outbreak in China.