Enteric viruses in raw vegetables and groundwater used for irrigation in South Korea

Raw vegetables irrigated with groundwater that may contain enteric viruses can be associated with food-borne viral disease outbreaks. In this study, we performed reverse transcription-PCR (RT-PCR) and cell culture-PCR to monitor the occurrence of enteric viruses in groundwater samples and in raw vegetables that were cultivated using that groundwater in South Korea. Samples were collected 10 times from three farms located in Gyeonggi Province, South Korea. RT-PCR and cell culture-PCR were performed to detect adenoviruses (AdVs), enteroviruses (EVs), noroviruses (NoVs), and rotaviruses, followed by sequence analyses of the detected strains. Of the 29 groundwater samples and the 30 vegetable samples, five (17%) and three (10%) were positive for enteric viruses, respectively. AdVs were the most frequently detected viruses in four groundwater and three vegetable samples. EVs and NoVs were detected in only one groundwater sample and one spinach sample, respectively. The occurrence of enteric viruses in groundwater and vegetable samples was not correlated with the water temperature and the levels of indicator bacteria, respectively. Phylogenetic analysis indicated that most of the detected AdVs were temporally distributed, irrespective of sample type. Our results indicate that raw vegetables may be contaminated with a broad range of enteric viruses, which may originate from virus-infected farmers and virus-contaminated irrigation water, and these vegetables may act as a potential vector of food-borne viral transmission.