Occurrence of enteric viruses in reclaimed and surface irrigation water: relationship with microbiological and physicochemical indicators

AimsTo assess the prevalence of enteric viruses in different irrigation water sources and in the irrigated produce, and the possible links with microbiological and physicochemical water characteristics. Methods and ResultsThe prevalence and levels of Escherichia coli, Norovirus (NoV) genogroup I (GI) and II (GII), as well as Hepatitis A virus were assessed in three types of water: surface water (surface-W), reclaimed water subjected to secondary treatment (secondary-W) and reclaimed water subjected to tertiary treatment (tertiary-W), as well as in zucchini irrigated with these irrigation water sources. Chemical oxygen demand (COD), turbidity, total suspended solids, alkalinity and maximum filterable volume (MFV) were also measured in the water. Higher prevalence of NoV in secondary-W (GI 100%, GII 556%) and tertiary-W (GI 917%, GII 667%) compared with surface-W (GI 584%, GII 222%) was observed. Nov GI showed positive correlation with E.coli (Spearman's correlation coefficient=068, P<001), and with some physicochemical parameters such as COD (052, P<001), turbidity (052, P<001) and MFV (054, P<001). Escherichia coli and enteric viruses were not detected in zucchini. ConclusionThere is a potential risk of contamination of crops with NoV when reclaimed water is used for irrigation. Significance and Impact of the StudyIncrease the knowledge on the prevalence of enteric viruses in different irrigation water sources, and its consequences for fresh produce safety.