Enteric Viruses and Pepper Mild Mottle Virus Show Significant Correlation in Select Mid-Atlantic Agricultural Waters

Enteric viruses (EV) are the largest contributors to foodborne illness and outbreaks globally. Their ability to persist in the environment, coupled with the challenges experienced in environmental monitoring create a critical aperture through which agricultural crops may become contaminated. This study involved a seventeen-month investigation of select human enteric viruses and viral indicators in non-traditional irrigation water sources, surface and reclaimed waters, in the Mid-Atlantic region of the United States. Real-time quantitative PCR was used for detection of Aichi virus, hepatitis A virus, noroviruses GI and GII. Pepper mild mottle virus (PMMoV), a common viral indicator of human fecal contamination, was also evaluated along with atmospheric (air and water temperature, cloud cover, and precipitation 24 h, 7 d and 14 d prior to sample collection) and physicochemical (dissolved oxygen, pH, salinity and turbidity) data to determine if there were any association between EV and measured parameters. EV were detected more frequently in reclaimed waters (32%, n=22) than in surface waters (4%, n=49) similar to PMMoV detection frequency in surface (33%, n=42) and reclaimed (67%, n=21) water. Our data show a significant correlation between EV and PMMoV (R2=0.628; p<0.05) detection in reclaimed water samples, but not in surface waters (R2=0.476; p=0.78). Water salinity significantly affected the detection of both EV and PMMoV (p<0.05) as demonstrated by logistic regression analyses. These results provide relevant insights into the extent and degree of association between human enteric (pathogenic) viruses and water quality data in Mid-Atlantic surface and reclaimed waters as potential sources for agricultural irrigation. IMPORTANCE Microbiological analysis of agricultural waters is fundamental to ensure microbial food safety. The highly variable nature of non-traditional sources of irrigation water are particularly difficult to test for the presence of viruses. Multiple characteristics influence viral persistence in a water source as well as affect the recovery and detection methods which are employed. Testing for a suite of viruses in water samples is often too costly and labor intensive, making identification of suitable indicators for viral pathogen contamination necessary. The results from this study address two critical data gaps: enteric virus prevalence in surface and reclaimed waters of the Mid-Atlantic region of the United States and subsequent evaluation of physicochemical and atmospheric parameters used to inform the potential for use of indicators of viral contamination.