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ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Produce Safety and Microbiology Research » Research » Publications at this Location » Publication #308671

Research Project: Biology and Control of Human Pathogens on Fresh Produce

Location: Produce Safety and Microbiology Research

Title: Concurrent detection of human norovirus and bacterial pathogens in water samples from an agricultural region in Central California Coast

Author
item Tian, Peng
item Yang, David
item Lei, Shan - University Of Minnesota
item Wang, Dapeng - Xan Jiao Tong University
item Li, Qianqian - Shanghai Institute Of Technology
item Gorski, Lisa
item Lee, Bertram
item Quiñones, Beatriz
item Cooley, Michael - Mike

Submitted to: Frontiers in Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/2/2017
Publication Date: 8/21/2017
Citation: Tian, P., Yang, D., Lei, S., Wang, D., Li, Q., Gorski, L.A., Lee, B.G., Quinones, B., Cooley, M.B. 2017. Concurrent detection of human norovirus and bacterial pathogens in water samples from an agricultural region in Central California Coast. Frontiers in Microbiology. 8:1560. https://doi.org/10.3389/fmicb.2017.01560.
DOI: https://doi.org/10.3389/fmicb.2017.01560

Interpretive Summary: Human noroviruses (HuNoV) are highly contagious pathogens and is the main cause of acute gastroenteritis. In recent years, we have seen an increase in the number of HuNoV outbreaks, which correlates with the increased consumption of minimally-processed (e.g. raw) fruits and vegetables. One method by which produce has been known to become contaminated by HuNoV is via exposure to contaminated water from public waterways (rivers, lakes, ponds, streams, etc.). This exposure to contaminated water may occur in the course of heavy rains by which the waterways over-flood their banks into produce fields. Public waterways can become contaminated by HuNoV by a variety of ways, including exposure to sewage and runoff from livestock operations. After contamination, these water sources can act as reservoirs and allow HuNoV to persist over time. We initiated a survey of several public watersheds in a major leafy green production region of Central Coastal California to determine the prevalence of HuNoV as well as Shiga-toxin-producing E. coli (STEC), Salmonella, and L. monocytogenes. The overall detection rates of HuNoV, O157 STEC, non-O157 STEC, Salmonella, and Listeria were 25.58%, 7.91%, 9.42%, 59.65%, and 44.30%, respectively. The seasonal distributions of bacterial and viral pathogens were clearly different. The detection rates of Salmonella and L. monocytogenes were significantly higher in the spring. Fall and spring corresponded to elevated detection rates of O157 STEC. The overall detection rates of non-O157 STEC in fall was lower than the other seasons but not significant. The overall detection rates of HuNoV was highest in fall, followed by spring and winter, with summer being lowest and significantly lower than other seasons. There was no significant difference in HuNoV detection rates between samples testing positive or negative for the four bacterial pathogens tested. There were significant higher detection rates in animal-impacted areas than that of human-impacted areas for bacterial pathogens but not for HuNoV. There was no significant difference in levels of generic E coli in four seasons although the level was highest in summer and lowest in winter. The overall detection levels of generic E. coli and detection rate of HuNoV showed no correlation.

Technical Abstract: AIMS: To determine the prevalence of HuNoV and bacterial pathogens in public watersheds in a major leafy green produce production region of the Central California. Methods and Results: Moore swabs were used to collect environmental samples bi-monthly at over 30 sampling sites in the region. The overall detection rates of HuNoV, O157 STEC, non-O157 STEC, Salmonella, and Listeria were 25.58%, 7.91%, 9.42%, 59.65%, and 44.30%, respectively. The seasonal distributions of bacterial and viral pathogens were clearly different. The detection rates of Salmonella and L. monocytogenes were significantly higher in the spring. Fall and spring corresponded to elevated detection rates of O157 STEC. The overall detection rates of non-O157 STEC in fall was lower than the other seasons but not significant. The overall detection rates of HuNoV was highest in fall, followed by spring and winter, with summer being lowest and significantly lower than other seasons. There was no significant difference in HuNoV detection rates between samples testing positive or negative for the four bacterial pathogens tested. There were significant higher detection rates in animal-impacted areas than that of human-impacted areas for bacterial pathogens but not for HuNoV. There was no significant difference in levels of generic E coli in four seasons although the level was highest in summer and lowest in winter. The overall detection levels of generic E. coli and detection rate of HuNoV showed no correlation. Conclusions: High prevalence of HuNoV and bacterial pathogens was detected in environmental water samples in the region. There was no correlation between detection rates of HuNoV and bacterial pathogens. Generic E coli count was not a good indicator for HuNoV contamination in environmental water in the region. Significance and Impact of the study: This study presents the 1st study of concurrent detection of HuNoV and bacterial pathogens from environmental water by using Moore swab. It is also the 1st report demonstrated there was no correlations between the detection rate of HuNoV and the detection rates of four bacterial pathogens.