Concurrent Detection of Human Norovirus and Bacterial Pathogens in Water Samples from an Agricultural Region in Central California Coast.

Peng Tian,Qianqian Li,Lisa Gorski,Michael B Cooley,David Yang,Dapeng Wang,Lei Shan,Bertram G Lee,Beatriz Quiñones

doi:10.3389/fmicb.2017.01560

Abstract

Bacterial pathogens and human norovirus (HuNoV) are major cause for acute gastroenteritis caused by contaminated food and water. Public waterways can become contaminated from a variety of sources and flood after heavy rain events, leading to pathogen contamination of produce fields. We initiated a survey of several public watersheds in a major leafy green produce production region of the Central California Coast to determine the prevalence of HuNoV as well as bacterial pathogens. Moore swabs were used to collect environmental samples bi-monthly at over 30 sampling sites in the region. High prevalence of HuNoV and bacterial pathogens were detected in environmental water samples in the region. The overall detection rates of HuNoV, O157 Shiga toxin-producing Escherichia coli (STEC), non-O157 STEC, Salmonella, and Listeria were 25.58, 7.91, 9.42, 59.65, and 44.30%, respectively. The detection rates of Salmonella and L. monocytogenes were significantly higher in the spring. Fall and spring had elevated detection rates of O157 STEC. The overall detection rates of non-O157 STEC in the fall were lower than the other seasons but not significant. The overall detection rates of HuNoV were highest in fall, followed by spring and winter, with summer being lowest and significantly lower than other seasons. This study presented the first study of evaluating the correlation between the detection rate of HuNoV and the detection rates of four bacterial pathogens from environmental water. Overall, there was no significant difference in HuNoV detection rates between samples testing positive or negative for the four bacterial pathogens tested. Pathogens in animal-impacted and human-impacted areas were investigated. There were significant higher detection rates in animal-impacted areas than that of human-impacted areas for bacterial pathogens. However, there was no difference in HuNoV detection rates between these two areas. The overall detection levels of generic E. coli and detection rate of HuNoV showed no correlation.

Highlights

Human noroviruses are highly contagious pathogens and the major cause for acute non-bacterial gastroenteritis
Evaluation of Tulane virus (TV) Used as a Process Control Virus (PCV) for Environmental Water Samples
The detection rates of GI or GII human norovirus (HuNoV) were higher in samples without observed TV signal inhibition (24.8% for GI and 8.3% for GII) than in those with partial TV- inhibition (20.6% for GI and 5.9% for GII), and complete TV- inhibition (16.9% for GI and 3.6% for GII) samples, the differences were not statistically significant (p > 0.05)

Summary

Introduction

Human noroviruses are highly contagious pathogens and the major cause for acute non-bacterial gastroenteritis. It is possible that the produce was contaminated by bacterial pathogens and HuNoV via exposure to contaminated water from public waterways (rivers, lakes, ponds, streams, etc.). Public waterways can be contaminated by sewage containing enteric pathogens from the stool of infected patients. Wildlife is suspected as a potential a vector for pathogen bacteria for water contamination (Kirk et al, 2002; Jay et al, 2007; Gorski et al, 2013). These contaminated waterways can flood and overflow after large rain events, which may lead to pathogen transmission into the fields

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