Abstract
Hepatitis E virus (HEV), particularly zoonotic genotype 3, is present in environmental waters worldwide, especially in industrialized countries. Thus, monitoring the presence of HEV in wastewater treatment plants (WWTPs) is an emerging topic due to the importance of reusing water on a global level. Given the limited data, this study aimed to monitor the occurrence of HEV in influent and effluent water in waste- and drinking-water treatment plants (WWTPs and DWTPs). To this end, different procedures to concentrate HEV in influent and effluent water from WWTPs and DWTPs were initially evaluated. The evaluated procedures resulted in average HEV recoveries of 15.2, 19.9, and 16.9% in influent, effluent, and drinking water samples, respectively, with detection limits ranging from 103 to 104 international units (IU)/L. Then, a one-year pilot study was performed to evaluate the performance of the selected concentration method coupled with three RT-qPCR assays in influent and effluent water samples from four different WWTPs. HEV prevalence in influent water varied based on both the RT-qPCR assay and WWTP, while HEV was not detected in effluent water samples. In addition, HEV prevalence using only RT-qPCR3 was evaluated in influent (n = 62) and effluent samples (n = 52) from four WWTPs as well as influent (n = 28) and effluent (n = 28) waters from two DWTPs. The present study demonstrated that HEV circulated in the Valencian region at around 30.65% with average concentrations of 6.3 × 103 IU/L. HEV was only detected in influent wastewater samples, effluent samples from WWTPs and influent and effluent samples from DWTPs were negative. However, given that the infective dose in waterborne epidemics settings is not yet known and the low sensibility of the assay, unfortunately, no direct conclusion could be achieved on the risk assessment of environmental contamination.
Highlights
Hepatitis E virus (HEV) is a human enteric virus that mainly causes self-limiting acute viral hepatitis
This study initially evaluated the performances of different concentration methods, RNA extraction kits, and RT-qPCR protocols in detecting and quantifying HEV in influent and effluent wastewater samples as well as in drinking water samples (Graphical Abstract)
The first WHO international standard for HEV nucleic acid amplification technique (NAT)-based assays was purchased from Paul-Ehrlich-Institut (Germany). This standard corresponds to HEV genotype 3a positive plasma measured in international units (IU) and containing 250,000 IU/mL and it was used for RTqPCR quantification, as detailed below (Baylis et al, 2013)
Summary
Hepatitis E virus (HEV) is a human enteric virus that mainly causes self-limiting acute viral hepatitis. HEV G3, G4, and G7 are zoonotic genotypes that infect humans and animals and have been isolated in different animal species, especially in pigs (Van der Poel, 2014; Sooryanarain and Meng, 2019). HEV G1 and G2 are predominantly transmitted via the fecal-oral route in Asia, Africa, and Central America, usually through the consumption of contaminated drinking water (Khuroo et al, 2016; Van der Poel and Rzezutka, 2019). HEV G3 and G4 are endemic in industrialized countries and transmitted primarily via the consumption of animal meats or direct contact with infected animals (Sooryanarain and Meng, 2019)
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