Environmental Surveillance of Hepatitis E Virus and Rat Hepatitis E Virus in Portugal and Spain, 2020–2022

Hepatitis E virus (Paslahepevirus balayani [HEV]) is an important cause of acute viral hepatitis globally, with zoonotic genotypes linked to transmission through consumption of raw or undercooked swine meat or products. Recently, Rocahepevirus ratti (RHEV), member of Hepeviridae family, has emerged as a potential public health concern, with some human cases being reported. The present study aimed to investigate the presence of HEV, as well as RHEV in wastewaters from northern Portugal and Spain (nPS). Given the reported decline in HEV detection in swine from several regions of the world, we also aimed to explore HEV and RHEV in fattened swine fecal samples from the same region of the wastewaters. Between April 2020 and January 2022, a total of 44 wastewater samples were collected from wastewater treatment plants in nPS, alongside 400 fattened swine fecal samples from five farms of the same regions. Wastewater and swine fecal samples RNA extracts were screened for HEV using pangenotypic RT-qPCR and for RHEV using a RT-qPCR assay followed by characterization using nested RT-PCR. Regarding wastewaters, three tested positive for HEV, while 39 out of 44 tested positive for RHEV. Wastewater analysis in the Iberian Peninsula revealed a predominance of RHEV and a near absence of HEV. The absence of both viruses was observed in the swine fecal samples. This combined analysis showing near/total absence of HEV in wastewaters/fattened swine samples warrants further studies. High levels of RHEV in wastewater might also pose environmental transmission risks, particularly for individuals with occupational exposure, emphasizing the need for enhanced zoonotic virus surveillance in urban areas.