Surveillance for rat hepatitis E in wastewater networks, Italy

Correlation of hepatitis E and rat hepatitis E viruses urban wastewater monitoring and clinical cases

BACKGROUND

Wastewater pathogen monitoring is useful for surveillance of enteric pathogens. Information about the presence of Paslahepevirus balayani (HEV) and emergent Rocahepevirus ratti (RHEV) in untreated water and their correlation with clinical cases is scarce. Aim To longitudinally monitor HEV and RHEV in wastewater and to evaluate their possible correlation with human cases.

METHODS

This study was carried out in the city of Cordoba (southern Spain) from March 2021 to March 2023. HEV and RHEV occurrence were evaluated by PCR in three sample types: i) sera from patients with acute hepatitis attended at the reference hospital, ii) liver and faeces from urban rodents, and iii) grab sewage samples collected weekly from the municipal wastewater treatment plant.

RESULTS

We analysed 106 untreated wastewater samples, 304 individuals with acute hepatitis, and 20 rodents. HEV and RHEV were detected in only one (0.9 %) and almost all samples (94.3 %) of wastewater samples, respectively. A total of 22 cases of acute HEV infection (7.2 %) and two cases of RHEV (0.7 %) were detected from all acute hepatitis cases observed. Only RHEV was found in rodents, with a positive frequency of 55 %. The presence of HEV in wastewater coincided with the detection of one case in which the same HEV genotype was isolated. A concentration of HEV clinical cases between June and July of 2022 was observed but not detected in water. Both RHEV clinical cases were detected in summer 2022, but no correlation was found with wastewater detection.

CONCLUSIONS

Our study shows that there is no correlation between clinical cases and wastewater detection of HEV or RHEV.

Rocahepevirus ratti as an Emerging Cause of Acute Hepatitis Worldwide

The hepatitis E virus (HEV) is a widespread human infection that causes mainly acute infection and can evolve to a chronic manifestation in immunocompromised individuals. In addition to the common strains of hepatitis E virus (HEV-A), known as Paslahepevirus balayani, pathogenic to humans, a genetically highly divergent rat origin hepevirus (RHEV) can cause hepatitis possessing a potential risk of cross-species infection and zoonotic transmission. Rocahepevirus ratti, formerly known as Orthohepevirus C, is a single-stranded RNA virus, recently reassigned to Rocahepevirus genus in the Hepeviridae family, including genotypes C1 and C2. RHEV primarily infects rats but has been identified as a rodent zoonotic virus capable of infecting humans through the consumption of contaminated food or water, causing both acute and chronic hepatitis cases in both animals and humans. This review compiles data concluding that 60% (295/489) of RHEV infections are found in Asia, being the continent with the highest zoonotic and transmission potential. Asia not only has the most animal cases but also 16 out of 21 human infections worldwide. Europe follows with 26% (128/489) of RHEV infections in animals, resulting in four human cases out of twenty-one globally. Phylogenetic analysis and genomic sequencing will be employed to gather global data, determine epidemiology, and assess geographical distribution. This information will enhance diagnostic accuracy, pathogenesis understanding, and help prevent cross-species transmission, particularly to humans.