Written by Amine Nur Avan
The hepatitis E virus (HEV) is classified into the genus Orthohepevirus of the Hepeviridae family, consisting of 4 species, namely Orthohepevirus A, B, C and D. Orthohepevirus A is commonly associated with human infections. Within this species, there are 8 classified genotypes, of which genotypes 1, 2, 3 and 4 are the most frequently reported to infect humans. The species Orthohepevirus C, roughly classified into HEV-C1 and HEV-C2 clades, is widely circulated among rodents, but emerging evidence indicates possible transmission to humans. Orthohepevirus C (HEV-C1; rat HEV) have been associated with the development of acute and chronic hepatitis E in patients based on reports from different countries and regions. However, the exact routes how rat HEV is transmitted to humans remain unknown.
Although direct and indirect contact with rodents have been suggested as potential transmission routes, very few registered cases have involved such contact. Thus, alternative sources of infection have been postulated, potentially from an alternate host with which humans have more contact. A very recent study from Spain randomly selected and prospectively sampled domestic pigs from 5 intensive breeding system farms in Cordoba during May–June 2023. They included a total of 387 pigs in the study and found rat HEV in 44 pigs, an individual prevalence of 11.4%. These results indicate that pigs might be susceptible to rat HEV and could serve as viral intermediaries between rodents and humans. The authors recommend that Europe should evaluate the prevalence of rat HEV in farmed pigs to assess the risk to public health.
In parallel, another recent study investigated rat HEV prevalence in companion and stray cats and dogs in multiple districts across Hong Kong between January 2022 and December 2022. The team demonstrated that dogs and cats harbour antibodies reactive against rat HEV or a related antigen. The authors call for further studies to confirm the susceptibility of dogs and cats to rat HEV. Collectively, these two studies (from Asia and Europe) points to possible intermediate hosts of rat HEV that may transmit the viruses to humans, deserving future research to clarify.
Read the full articles:
Rios-Muñoz L, et al. Emerg Infect Dis. 2024 Apr;30(4):823-826. DOI: 10.3201/eid3004.231629
Shun EH, et al. Emerg Microbes Infect. 2024 Mar 29:2337671. DOI: 10.1080/22221751.2024.2337671
