The family Hepeviridae is separated into four species. The best-known is Orthohepevirus A (hepatitis E virus, HEV-A) which is meanwhile recognized as the main causative agent of acute hepatitis globally. The other three species Orthohepevirus B-D were so far mainly found in birds, rodents, ferrets and bats. However, in 2018 the first zoonotic case of Orthohepevirus C genotype 1 (HEV-C1, rat HEV) infection was described in Hong Kong and shortly after that, a second transmission in an individual with travel history to Central Africa was reported. The situation in Hong Kong was followed up by intensive surveillance efforts and further 16 human cases were found as of 2021. Only recently, the first three cases in Europe were found in Spain.
A recent study led by Dr. Mirko Faber and Dr. Mathias Schemmerer looked for evidence of human HEV-C1 infections in archived samples of the German population collected between 2000 and 2020. Because of the hitherto extremely low frequency of such cases, detection of HEV-C1 seemed unlikely without appropriate preselection of samples. Hence, they aimed to increase the detection probability by focusing on HEV-A RNA negative individuals with evidence of acute hepatitis E (detectable anti-HEV-A IgM antibodies). Such a cohort could comprise a rat HEV prevalence of approximately 2.5% (95% CI: 0.06–13.1), given that the data reported in a study from Spain would be applicable to the situation in Germany. They tested 200 individuals with a broad-spectrum nested PCR that can detect HEV-A and -C RNA. They found four previously unnoticed HEV-A cases, but no HEV-C infection. Additionally, the team established a new highly sensitive HEV-C1-specific real-time quantitative PCR (RT-qPCR) with a lower limit of detection (LoD 95) of 6.73 copies per PCR reaction. However, analysis with this sensitive method still did not lead to the detection of HEV-C1 RNA in any of the samples.
Since they did not detect HEV-C1 in a cohort of patients with a high pre-test probability, the auhtors conclude that the frequency of rat HEV infections in the German population is –if anything– very low. Nevertheless, continued awareness and event driven screening for this emerging pathogen is highly warranted.
This study was published Viruses in March 2022 and can be accessed under the following link: https://www.mdpi.com/1999-4915/14/4/742