Orthohepevirus A, also known as the hepatitis E virus (HEV), is endemic in Europe. HEV is divided into eight genotypes (HEV-1 to -8). Zoonotic HEV-3 is predominant in Europe and can further be differentiated into three monophyletic clades 3efg (group 1), 3abchijklm (group 2) and 3ra (rabbit HEV). Information about the distribution on the virus subtype level and possible associations with disease severity in Germany is scarce.
A recent study from Germany analyzed all HEV RNA positive samples sent to the National Consultant Laboratory between 2010 and 2019. They were able to genotype 936 samples and 803 of these could be matched with corresponding national surveillance data. HEV-3c was found to be the dominant subtype, accounting for 67.3% of all evaluated infections. Less frequently detected subtypes were HEV-3f (14.3%), HEV-3e (9.7%) and HEV-3i (4.0%). The proportion of HEV-3 group 2 strains has increased over time. Patients infected with HEV-3 group 1 strains were more likely to present with jaundice, upper abdominal pain and fever in comparison with group 2. Strikingly, hospitalisation (odds ratio 2) and death due to Hepatitis E (odds ratio 8) were also more often observed in HEV-3 group 1 infected patients. Of note, strains with identical sequences infecting several patients were rarely found.
The authors conclude that infections with HEV-3 group 1 strains are more severe, while detection of HEV-3 group 2 increased over time. This might be due to higher awareness of physicians leading to more frequent diagnosis of hepatitis E cases with asymptomatic or mild courses. The high genetic diversity of HEV strains and the space-time distribution is compatible with a foodborne zoonosis with supra-regional distribution of the infection vehicle (i.e. pork products). The risk of zoonotic/alimentary transmission still needs to be better communicated to vulnerable patients, i.e. immunocompromised individuals.
This study is published open access in Emerging Microbes & Infections, December 2022, Volume 11(1), pages 1754-1763, and can be accessed under the following link:
https://doi.org/10.1080/22221751.2022.2091479
