Autochthone Hepatitis-E-Virus-Infektion als Ursache der akuten Hepatitis in Deutschland - eine Kasuistik

Seroprevalence of hepatitis E virus (HEV) in humans living in high pig density areas of Germany

An increase in acute autochthonous hepatitis E virus (HEV) infections has been recorded in Germany. These are suspected to be zoonotically transmitted from wild boar, deer and domestic pig. The latter may represent a major reservoir for HEV. In this study, 537 sera from humans living in Westphalia and Lower Saxony, representing areas of high pig density in Germany, were tested for the presence of HEV-specific antibodies. Among them were 302 individuals with occupational, direct contact to pigs and 235 individuals without direct contact to pigs. Two commercial tests and one in-house assay were applied for the detection of HEV-specific immunoglobulin G (IgG) antibodies. Sera were also tested in an assay that detects all classes of HEV-specific antibodies. Depending on the test used, the seroprevalence ranged from 4.1 to 27.9 %. Exposition to pigs was found to be associated with a significantly higher seroprevalence in subjects with contact to pigs (13.2-32.8 %) compared with that in non-exposed humans (7.7-21.7 %). In particular, individuals younger than 40 years with occupational exposure exhibited a markedly higher HEV seroprevalence compared with non-exposed individuals of that age group. In general, HEV seroprevalence increased with age resulting in a similar prevalence level in the age group of ≥ 50 years for exposed and non-exposed individuals. Analysis of all sera by a commercial anti-HEV IgM ELISA revealed 35 positive and 25 borderline samples. However, only one positive serum could be confirmed by an IgM line assay. Selected samples from IgM and/or IgG as well as total HEV antibody-positive individuals were also tested for the presence of HEV RNA. In one of the 78 samples, the only IgM ELISA positive and IgM line assay confirmed sample, RNA of HEV genotype 3 was detected. This sequence has high similarity to HEV sequences obtained from wild boars and domestic pigs from Germany and The Netherlands. This study demonstrates that in addition to the consumption of raw or undercooked meat, direct contact to pigs has to be considered as an additional risk factor for HEV infection.

Seroprevalence study in forestry workers from eastern Germany using novel genotype 3- and rat hepatitis E virus-specific immunoglobulin G ELISAs

Hepatitis E virus (HEV) is the causative agent of an acute self-limiting hepatitis in humans. In industrialized countries, autochthonous cases are linked to zoonotic transmission from domestic pigs, wild boar and red deer. The main route of human infection presumably is consumption of contaminated meat. Farmers, slaughterers and veterinarians are expected to be risk groups as they work close to potentially infected animals. In this study, we tested four Escherichia coli-expressed segments of the capsid protein (CP) of a German wild boar-derived HEV genotype 3 strain for their diagnostic value in an indirect immunoglobulin G (IgG) ELISA. In an initial validation experiment, a carboxy-terminal CP segment spanning amino acid (aa) residues 326-608 outperformed the other segments harbouring aa residues 112-608, 326-660 and 112-335. Based on this segment, an indirect ELISA for detection of anti-HEV IgG antibodies in human sera was established and validated using a commercial line immunoassay as reference assay. A total of 563 sera from forestry workers of all forestry offices of Brandenburg, eastern Germany and 301 sera of blood donors from eastern Germany were surveyed using these assays. The commercial test revealed seroprevalence rates of 11% for blood donors and 18% for forestry workers. These rates are in line with data obtained by the in-house test (12 and 21%). Hence, the in-house test performed strikingly similar to the commercial test (sensitivity 0.9318, specificity 0.9542). An initial screening of forestry worker and blood donor sera with a corresponding CP segment of the recently discovered Norway rat-associated HEV revealed several strong positive sera exclusively in the forestry worker panel. Future investigations have to prove the performance of this novel IgG ELISA in large-scale seroepidemiological studies. In addition, the observed elevated seroprevalence in a forestry worker group has to be confirmed by studies on groups of forestry workers from other regions. The epidemiological role of ratHEV in human disease should be assessed in a large-scale study of risk and non-risk groups.

Detection of hepatitis E virus (HEV) from porcine livers in Southeastern Germany and high sequence homology to human HEV isolates

BACKGROUND

Hepatitis E virus (HEV) has been identified as an emerging cause of infectious hepatitis over the last years in developed countries. In contrast to travel associated hepatitis E, zoonotic sources of infection are suspected for autochthonous cases in Europe.

OBJECTIVE

Since pigs are known reservoirs of HEV, we tested porcine livers sold as food in Southeastern Germany for the presence of hepatitis E virus RNA.

STUDY DESIGN

We purchased 200 porcine liver samples in 81 butcher shops and grocery stores in Regensburg, Germany. Nucleic acid preparations were tested for the presence of HEV RNA by quantitative real-time PCR (RT-qPCR). HEV isolates from positive samples were characterized by partial sequencing of ORF1 and ORF2 regions in the HEV genome and by phylogenetic analysis.

RESULTS

Specimens from eight (4%) of 200 purchased pig livers had detectable HEV RNA amounts. Sequence determination and phylogenetic analysis allowed two novel isolates to be classified as HEV genotype 3, subgenotype 3a (swR437) and 3c (swR269), respectively. Both novel swine HEV isolates showed high sequence homology to isolates obtained from patients with acute HEV infection from the same geographic region.

CONCLUSIONS

These results support the suggested role of undercooked pig products in food as a source of zoonotic HEV infection for humans. It remains to be clarified if this mechanism of transmission is responsible for the surprisingly high anti-HEV IgG prevalence recently observed in some European countries and the USA.