Hepatitis E Outbreak in the Central Part of Italy Sustained by Multiple HEV Genotype 3 Strains, June-December 2019.

Anna Garbuglia,Maria Capobianchi,Anna Ciccaglione,Rinalda Mariani,Barbara Binda,Daniele Lapa,Umbertina Villano,Roberto Bruni,Paola Scognamiglio,Stefania D’Amato,Francesca De Paulis,Francesco Vairo,Elisabetta Madonna,Alessandro Grimaldi,Giovanna Picchi

doi:10.3390/v13061159

Abstract

In European countries, autochthonous acute hepatitis E cases are caused by Hepatitis E Virus (HEV) genotype 3 and are usually observed as sporadic cases. In mid/late September 2019, a hepatitis E outbreak caused by HEV genotype 3 was recognized by detection of identical/highly similar HEV sequences in some hepatitis E cases from two Italian regions, Abruzzo and Lazio, with most cases from this latter region showing a link with Abruzzo. Overall, 47 cases of HEV infection were finally observed with onsets from 8 June 2019 to 6 December 2019; they represent a marked increase as compared with just a few cases in the same period of time in the past years and in the same areas. HEV sequencing was successful in 35 cases. The phylogenetic analysis of the viral sequences showed 30 of them grouped in three distinct molecular clusters, termed A, B, and C: strains in cluster A and B were of subtype 3e and strains in cluster C were of subtype 3f. No strains detected in Abruzzo in the past years clustered with the strains involved in the present outbreak. The outbreak curve showed partially overlapped temporal distribution of the three clusters. Analysis of collected epidemiological data identified pork products as the most likely source of the outbreak. Overall, the findings suggest that the outbreak might have been caused by newly and almost simultaneously introduced strains not previously circulating in this area, which are possibly harbored by pork products or live animals imported from outside Abruzzo. This possibility deserves further studies in this area in order to monitor the circulation of HEV in human cases as well as in pigs and wild boars.

Highlights

Hepatitis E Virus (HEV), responsible for human hepatitis E, is classified in the Hepeviridae family, which includes viruses infecting either humans or animal species or both [1]
- Any transplanted patient or blood donor with a HEV RNA positive serum sample collected after 8 June 2019 and a viral sequence in the ORF2 region located in a phylogenetic tree in a different branch vs. the following three HEV reference sequences: Accession number MN497623, MN537879, and MN737483 and with no clustering with other sequences collected after 8 June 2019
The outbreak was first recognized in mid/late September by the comparison of viral sequences obtained from anti-HEV IgM positive acute hepatitis patients with onset between 8 June and 21 September 2019

Summary

Introduction

Hepatitis E Virus (HEV), responsible for human hepatitis E, is classified in the Hepeviridae family, which includes viruses infecting either humans or animal species or both [1]. Most HEVs detected in humans have been so far classified into the Orthohepevirus A species until a recent report that demonstrated frequent transmission to humans of rat HEV, which is a member of the Orthohepevirus C species [2]. It remains to be investigated how widespread rat HEV infection is in humans worldwide [3]. No further HEV-7 related cases have been so far documented and so it is likely this latter genotype, for which its natural host is camel, could be transmitted under exceptional circumstances [5]

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Conclusion