Hepatitis E Virus Occurrence in Pigs Slaughtered in Italy

Abstract

In Europe, foodborne transmission has been clearly associated to sporadic cases and small clusters of hepatitis E in humans linked to the consumption of contaminated pig liver sausages, raw venison, or undercooked wild boar meat. In Europe, zoonotic HEV-genotype 3 strains are widespread in pig farms but little information is available on the prevalence of HEV positive pigs at slaughterhouse. In the present study, the prevalence of HEV-RNA positive pigs was assessed on 585 animals from 4 abattoirs located across Italy. Twenty-one pigs (3.6%) tested positive for HEV in either feces or liver by real-time RT-PCR. In these 21 pigs, eight diaphragm muscles resulted positive for HEV-RNA. Among animals collected in one abattoir, 4 out of 91 plasma tested positive for HEV-RNA. ELISA tests for the detection of total antibodies against HEV showed a high seroprevalence (76.8%), confirming the frequent exposure of pigs to the virus. The phylogenetic analyses conducted on sequences of both ORF1 and ORF2 fragments, shows the circulation of HEV-3c and of a novel unclassified subtype. This study provides information on HEV occurrence in pigs at the slaughterhouse, confirming that muscles are rarely contaminated by HEV-RNA compared to liver, which is the most frequently positive for HEV.

Keywords: Italy; abattoir; genotype 3; hepatitis E virus; pigs; slaughterhouse; zoonosis.

Figure 1

Maximum likelihood phylogenetic tree based on 328 nt fragment within the HEV ORF2 region of HEV-3 strains from human, pig and wild boar including HEV-3 reference strains. The HEV-4 strain was used as an outgroup. The Italian strains sequenced in this study are indicated by a black circle. Bootstraps values > 70 are indicated at their respective nodes. Representative porcine, human, wild boar and monkey strains are included. Each entry includes host (Hu: human, Sw: swine and Wb: wild boar), accession number and countries origin of strains.