Persistence of hepatitis E virus (HEV) in an Italian swine farm between 2017-2019.

Hepatitis E virus (HEV), is the causative agent of hepatitis E in humans. The disease is an acute hepatitis, generally self-limited which can become chronic in immunosuppressed patients. Among the 8 genotypes of HEV belonging to Orthohepevirus A, genotypes HEV-1 and HEV-2 infect only humans; HEV-3 and HEV-4 are zoonotic for which domestic and feral pigs are the main reservoirs. In most cases, the origin of autochthonous Hepatitis E cases in humans is unknown, but foodborne transmission has been clearly associated to sporadic cases and small clusters of infection linked to the consumption of contaminated pig liver sausages, raw deer meat, or undercooked wild boar meat. In Europe as well as in Italy, HEV-3 strains are widespread in pig farms and the within-herd prevalence varies from 10 to 100% depending on the study. The infection among animals is transmitted through the fecal oral route but it is not clear how long the virus can persist in the farm and the role of environmental as source of infection. The farm investigated was a farrow-to-finish herd consisting of 1000 breeders (site 1, breeding and nursery production stage) with growing pigs located in another premise (site 2, finisher production stage) in Northern Italy, sampled three times across 15 months. A total of 281 pool fecal samples were collected in 2017 (n=99), 2018 (n=142) and 2019 (n=40). Total viral RNA was extracted from fecal suspensions, and the HEV genome was detected by quantitative Real-Time RT-PCR (RT-qPCR).