Saturday, 2 November 2013

Hepatitis E in humans, pigs and pork.


There have been more papers published recently about Hepatitis E in humans, pigs and both.

We started talking publicly about the human risks from Hepatitis E in pigs more than six years ago.

That puts British government veterinarians on the hotplate yet again. We know there have been a number of cases in Cornish pig farmers.

You can find twenty-seven articles on this blog about Hepatitis E, going back more than three years (use the search function on the page) and many on the newsgroup uk.business.agriculture (use Google Groups Search here).

PubMed abstract here


Vet Res. 2013 Oct 28;44(1):102. [Epub ahead of print]

Direct contact and environmental contaminations are responsible for HEV transmission in pigs.

Andraud M, Dumarest M, Cariolet R, Aylaj B, Barnaud E, Eono F, Pavio N, Rose N.

Abstract

Hepatitis E virus (HEV) can cause enterically-transmitted hepatitis in humans. The zoonotic nature of Hepatitis E infections has been established in industrialized areas and domestic pigs are considered as the main reservoir. The dynamics of transmission in pig herds therefore needs to be understood to reduce the prevalence of viremic pigs at slaughter and prevent contaminated pig products from entering the food chain.

An experimental trial was carried out to study the main characteristics of HEV transmission between orally inoculated pigs and naive animals. A mathematical model was used to investigate three transmission routes, namely direct contact between pigs and two environmental components to represent within-and between-group oro-fecal transmission. A large inter-individual variability was observed in response to infection with an average latent period lasting 6.9 days (5.8; 7.9) in inoculated animals and an average infectious period of 9.7 days (8.2; 11.2). Our results show that direct transmission alone, with a partial reproduction number of 1.41
(0.21; 3.02), can be considered as a factor of persistence of infection within a population. However, the quantity of virus present in the environment was found to play an essential role in the transmission process strongly influencing the probability of infection with a within pen transmission rate estimated to 2 . 10- 6g ge- 1d-1(1 . 10- 7; 7 . 10- 6). Between-pen environmental transmission occurred to a lesser extent (transmission rate: 7 . 10- 8g ge- 1d- 1(5 . 10- 9; 3 . 10- 7) but could further generate a within-group process.

The combination of these transmission routes could explain the persistence and high prevalence of HEV in pig populations.