Estimation of hepatitis E virus transmission among pigs due to contact-exposure

Vet Res. 2008 Sep-Oct;39(5):40. doi: 10.1051/vetres:2008017. Epub 2008 Mar 27.

Abstract

Locally acquired hepatitis E in humans from industrialized countries has been repeatedly suggested to originate from pigs. Pigs may serve as a reservoir of hepatitis E virus (HEV) for humans when a typical infected pig causes on average more than one newly infected pig, a property that is expressed by the basic reproduction ratio R(0). In this study, R(0) for HEV transmission among pigs was estimated from chains of one-to-one transmission experiments in two blocks of five chains each. Per chain, susceptible first-generation contact pigs were contact-exposed to intravenously inoculated pigs, subsequently susceptible second-generation contact pigs were contact-exposed to infected first-generation contact pigs, and lastly, susceptible third-generation contact pigs were contact-exposed to infected second-generation contact pigs. Thus, in the second and third link of the chain, HEV-transmission due to contact with a contact-infected pig was observed. Transmission of HEV was monitored by reverse transcriptase polymerase chain reaction (RT-PCR) on individual faecal samples taken every two/three days. For susceptible pigs, the average period between exposure to an infectious pig and HEV excretion was six days (standard deviation: 4). The length of HEV-excretion (i.e. infectious period) was estimated at 49 days (95% confidence interval (CI): 17-141) for block 1 and 13 days (95% CI: 11-17) for block 2. The R0 for contact-exposure was estimated to be 8.8 (95% CI: 4-19), showing the potential of HEV to cause epidemics in populations of pigs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Hepatitis E / transmission
  • Hepatitis E / veterinary*
  • Hepatitis E virus*
  • Swine
  • Swine Diseases / transmission*
  • Swine Diseases / virology
  • Time Factors