Issue |
Vet. Res.
Volume 39, Number 5, September-October 2008
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Number of page(s) | 11 | |
DOI | https://doi.org/10.1051/vetres:2008017 | |
Published online | 27 March 2008 | |
How to cite this article | Vet. Res. (2008) 39:40 |
DOI: 10.1051/vetres:2008017
Estimation of hepatitis E virus transmission among pigs due to contact-exposure
Martijn Bouwknegt1, 2, Klaas Frankena2, Saskia A. Rutjes1, Gerard J. Wellenberg3, Ana Maria de Roda Husman1, Wim H.M. van der Poel3 and Mart C.M. de Jong2, 31 Laboratory for Zoonoses and Environmental Microbiology, Centre for Infectious Disease Control Netherlands, National Institute for Public Health and the Environment, Bilthoven, The Netherlands
2 Quantitative Veterinary Epidemiology Group, Wageningen Institute of Animal Sciences, Wageningen, The Netherlands
3 Animal Sciences Group of Wageningen UR, Department of Infectious Diseases, Lelystad, The Netherlands
Received 19 August 2007; accepted 19 March 2008; published online 27 March 2008
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 R0. In this study, R0 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.
Key words: hepatitis E virus / transmission / contact-exposure / reproduction ratio / pigs
Corresponding author: martijn.bouwknegt@rivm.nl
© INRA, EDP Sciences 2008