title: Estimation of hepatitis E virus transmission among pigs due to contact-exposure.
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.
authors: Laboratory for Zoonoses and Environmental Microbiology, Centre for Infectious Disease Control Netherlands, National Institute for Public Health and the Environment, Bilthoven, The Netherlands. martijn.bouwknegt@rivm.nl
authors: Martijn
authors: M
authors: Bouwknegt
authors: Klaas
authors: K
authors: Frankena
authors: Saskia A
authors: SA
authors: Rutjes
authors: Gerard J
authors: GJ
authors: Wellenberg
authors: Ana Maria
authors: AM
authors: de Roda Husman
authors: Wim H M
authors: WH
authors: van der Poel
authors: Mart C M
authors: MC
authors: de Jong
mesh_terms: D000818:Animals; D016751:Hepatitis E / Q000635:transmission / Q000662:veterinary*; D016752:Hepatitis E virus; D013552:Swine; D013553:Swine Diseases / Q000635:transmission* / Q000821:virology; D013997:Time Factors