title: Estimation of transmission parameters of H5N1 avian influenza virus in chickens.
abstract: Despite considerable research efforts, little is yet known about key epidemiological parameters of H5N1 highly pathogenic influenza viruses in their avian hosts. Here we show how these parameters can be estimated using a limited number of birds in experimental transmission studies. Our quantitative estimates, based on Bayesian methods of inference, reveal that (i) the period of latency of H5N1 influenza virus in unvaccinated chickens is short (mean: 0.24 days; 95% credible interval: 0.099-0.48 days); (ii) the infectious period of H5N1 virus in unvaccinated chickens is approximately 2 days (mean: 2.1 days; 95%CI: 1.8-2.3 days); (iii) the reproduction number of H5N1 virus in unvaccinated chickens need not be high (mean: 1.6; 95%CI: 0.90-2.5), although the virus is expected to spread rapidly because it has a short generation interval in unvaccinated chickens (mean: 1.3 days; 95%CI: 1.0-1.5 days); and (iv) vaccination with genetically and antigenically distant H5N2 vaccines can effectively halt transmission. Simulations based on the estimated parameters indicate that herd immunity may be obtained if at least 80% of chickens in a flock are vaccinated. We discuss the implications for the control of H5N1 avian influenza virus in areas where it is endemic.
authors.affiliation: Faculty of Veterinary Medicine, Utrecht University, The Netherlands.
authors.forename: Annemarie
authors.initials: A
authors.lastname: Bouma
authors.forename: Ivo
authors.initials: I
authors.lastname: Claassen
authors.forename: Ketut
authors.initials: K
authors.lastname: Natih
authors.forename: Don
authors.initials: D
authors.lastname: Klinkenberg
authors.forename: Christl A
authors.initials: CA
authors.lastname: Donnelly
authors.forename: Guus
authors.initials: G
authors.lastname: Koch
authors.forename: Michiel
authors.initials: M
authors.lastname: van Boven
mesh_terms: D000818:Animals; D001499:Bayes Theorem; D002645:Chickens; D003198:Computer Simulation; D032521:Immunity, Herd; D053124:Influenza A Virus, H5N1 Subtype / Q000276:immunology / Q000472:pathogenicity*; D007252:Influenza Vaccines / Q000276:immunology*; D005585:Influenza in Birds / Q000453:epidemiology / Q000276:immunology / Q000635:transmission* / Q000821:virology; D014611:Vaccination / Q000662:veterinary*; D017735:Virus Latency
chemical_list: D007252:Influenza Vaccines