Estimation of Transmission Parameters of H5N1 Avian Influenza Virus in Chickens

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.

[1]  T. Uyeki,et al.  Epidemiology of cases of H5N1 virus infection in Indonesia, July 2005-June 2006. , 2007, The Journal of infectious diseases.

[2]  M. Nielen,et al.  Transmission of the highly pathogenic avian influenza virus H5N1 within flocks during the 2004 epidemic in Thailand. , 2007, The Journal of infectious diseases.

[3]  Chang-won Lee,et al.  Inactivated North American and European H5N2 avian influenza virus vaccines protect chickens from Asian H5N1 high pathogenicity avian influenza virus , 2006, Avian pathology : journal of the W.V.P.A.

[4]  M.C.M. de Jong,et al.  Transmission of pseudorabies virus within pig populations is independent of the size of the population , 1995 .

[5]  F. Ball.  A unified approach to the distribution of total size and total area under the trajectory of infectives in epidemic models , 1986, Advances in Applied Probability.

[6]  Min-Chul Kim,et al.  Highly Pathogenic Avian Influenza Virus (H5N1) in Domestic Poultry and Relationship with Migratory Birds, South Korea , 2008, Emerging infectious diseases.

[7]  James Truscott,et al.  Control of a highly pathogenic H5N1 avian influenza outbreak in the GB poultry flock , 2007, Proceedings of the Royal Society B: Biological Sciences.

[8]  M. van Boven,et al.  Variable effect of vaccination against highly pathogenic avian influenza (H7N7) virus on disease and transmission in pheasants and teals. , 2007, Vaccine.

[9]  Armin R W Elbers,et al.  Estimating the day of highly pathogenic avian influenza (H7N7) virus introduction into a poultry flock based on mortality data. , 2007, Veterinary research.

[10]  D. Alexander.  Summary of Avian Influenza Activity in Europe, Asia, Africa, and Australasia, 2002–2006 , 2007, Avian diseases.

[11]  Marius Gilbert,et al.  Highly Pathogenic Avian Influenza H5N1, Thailand, 2004 , 2005, Emerging infectious diseases.

[12]  G. Koch,et al.  Within-Flock Mortality During the High-Pathogenicity Avian Influenza (H7N7) Epidemic in the Netherlands in 2003: Implications for an Early Detection System , 2007, Avian diseases.

[13]  Armin Elbers,et al.  Risk Maps for the Spread of Highly Pathogenic Avian Influenza in Poultry , 2007, PLoS Comput. Biol..

[14]  M. Begon,et al.  A clarification of transmission terms in host-microparasite models: numbers, densities and areas , 2002, Epidemiology and Infection.

[15]  G. Roberts,et al.  Bayesian inference for partially observed stochastic epidemics , 1999 .

[16]  George Streftaris,et al.  Bayesian analysis of experimental epidemics of foot–and–mouth disease , 2004, Proceedings of the Royal Society of London. Series B: Biological Sciences.

[17]  J. L. Montagne,et al.  Emerging infectious diseases. , 1994, The Journal of infectious diseases.

[18]  M. Gilbert,et al.  Mapping H5N1 highly pathogenic avian influenza risk in Southeast Asia , 2008, Proceedings of the National Academy of Sciences.

[19]  N. Savill,et al.  Detection of mortality clusters associated with highly pathogenic avian influenza in poultry: a theoretical analysis , 2008, Journal of The Royal Society Interface.

[20]  D. Suarez,et al.  Highly Pathogenic Avian Influenza , 2015, Radiology of Infectious Diseases: Volume 1.

[21]  Michael Höhle,et al.  Inference in disease transmission experiments by using stochastic epidemic models , 2005 .

[22]  Christl A. Donnelly,et al.  Detecting Emerging Transmissibility of Avian Influenza Virus in Human Households , 2007, PLoS Comput. Biol..

[23]  M C M de Jong,et al.  Quantification of the effect of vaccination on transmission of avian influenza (H7N7) in chickens. , 2005, Proceedings of the National Academy of Sciences of the United States of America.

[24]  A. Osterhaus,et al.  Avian Flu: Multiple introductions of H5N1 in Nigeria , 2006, Nature.

[25]  Peter Green,et al.  Markov chain Monte Carlo in Practice , 1996 .

[26]  N. Ferguson,et al.  Time lines of infection and disease in human influenza: a review of volunteer challenge studies. , 2008, American journal of epidemiology.

[27]  Marius Gilbert,et al.  Highly Pathogenic Avian Influenza H 5 N 1 , Thailand , 2004 , 2005 .

[28]  M. Lipsitch,et al.  How generation intervals shape the relationship between growth rates and reproductive numbers , 2007, Proceedings of the Royal Society B: Biological Sciences.

[29]  M. Keeling,et al.  Silent spread of H5N1 in vaccinated poultry , 2006, Nature.

[30]  O. Diekmann.  Mathematical Epidemiology of Infectious Diseases , 1996 .

[31]  M. van Boven,et al.  Transmission of highly pathogenic avian influenza H5N1 virus in Pekin ducks is significantly reduced by a genetically distant H5N2 vaccine. , 2008, Virology.

[32]  Vanessa K. Wilson,et al.  HIGHLY PATHOGENIC AVIAN INFLUENZA (H5N1) IN , 2005 .

[33]  I. Brown.  Summary of Avian Influenza Activity in Europe, Asia, and Africa, 2006–2009 , 2010, Avian diseases.

[34]  D. Kapczynski,et al.  Vaccines, Vaccination, and Immunology for Avian Influenza Viruses in Poultry , 2009 .

[35]  R. Webster,et al.  A pandemic warning? , 1997, Nature.

[36]  T. Mettenleiter,et al.  Protective efficacy of several vaccines against highly pathogenic H5N1 avian influenza virus under experimental conditions. , 2008, Vaccine.

[37]  R. Webster,et al.  Are We Ready for Pandemic Influenza? , 2003, Science.

[38]  Gavin J. Gibson,et al.  Bayesian inference for stochastic epidemics in closed populations , 2004 .

[39]  G. Koch,et al.  Performance of clinical signs in poultry for the detection of outbreaks during the avian influenza A (H7N7) epidemic in The Netherlands in 2003 , 2005, Avian pathology : journal of the W.V.P.A.

[40]  M. D. de Jong,et al.  Design and analysis of small-scale transmission experiments with animals , 2006, Epidemiology and Infection.

[41]  Pejman Rohani,et al.  Appropriate Models for the Management of Infectious Diseases , 2005, PLoS medicine.

[42]  Y. Guan,et al.  Vaccination of chickens against H5N1 avian influenza in the face of an outbreak interrupts virus transmission , 2004, Avian pathology : journal of the W.V.P.A.