title: Modelling the impact of co-circulating low pathogenic avian influenza viruses on epidemics of highly pathogenic avian influenza in poultry.
abstract: It is well known that highly pathogenic avian influenza (HPAI) viruses emerge through mutation of precursor low pathogenic avian influenza (LPAI) viruses in domestic poultry populations. The potential for immunological cross-protection between these pathogenic variants is recognised but the epidemiological impact during co-circulation is not well understood. Here we use mathematical models to investigate whether altered flock infection parameters consequent to primary LPAI infections can impact on the spread of HPAI at the population level. First we used mechanistic models reflecting the co-circulatory dynamics of LPAI and HPAI within a single commercial poultry flock. We found that primary infections with LPAI led to HPAI prevalence being maximised under a scenario of high but partial cross-protection. We then tested the population impact in spatially-explicit simulations motivated by a major avian influenza A(H7N1) epidemic that afflicted the Italian poultry industry in 1999-2001. We found that partial cross-protection can lead to a prolongation of HPAI epidemic duration. Our findings have implications for the control of HPAI in poultry particularly for settings in which LPAI and HPAI frequently co-circulate.
authors: Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.
authors: Sema
authors: S
authors: Nickbakhsh
authors: Institute of Evolutionary Biology, University of Edinburgh, EH9 3FL, UK; Centre for Immunity, Infection and Evolution, University of Edinburgh, Edinburgh EH9 3FL, UK.
authors: Matthew D
authors: MD
authors: Hall
authors: MRC Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London W2 1PG, UK.
authors: Ilaria
authors: I
authors: Dorigatti
authors: Institute of Evolutionary Biology, University of Edinburgh, EH9 3FL, UK; Centre for Immunity, Infection and Evolution, University of Edinburgh, Edinburgh EH9 3FL, UK.
authors: Samantha J
authors: SJ
authors: Lycett
authors: Istituto Zooprofilattico Sperimentale delle Venezie, Italy.
authors: Paolo
authors: P
authors: Mulatti
authors: Istituto Zooprofilattico Sperimentale delle Venezie, Italy.
authors: Isabella
authors: I
authors: Monne
authors: Istituto Zooprofilattico Sperimentale delle Venezie, Italy.
authors: Alice
authors: A
authors: Fusaro
authors: Institute of Evolutionary Biology, University of Edinburgh, EH9 3FL, UK; Centre for Immunity, Infection and Evolution, University of Edinburgh, Edinburgh EH9 3FL, UK.
authors: Mark E J
authors: MEJ
authors: Woolhouse
authors: Institute of Evolutionary Biology, University of Edinburgh, EH9 3FL, UK; Centre for Immunity, Infection and Evolution, University of Edinburgh, Edinburgh EH9 3FL, UK; Fogarty International Center, National Institutes of Health, Bethesda, MD 20892-2220, USA.
authors: Andrew
authors: A
authors: Rambaut
authors: Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, UK. Electronic address: rowland.kao@glasgow.ac.uk.
authors: Rowland R
authors: RR
authors: Kao
mesh_terms: D000818:Animals; D006801:Humans; D057916:Influenza A Virus, H7N1 Subtype / Q000472:pathogenicity*; D009980:Influenza A virus; D005585:Influenza in Birds / Q000453:epidemiology*; D007558:Italy / Q000453:epidemiology; D008962:Models, Theoretical; D011200:Poultry
keywords: Cross-protection; Epidemiology; Interference; Mathematical models; Poultry