Effect of Species Interaction on the Outcome of a Highly Pathogenic Avian Influenza H5N1 Epizootic

Abstract

The heterogeneity in response to the H5N1 infection of three different species of waterfowl (Mute Swan, Common Pochard, Mallard), which were affected during the 2006 outbreak of highly pathogenic avian influenza in France, was suggested as the underlying reason for the small size of the outbreak. Through stochastic simulations of compartmental epidemiologic models that take into account both the individual behaviour of each of the three bird species and the interactions between them, the effect of host heterogeneity on the characteristics of the outbreak was analysed. Species diversity was found to induce either a decrease or an increase of the outbreak severity, depending on the mixing rates between the species and on the species to which the initially infected individual belonged to. It is found that an initially infected Mute Swan could generate major outbreaks, whereas Common Pochards and Mallards induce outbreaks of rather moderate sizes.