Ecological factors driving avian influenza virus dynamics in Spanish wetland ecosystems

Abstract

[Objectives]: There is currently limited scientific information about the basic epidemiology of avian influenza viruses (AIV) in wild birds in natural ecosystems, including the role of the environment itself and the effect of bird population ecology on transmission and persistence of AIV. The aim of this work was to study the contribution of environmental and host factors in the occurrence of the low pathogenic AIV (LPAIV) in Spanish wetlands under field conditions. [Methods]: For this purpose five different Spanish wetlands were studied during two consecutive years. Fresh faeces and water were periodically collected for viral detection, and the association of LPAIV prevalence with climatic conditions, vegetation, physical properties of surface water and density and diversity of wild birds of the wetlands was assessed. [Results]: Mean LPAIV prevalence detected in fresh faeces was 1.7%±0.4, with significant temporal and spatial variation. Using variation partitioning procedures it could be concluded that the combination of space and time variables (locality, year and season), independently to other factors, explained the largest proportion of the variation (36.8%), followed by the meteorological factor (21.5%), and finally the combined effect of vegetation structure and wild bird community data, accounting for 21% of the variation. [Conclusion]: The results obtained are useful to generate hypotheses about ecological factors that may be associated with a higher occurrence of LPAIV in wetlands. This work may contribute to identify more efficient strategies of surveillance that target hotspots thus favouring early detection of AIV.