Environmental Factors Influencing the Spread of the Highly Pathogenic Avian Influenza H5N1 Virus in wild birds in Europe
Yali Si, Faculty of Geo-Information Science and Earth Observation (ITC), University of Twente; Resource Ecology Group, Wageningen University; School of Resources and Environmental Science, Wuhan University
Tiejun Wang, Faculty of Geo-Information Science and Earth Observation (ITC), University of Twente
Andrew K. Skidmore, Faculty of Geo-Information Science and Earth Observation (ITC), University of Twente
Willem F. de Boer, Resource Ecology Group, Wageningen University
Lin Li, School of Resources and Environmental Science, Wuhan University
Herbert H.T. Prins, Resource Ecology Group, Wageningen University
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A large number of occurrences of the highly pathogenic avian influenza (HPAI) H5N1 virus in wild birds were reported in Europe. The relationship between the occurrence pattern and environmental factors has, however, not yet been explored. This research uses logistic regression to quantify the relationships between anthropogenic or physical environmental factors and HPAI H5N1 occurrences. Our results indicate that HPAI H5N1 occurrences are highly correlated with the following: the increased normalized difference vegetation index (NDVI) in December; intermediate NDVI in March; lower elevations; increased minimum temperatures in January; and reduced precipitation in January. A predictive risk map of HPAI H5N1 occurrences in wild birds in Europe was generated on the basis of five key environmental factors. Independent validation of the risk map showed the predictive model to be of high accuracy (79%). The analysis suggests that HPAI H5N1 occurrences in wild birds are strongly influenced by the availability of food resources and are facilitated by increased temperatures and reduced precipitation. We therefore deduced that HPAI H5N1 occurrences in wild birds in Europe are probably caused by contact with other wild birds and not by contact with domestic poultry. These findings are important considerations for the global surveillance of HPAI H5N1 occurrences in wild birds.
avian influenza; anthropogenic environmental factor; Europe; HPAI H5N1; physical environmental factor; risk mapping; wild birds
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