Background: The emerging highly pathogenic avian influenza strain H5N1 ("HPAI-H5N1") has
spread broadly in the past decade, and is now the focus of considerable concern. We tested the
hypothesis that spatial distributions of HPAI-H5N1 cases are related consistently and predictably
to coarse-scale environmental features in the Middle East and northeastern Africa.
We used ecological niche models to relate virus occurrences to 8 km resolution digital data layers
summarizing parameters of monthly surface reflectance and landform. Predictive challenges
included a variety of spatial stratification schemes in which models were challenged to predict case
distributions in broadly unsampled areas.
Results: In almost all tests, HPAI-H5N1 cases were indeed occurring under predictable sets of
environmental conditions, generally predicted absent from areas with low NDVI values and minimal
seasonal variation, and present in areas with a broad range of and appreciable seasonal variation in
NDVI values. Although we documented significant predictive ability of our models, even between
our study region and West Africa, case occurrences in the Arabian Peninsula appear to follow a
distinct environmental regime.
Conclusion: Overall, we documented a variable environmental "fingerprint" for areas suitable for
Williams, R.A.J. and Peterson, A.T. Ecology and geography of avian influenza (HPAI H5N1) transmission in the Middle East and northeastern Africa. International Journal of Health Geographics 2009, 8:47. http://dx.doi.org/10.1186/1476-072X-8-47