Global Patterns of Influenza A Virus in Wild Birds
Björn Olsen1,2,
Vincent J. Munster3,
Anders Wallensten4,5,
Jonas Waldenström6,
Albert D. M. E. Osterhaus3 and
Ron A. M. Fouchier3*
1 Department of Infectious Diseases, Umeå University, SE-90187 Umeå, Sweden.
2 Section for Zoonotic Ecology and Epidemiology, Department of Biology and Environmental Science, University of Kalmar, SE-39182 Kalmar, Sweden.
3 Department of Virology, Erasmus Medical Center, Rotterdam, Netherlands.
4 Smedby Health Center, Kalmar County Council, SE-39471 Kalmar, Sweden.
5 Division of Virology, Department of Molecular and Clinical Medicine (IMK) Faculty of Health Sciences, Linköping University, SE-581 85 Linköping, Sweden.
6 Department of Animal Ecology, Lund University, SE-22362 Lund, Sweden.
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Fig. 1. Migratory flyways of wild bird populations. A world map with the main general migratory flyways of wild bird populations is shown (adapted from information collected and analyzed by Wetlands International). (A) Black dots indicate the locations of historical and current influenza virus surveillance sites from which data have been used in this manuscript. These global migration flyways are simplifications, and there are situations where populations behave differently from the common patterns. Migration patterns of Mallard (Anas platyrhynchos) (B) and Garganey (Anas querquedula) in Eurasia and Africa and Blue-winged Teal (Anas discors) in the Americas (C) (right and left parts of the map, respectively) are provided. Yellow color indicates breeding areas in which species are absent during winter, green indicates areas in which species are present around the year, and blue indicates areas in which species are only present in winter and do not breed. Arrows indicate the seasonal migration patterns.
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Fig. 2. Phylogenetic tree for the matrix gene of influenza A viruses from a variety of hosts. Nucleotide sequences were selected from public databases and aligned, after which a maximum likelihood tree was generated using influenza virus A/Equine/Prague/57 (H7N7) as outgroup. Sequences were selected from each host to reflect the longest possible time frame and variation in locations of virus isolation. The avian influenza viruses are divided in an American lineage (pink) and a Eurasian lineage (yellow), and there are no clear patterns of host, temporal, or spatial correlation within these lineages. In contrast, the human influenza A virus lineage (light blue), the Eurasian swine lineage (purple), and the HPAI H5N1 lineage (orange) display clear temporal patterns of virus evolution.
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