Phylogeography of influenza A H5N1 clade 188.8.131.52 in Egypt
1 Department of Biomedical Informatics, Arizona State University, 13212 E Shea Blvd, Samuel C Johnson Bldg, Scottsdale, AZ 85259, USA
2 Center for Environmental Security, Biodesign Institute and Security & Defense Systems Initiative, Arizona State University, Tempe, AZ, USA
3 Food and Agriculture Organization of the United Nations (FAO), Cairo, Egypt
4 Yale Occupational and Environmental Medicine Program, Yale University, New Haven, CT, USA
5 Department of Biostatistics, Yale School of Public health, Yale University, New Haven, CT, USA
6 Center for Clinical and Translational Science, Department of Microbiology & Molecular Genetics, University of Vermont, Burlington, VT, USA
7 Department of Computer Science, University of Vermont, Burlington, VT, USA
BMC Genomics 2013, 14:871 doi:10.1186/1471-2164-14-871Published: 10 December 2013
Influenza A H5N1 has killed millions of birds and raises serious public health concern because of its potential to spread to humans and cause a global pandemic. While the early focus was in Asia, recent evidence suggests that Egypt is a new epicenter for the disease. This includes characterization of a variant clade 184.108.40.206, which has been found almost exclusively in Egypt.
We analyzed 226 HA and 92 NA sequences with an emphasis on the H5N1 220.127.116.11 strains in Egypt using a Bayesian discrete phylogeography approach. This allowed modeling of virus dispersion between Egyptian governorates including the most likely origin.
Phylogeography models of hemagglutinin (HA) and neuraminidase (NA) suggest Ash Sharqiyah as the origin of virus spread, however the support is weak based on Kullback–Leibler values of 0.09 for HA and 0.01 for NA. Association Index (AI) values and Parsimony Scores (PS) were significant (p-value < 0.05), indicating that dispersion of H5N1 in Egypt was geographically structured. In addition, the Ash Sharqiyah to Al Gharbiyah and Al Fayyum to Al Qalyubiyah routes had the strongest statistical support.
We found that the majority of routes with strong statistical support were in the heavily populated Delta region. In particular, the Al Qalyubiyah governorate appears to represent a popular location for virus transition as it represented a large portion of branches in both trees. However, there remains uncertainty about virus dispersion to and from this location and thus more research needs to be conducted in order to examine this.
Phylogeography can highlight the drivers of H5N1 emergence and spread. This knowledge can be used to target public health efforts to reduce morbidity and mortality. For Egypt, future work should focus on using data about vaccination and live bird markets in phylogeography models to study their impact on H5N1 diffusion within the country.