Author Affiliations: National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Md.
Although most experts believe another influenza pandemic will occur, it is difficult to predict when or where it will appear or how severe it will be. Neither is there agreement about the subtype of the next pandemic influenza virus. However, the continuing spread of H5N1 highly pathogenic avian influenza A (HPAI) among poultry on several continents, associated with an increasing number of severe and fatal human infections, has raised the pandemic stakes.1 Genetically and antigenically divergent H5N1 HPAI strains appeared in 1997 and have been spreading globally since 2003.2,3 To date, epizootics in approximately 60 countries have caused a reported 291 human cases with 172 deaths.4
Taubenberger JK, Morens DM, Fauci AS. The Next Influenza PandemicCan It Be Predicted?. JAMA. 2007;297(18):2025-2027. doi:10.1001/jama.297.18.2025