Timing of Influenza A(H5N1) in Poultry and Humans and Seasonal Influenza Activity Worldwide, 2004–2013

• Main Authors: Lizette O. Durand, Patrick Glew, Diane Gross, Matthew R. Kasper, Susan C. Trock, Inkyu K. Kim, Joseph S. Bresee, Ruben O. Donis, Timothy M. Uyeki, Marc-Alain Widdowson, Eduardo Azziz-Baumgartner
• Format: Article
• Language: English
• Published: Centers for Disease Control and Prevention 2015-02-01
• Series: Emerging Infectious Diseases
• Subjects: H5N1; poultry; human; seasonal influenza; global; influenza
• Online Access: https://wwwnc.cdc.gov/eid/article/21/2/14-0877_article

Co-circulation of influenza A(H5N1) and seasonal influenza viruses among humans and animals could lead to co-infections, reassortment, and emergence of novel viruses with pandemic potential. We assessed the timing of subtype H5N1 outbreaks among poultry, human H5N1 cases, and human seasonal influenza in 8 countries that reported 97% of all human H5N1 cases and 90% of all poultry H5N1 outbreaks. In these countries, most outbreaks among poultry (7,001/11,331, 62%) and half of human cases (313/625, 50%) occurred during January–March. Human H5N1 cases occurred in 167 (45%) of 372 months during which outbreaks among poultry occurred, compared with 59 (10%) of 574 months that had no outbreaks among poultry. Human H5N1 cases also occurred in 59 (22%) of 267 months during seasonal influenza periods. To reduce risk for co-infection, surveillance and control of H5N1 should be enhanced during January–March, when H5N1 outbreaks typically occur and overlap with seasonal influenza virus circulation.