Detecting Spread of Avian Influenza A(H7N9) Virus Beyond China

• Published in: Emerging infectious diseases Vol. 21; no. 5; pp. 741 - 749
• Main Authors: Millman, Alexander J, Havers, Fiona, Iuliano, A Danielle, Davis, C Todd, Sar, Borann, Sovann, Ly, Chin, Savuth, Corwin, Andrew L, Vongphrachanh, Phengta, Douangngeun, Bounlom, Lindblade, Kim A, Chittaganpitch, Malinee, Kaewthong, Viriya, Kile, James C, Nguyen, Hien T, Pham, Dong V, Donis, Ruben O, Widdowson, Marc-Alain
• Format: Journal Article
• Language: English
• Published: United States U.S. National Center for Infectious Diseases 01.05.2015; Centers for Disease Control and Prevention
• Subjects: A(H5N1); A(H7N9); Animals; Asia, Southeastern - epidemiology; Avian influenza; Avian influenza viruses; China; China - epidemiology; Disease Outbreaks; Geography; Humans; Influenza; Influenza A Virus, H5N1 Subtype; Influenza A Virus, H7N9 Subtype; Influenza in Birds - epidemiology; Influenza in Birds - transmission; Influenza in Birds - virology; Influenza, Human - epidemiology; Influenza, Human - transmission; Influenza, Human - virology; Population Surveillance; Poultry; surveillance; viruses; Asia, Southeastern; China; Southeast Asia; Vietnam; Cambodia; Thailand; Laos; poultry; viruses; Cambodia; Thailand; respiratory infections; A(H7N9); Southeast Asia; Vietnam; A(H5N1); China; Influenza; surveillance; Laos
• ISSN: 1080-6040; 1080-6059
• DOI: 10.3201/eid2105.141756

During February 2013-March 2015, a total of 602 human cases of low pathogenic avian influenza A(H7N9) were reported; no autochthonous cases were reported outside mainland China. In contrast, since highly pathogenic avian influenza A(H5N1) reemerged during 2003 in China, 784 human cases in 16 countries and poultry outbreaks in 53 countries have been reported. Whether the absence of reported A(H7N9) outside mainland China represents lack of spread or lack of detection remains unclear. We compared epidemiologic and virologic features of A(H5N1) and A(H7N9) and used human and animal influenza surveillance data collected during April 2013-May 2014 from 4 Southeast Asia countries to assess the likelihood that A(H7N9) would have gone undetected during 2014. Surveillance in Vietnam and Cambodia detected human A(H5N1) cases; no A(H7N9) cases were detected in humans or poultry in Southeast Asia. Although we cannot rule out the possible spread of A(H7N9), substantial spread causing severe disease in humans is unlikely.