title: Impact of influenza A(H1N1)pdm09 virus on circulation dynamics of seasonal influenza strains in Kenya.
abstract: We describe virus variations from patients with influenza-like illness before and after the appearance of influenza A(H1N1)pdm09 in Kenya during January 2008-July 2011. A total of 11,592 nasopharyngeal swabs were collected from consenting patients. Seasonal influenza B, A/H1N1, A/H3N2, A/H5N1, and influenza A(H1N1)pdm09 viruses were detected by real-time reverse transcription-polymerase chain reaction. Of patients enrolled, 2073 (17.9%) had influenza. A total of 1,524 (73.4%) of 2,073 samples were positive for influenza A virus and 549 (26.6%) were positive for influenza B virus. Influenza B virus predominated in 2008 and seasonal A(H1N1) virus predominated in the first half of 2009. Influenza A(H1N1)pdm09 virus predominated in the second half of 2009. Influenza A/H3N2 virus predominated in 2010, and co-circulation of influenza A(H1N1)pdm09 virus and influenza B virus predominated the first half of 2011. The reduction and displacement of seasonal A(H1N1) virus was the most obvious effect of the arrival of influenza A(H1N1)pdm09 virus. The decision of the World Health Organization to replace seasonal A(H1N1) virus with the pandemic virus strain for the southern hemisphere vaccine was appropriate for Kenya.
authors: U.S. Army Medical Research Unit, Kenya, Nairobi, Kenya. janet.majanja@usamru-k.org
authors: Janet
authors: J
authors: Majanja
authors: Rose N
authors: RN
authors: Njoroge
authors: Rachel
authors: R
authors: Achilla
authors: Eyako K
authors: EK
authors: Wurapa
authors: Meshack
authors: M
authors: Wadegu
authors: Silvanos
authors: S
authors: Mukunzi
authors: Josephat
authors: J
authors: Mwangi
authors: James
authors: J
authors: Njiri
authors: George
authors: G
authors: Gachara
authors: Wallace
authors: W
authors: Bulimo
mesh_terms: D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000235:genetics / Q000302:isolation & purification*; D053122:Influenza A Virus, H3N2 Subtype / Q000235:genetics / Q000302:isolation & purification; D009981:Influenza B virus / Q000235:genetics / Q000302:isolation & purification; D007251:Influenza, Human / Q000453:epidemiology* / Q000821:virology*; D007630:Kenya / Q000453:epidemiology; D009305:Nasopharynx / Q000821:virology; D058873:Pandemics; D012367:RNA, Viral / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012621:Seasons
chemical_list: D012367:RNA, Viral