title: Characterization of influenza activity based on virological surveillance of influenza-like illness in tropical Singapore, 2010-2014.
abstract: Singapore is situated in the tropics where the seasonality of influenza is not as well defined as that of temperate countries. We examined the circulation of influenza viruses in the community in terms of the characteristics of influenza activity. We reviewed laboratory-confirmed virological data collected between 2010 and 2014 under the national influenza surveillance programme. Influenza activity was measured by the proportion of specimens from outpatients with influenza-like illness tested positive for influenza virus based on 4-weekly moving interval. Seasonal epidemics occurred around the end of previous year or the beginning and middle of the year. Increases in influenza positivity were more pronounced when there was a change in the predominant circulating influenza virus type/subtype to influenza A(H3N2). Influenza epidemics lasted about 12 weeks on average, with longer duration when there was a change in the predominant influenza type/subtype and especially when it was associated with influenza A(H3N2). Continuous influenza surveillance is important as it could provide early warning of imminent surges in virus transmission, and allow for timely implementation of public health prevention and control interventions to minimize influenza-associated disease burden. J. Med. Virol. 88:2069-2077, 2016. © 2016 Wiley Periodicals, Inc.
authors.affiliation: Epidemiology and Disease Control Division, Ministry of Health, Singapore. ang_li_wei@moh.gov.sg.
authors.forename: Li Wei
authors.initials: LW
authors.lastname: Ang
authors.affiliation: Communicable Diseases Division, Ministry of Health, Singapore.
authors.forename: Wee Siong
authors.initials: WS
authors.lastname: Tien
authors.affiliation: Communicable Diseases Division, Ministry of Health, Singapore.
authors.forename: Raymond Tzer-Pin
authors.initials: RT
authors.lastname: Lin
authors.affiliation: Communicable Diseases Division, Ministry of Health, Singapore.
authors.forename: Lin
authors.initials: L
authors.lastname: Cui
authors.affiliation: Communicable Diseases Division, Ministry of Health, Singapore.
authors.forename: Jeffery
authors.initials: J
authors.lastname: Cutter
authors.affiliation: Epidemiology and Disease Control Division, Ministry of Health, Singapore.
authors.forename: Lyn
authors.initials: L
authors.lastname: James
authors.affiliation: Communicable Diseases Division, Ministry of Health, Singapore.|Saw Swee Hock School of Public Health, National University of Singapore, Singapore.
authors.forename: Kee Tai
authors.initials: KT
authors.lastname: Goh
mesh_terms: D058872:Epidemics / Q000517:prevention & control; D062665:Epidemiological Monitoring; D006801:Humans; D053122:Influenza A Virus, H3N2 Subtype / Q000276:immunology / Q000302:isolation & purification*; D009980:Influenza A virus / Q000276:immunology / Q000302:isolation & purification*; D009981:Influenza B virus / Q000276:immunology / Q000302:isolation & purification*; D007251:Influenza, Human / Q000453:epidemiology* / Q000517:prevention & control / Q000635:transmission / Q000821:virology; D036301:Qualitative Research; D012189:Retrospective Studies; D012621:Seasons; D012846:Singapore / Q000453:epidemiology; D013997:Time Factors; D014329:Tropical Climate; D014777:Virus Diseases / Q000453:epidemiology / Q000517:prevention & control / Q000821:virology
keywords: epidemics; influenza virus; seasonality; surveillance