title: Characteristics of seasonal influenza A and B in Latin America: Influenza surveillance data from ten countries.
abstract: BACKGROUND
  The increased availability of influenza surveillance data in recent years justifies an actual and more complete overview of influenza epidemiology in Latin America. We compared the influenza surveillance systems and assessed the epidemiology of influenza A and B, including the spatio-temporal patterns of influenza epidemics, in ten countries and sub-national regions in Latin America.
  
  
  METHODS
  We aggregated the data by year and country and characteristics of eighty-two years were analysed. We calculated the median proportion of laboratory-confirmed influenza cases caused by each virus strain, and compared the timing and amplitude of the primary and secondary peaks between countries.
  
  
  RESULTS
  37,087 influenza cases were reported during 2004-2012. Influenza A and B accounted for a median of 79% and, respectively, 21% of cases in a year. The percentage of influenza A cases that were subtyped was 82.5%; for influenza B, 15.6% of cases were characterized. Influenza A and B were dominant in seventy-five (91%) and seven (9%) years, respectively. In half (51%) of the influenza A years, influenza A(H3N2) was dominant, followed by influenza A(H1N1)pdm2009 (41%) and pre-pandemic A(H1N1) (8%). The primary peak of influenza activity was in June-September in temperate climate countries, with little or no secondary peak. Tropical climate countries had smaller primary peaks taking place in different months and frequently detectable secondary peaks.
  
  
  CONCLUSIONS
  We found that good influenza surveillance data exists in Latin America, although improvements can still be made (e.g. a better characterization of influenza B specimens); that influenza B plays a considerable role in the seasonal influenza burden; and that there is substantial heterogeneity of spatio-temporal patterns of influenza epidemics. To improve the effectiveness of influenza control measures in Latin America, tropical climate countries may need to develop innovative prevention strategies specifically tailored to the spatio-temporal patterns of influenza in this region.
authors.affiliation: Netherlands Institute for Health Services Research (NIVEL), Utrecht, The Netherlands.
authors.forename: Saverio
authors.initials: S
authors.lastname: Caini
authors.affiliation: Fogarty International Center, National Institutes of Health, Bethesda, Maryland, United States of America.
authors.forename: Wladimir J
authors.initials: WJ
authors.lastname: Alonso
authors.affiliation: National Influenza Center, Ministry of Health, Managua, Nicaragua.
authors.forename: Angel
authors.initials: A
authors.lastname: Balmaseda
authors.affiliation: Instituto Nacional de Investigacion en Salud Publica (INSPI), Centro de Referencia Nacional de Influenza y Otros Virus Respiratorios, Guayaquil, Ecuador.
authors.forename: Alfredo
authors.initials: A
authors.lastname: Bruno
authors.affiliation: Seccion Virus Respiratorios, Instituto de Salud Publica de Chile, Santiago, Chile.
authors.forename: Patricia
authors.initials: P
authors.lastname: Bustos
authors.affiliation: National Influenza Center, Ministry of Health, Guatemala City, Guatemala.
authors.forename: Leticia
authors.initials: L
authors.lastname: Castillo
authors.affiliation: National Influenza Center, Ministry of Health, San Salvador, El Salvador.
authors.forename: Celina
authors.initials: C
authors.lastname: de Lozano
authors.affiliation: Instituto Nacional de Investigacion en Salud Publica (INSPI), Centro de Referencia Nacional de Influenza y Otros Virus Respiratorios, Guayaquil, Ecuador.
authors.forename: Doménica
authors.initials: D
authors.lastname: de Mora
authors.affiliation: Seccion Virus Respiratorios, Instituto de Salud Publica de Chile, Santiago, Chile.
authors.forename: Rodrigo A
authors.initials: RA
authors.lastname: Fasce
authors.affiliation: Ministry of Health, Federal District, Brazil.
authors.forename: Walquiria Aparecida
authors.initials: WA
authors.lastname: Ferreira de Almeida
authors.affiliation: Instituto Nacional de Enfermedades Respiratorias "Dr. Emilio Coni", ANLIS "C.Malbràn", Santa Fe, Argentina.
authors.forename: Gabriela F
authors.initials: GF
authors.lastname: Kusznierz
authors.affiliation: National Influenza Center, Ministry of Health, San José, Costa Rica.
authors.forename: Jenny
authors.initials: J
authors.lastname: Lara
authors.affiliation: National Influenza Center, Ministry of Health, Tegucigalpa, Honduras.
authors.forename: Maria Luisa
authors.initials: ML
authors.lastname: Matute
authors.affiliation: National Influenza Center, IC Gorgas, Panama City, Panama.
authors.forename: Brechla
authors.initials: B
authors.lastname: Moreno
authors.affiliation: Ministry of Health, Federal District, Brazil.
authors.forename: Claudio Maierovitch
authors.initials: CM
authors.lastname: Pessanha Henriques
authors.affiliation: Instituto Nacional de Enfermedades Respiratorias "Dr. Emilio Coni", ANLIS "C.Malbràn", Santa Fe, Argentina.
authors.forename: Juan Manuel
authors.initials: JM
authors.lastname: Rudi
authors.affiliation: Sanofi Pasteur, Lyon, France.
authors.forename: Clotilde
authors.initials: C
authors.lastname: El-Guerche Séblain
authors.affiliation: Netherlands Institute for Health Services Research (NIVEL), Utrecht, The Netherlands.|Department of General Practice and Elderly Care Medicine, EMGO Institute for Health Care Research VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: François
authors.initials: F
authors.lastname: Schellevis
authors.affiliation: Netherlands Institute for Health Services Research (NIVEL), Utrecht, The Netherlands.
authors.forename: John
authors.initials: J
authors.lastname: Paget
mesh_terms: D006801:Humans; D009980:Influenza A virus; D009981:Influenza B virus; D007251:Influenza, Human / Q000453:epidemiology* / Q000821:virology; D007843:Latin America; D011159:Population Surveillance; D012621:Seasons; D014329:Tropical Climate