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. 2017 Mar 27;12(3):e0174592.
doi: 10.1371/journal.pone.0174592. eCollection 2017.

Characteristics of seasonal influenza A and B in Latin America: Influenza surveillance data from ten countries

Saverio Caini  1 , Wladimir J Alonso  2 , Angel Balmaseda  3 , Alfredo Bruno  4 , Patricia Bustos  5 , Leticia Castillo  6 , Celina de Lozano  7 , Doménica de Mora  4 , Rodrigo A Fasce  5 , Walquiria Aparecida Ferreira de Almeida  8 , Gabriela F Kusznierz  9 , Jenny Lara  10 , Maria Luisa Matute  11 , Brechla Moreno  12 , Claudio Maierovitch Pessanha Henriques  8 , Juan Manuel Rudi  9 , Clotilde El-Guerche Séblain  13 , François Schellevis  1   14 , John Paget  1 ; Global Influenza B Study group–Latin America
Affiliations

Characteristics of seasonal influenza A and B in Latin America: Influenza surveillance data from ten countries

Saverio Caini et al. PLoS One. .

Abstract

Introduction: 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.

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Conflict of interest statement

Competing Interests: Clotilde El-Guerche Séblain is an employee of Sanofi Pasteur. She helped define the study objectives, was involved in the discussion on the interpretation of the results, critically revised the manuscript and approved its final version. However, she had no access to the study database, did not conduct any statistical analysis, and had no power to decide what results should be published and in what form, nor to what journal submit the manuscript. Importantly, when reviewing the manuscript, her revisions concerned the epidemiological findings and not the public health conclusions. All the other authors declare they have no conflict of interests to disclose.

Figures

Fig 1
Fig 1. Countries and sub-national regions that were included in the analysis.
The Global Influenza B Study, Latin-American countries, 2003–2014. Dark Blue: Central America. Light Blue: Brazil. Yellow: remaining sites in South America.
Fig 2
Fig 2. Heat map of monthly influenza virus incidence patterns, 2003–2014, sorted by latitude.
The Global Influenza B Study, Latin-American countries, 2003–2014.
Fig 3
Fig 3. Timing and amplitude of primary (circles) and secondary (triangles) peak of influenza detection by site, against their latitudinal position.
The size corresponds to the amplitude of influenza seasonality. Dark Blue: Central America. Light Blue: Brazil. Yellow: remaining sites in South America.
See this image and copyright information in PMC

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