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. 2017 Dec 4;17(1):745.
doi: 10.1186/s12879-017-2839-1.

Epidemiology of influenza in West Africa after the 2009 influenza A(H1N1) pandemic, 2010-2012

Ndahwouh Talla Nzussouo  1   2   3 , Jazmin Duque  4   5 , Adebayo Abel Adedeji  6 , Daouda Coulibaly  7 , Samba Sow  8 , Zekiba Tarnagda  9 , Issaka Maman  10 , Adamou Lagare  11 , Sonia Makaya  12 , Mohamed Brahim Elkory  13 , Herve Kadjo Adje  14 , Paul Alhassan Shilo  6 , Boubou Tamboura  8 , Assana Cisse  9 , Kossi Badziklou  10 , Halima Boubacar Maïnassara  11 , Ahmed Ould Bara  13 , Adama Mamby Keita  8 , Thelma Williams  4 , Ann Moen  4 , Marc-Alain Widdowson  4 , Meredith McMorrow  4   15
Affiliations

Epidemiology of influenza in West Africa after the 2009 influenza A(H1N1) pandemic, 2010-2012

Ndahwouh Talla Nzussouo et al. BMC Infect Dis. .

Abstract

Background: Over the last decade, capacity for influenza surveillance and research in West Africa has strengthened. Data from these surveillance systems showed influenza A(H1N1)pdm09 circulated in West Africa later than in other regions of the continent.

Methods: We contacted 11 West African countries to collect information about their influenza surveillance systems (number of sites, type of surveillance, sampling strategy, populations sampled, case definitions used, number of specimens collected and number of specimens positive for influenza viruses) for the time period January 2010 through December 2012.

Results: Of the 11 countries contacted, 8 responded: Burkina Faso, Cote d'Ivoire, Mali, Mauritania, Niger, Nigeria, Sierra Leone and Togo. Countries used standard World Health Organization (WHO) case definitions for influenza-like illness (ILI) and severe acute respiratory illness (SARI) or slight variations thereof. There were 70 surveillance sites: 26 SARI and 44 ILI. Seven countries conducted SARI surveillance and collected 3114 specimens of which 209 (7%) were positive for influenza viruses. Among influenza-positive SARI patients, 132 (63%) were influenza A [68 influenza A(H1N1)pdm09, 64 influenza A(H3N2)] and 77 (37%) were influenza B. All eight countries conducted ILI surveillance and collected 20,375 specimens, of which 2278 (11%) were positive for influenza viruses. Among influenza-positive ILI patients, 1431 (63%) were influenza A [820 influenza A(H1N1)pdm09, 611 influenza A(H3N2)] and 847 (37%) were influenza B. A majority of SARI and ILI case-patients who tested positive for influenza (72% SARI and 59% ILI) were children aged 0-4 years, as were a majority of those enrolled in surveillance. The seasonality of influenza and the predominant influenza type or subtype varied by country and year.

Conclusions: Influenza A(H1N1)pdm09 continued to circulate in West Africa along with influenza A(H3N2) and influenza B during 2010-2012. Although ILI surveillance systems produced a robust number of samples during the study period, more could be done to strengthen surveillance among hospitalized SARI case-patients. Surveillance systems captured young children but lacked data on adults and the elderly. More data on risk groups for severe influenza in West Africa are needed to help shape influenza prevention and clinical management policies and guidelines.

Keywords: Epidemiology; Influenza; West Africa.

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Conflict of interest statement

Ethics approval and consent to participate

Verbal consent (or parent/guardian consent for children) of all human participants included in the study was provided prior to participation. We invited Ministries of Health, influenza reference laboratories and/or WHO NICs to participate in this study. Participation in this study was voluntary and in-country representatives shared their data willingly. Ethics approval was not required to access these data.

Consent for publication

All authors provided their consent for publication.

Competing interests

All authors are unanimous in declaring that there are no competing interests.

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Figures

Fig. 1
Fig. 1
Number of influenza-like illness (ILI) and severe acute respiratory illness (SARI) cases tested and proportion positive for influenza by age group, West Africa, 2010–2012
Fig. 2
Fig. 2
Summary of influenza virus circulation by month in 8 West African countries, 2010–2012
See this image and copyright information in PMC

References

    1. World Health Organization (WHO). Fact sheet 211: influenza (seasonal) [updated April, 2009 October 25, 2013]. Available from: http://www.who.int/mediacentre/factsheets/fs211/en/
    1. Lafond KE, Nair H, Rasooly MH, Valente F, Booy R, et al. Global role and burden of influenza in pediatric respiratory hospitalizations, 1982–2012: a systematic analysis. PLoS Med. 2016;13(3):e1001977. doi: 10.1371/journal.pmed.1001977. - DOI - PMC - PubMed
    1. Mark A. Katz, Barry D. Schoub, Jean Michel Heraud, Robert F. Breiman, M. Kariuki Njenga, and Marc-Alain Widdowson. Influenza in Africa: Uncovering the Epidemiology of a Long-Overlooked Disease. JID: 206 (Suppl 1). S1-S4. - PubMed
    1. World Health Organization, National Influenza Centers (WHO/NICs) http://www.who.int/influenza/gisrs_laboratory/national_influenza_centres...(Last Update: 2016).
    1. Radin JM, Katz MA, Tempia S, Nzussouo NT, Davis R, Duque J, et al. Influenza Surveillance in 15 Countries in Africa, 2006–2010. JID. 2012;206(Suppl 1):S14–S21. doi: 10.1093/infdis/jis606. - DOI - PubMed