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Open Access Research article

Circulation of human influenza viruses and emergence of Oseltamivir-resistant A(H1N1) viruses in Cameroon, Central Africa

Richard Njouom1*, Serge A Sadeuh Mba1, Dominique Noah Noah2, Victoria Gregory3, Patrick Collins3, Pierre Cappy1, Alan Hay3 and Dominique Rousset1

Author Affiliations

1 Laboratory of Virology, Centre Pasteur of Cameroon, Yaounde, Cameroon

2 Department of Disease Control, Ministry of Health, Yaounde, Cameroon

3 WHO Collaborating Centre for Reference and Research on influenza, MRC National Institute for Medical Research, London, UK

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BMC Infectious Diseases 2010, 10:56  doi:10.1186/1471-2334-10-56

Published: 8 March 2010

Abstract

Background

While influenza surveillance has increased in most developing countries in the last few years, little influenza surveillance has been carried out in sub-Saharan Africa and no information is available in Central Africa. The objective of this study was to assess the prevalence of influenza viruses circulating in Yaounde, Cameroon and determine their antigenic and genetic characteristics.

Methods

Throat and/or nasal swabs were collected from November 2007 to October 2008 from outpatients with influenza-like illness (ILI) in Yaounde, Cameroon and analyzed by two different techniques: a one-step real time reverse transcription-polymerase chain reaction (RT-PCR) and virus isolation in MDCK cells. Typing and subtyping of virus isolates was performed by hemagglutination inhibition (HI), and viruses were sent to the WHO Collaborating Centre in London, UK for further characterization and analyses of antiviral resistance by enzyme inhibition assay and nucleotide sequencing.

Results

A total of 238 patients with ILI were sampled. During this period 70 (29%) samples were positive for influenza by RT-PCR, of which only 26 (11%) were positive by virus isolation. By HI assay, 20 of the 26 isolates were influenza type A (10 H3N2 and 10 H1N1) and 6 were influenza type B (2 B/Victoria/2/87 lineage and 4 B/Yagamata/16/88 lineage). Seven (70%) of the H1N1 isolates were shown to be resistant to oseltamivir due to a H275Y mutation.

Conclusions

This study confirmed the circulation of influenza A(H1N1), A(H3N2) and B viruses in the human population in Central Africa and describes the emergence of oseltamivir-resistant A(H1N1) viruses in Central Africa.