Circulation of human influenza viruses and emergence of Oseltamivir-resistant A(H1N1) viruses in Cameroon, Central Africa.
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.
Njouom
Richard
R
Laboratory of Virology, Centre Pasteur of Cameroon, Yaounde, Cameroon. njouom@pasteur-yaounde.org
Mba
Serge A Sadeuh
SA
Noah
Dominique Noah
DN
Gregory
Victoria
V
Collins
Patrick
P
Cappy
Pierre
P
Hay
Alan
A
Rousset
Dominique
D
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019943:Amino Acid Substitution / Q000235:genetics; D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology*; D002163:Cameroon / Q000453:epidemiology; D002460:Cell Line; D002648:Child; D002675:Child, Preschool; D004285:Dogs; D024882:Drug Resistance, Viral; D005260:Female; D006385:Hemagglutination Inhibition Tests; D006801:Humans; D007223:Infant; D007251:Influenza, Human / Q000453:epidemiology* / Q000821:virology*; D008297:Male; D008875:Middle Aged; D009666:Nose / Q000821:virology; D009975:Orthomyxoviridae / Q000145:classification* / Q000187:drug effects / Q000254:growth & development / Q000302:isolation & purification*; D053139:Oseltamivir / Q000494:pharmacology*; D010614:Pharynx / Q000821:virology; D015995:Prevalence; D012367:RNA, Viral / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D055815:Young Adult
D000998:Antiviral Agents; D012367:RNA, Viral; D053139:Oseltamivir