title: Influenza surveillance in Zambia, 2008-2009.
abstract: BACKGROUND
  Limited information exists about influenza viruses in Africa. We used data from a new sentinel surveillance system to investigate the seasonality and characteristics of influenza, including pandemic (pdm) influenza A H1N1, in Zambia.
  
  
  METHODS
  In June 2008, we established sentinel surveillance for influenza-like illness (ILI) and severe acute respiratory illness (SARI) at 4 healthcare facilities in Zambia. Nasopharyngeal and oropharyngeal swabs and structured questionnaires were collected from eligible patients and samples were tested by real-time reverse-transcription polymerase chain reaction for influenza virus types and subtypes.
  
  
  RESULTS
  From June 2008 to December 2009, we collected 1234 specimens, of which 334 (27%) were ILI, and 900 (63%) were SARI. Overall, 4% (57) of specimens were positive for influenza. The influenza detection rate in ILI and SARI cases was 5% (17/334) and 4% (40/900), respectively. Among all influenza cases, 54 (95%) were influenza A and 3 (5%) were influenza B. Of the influenza A viruses, 16 (30%) were A(H1N1)pdm09, 29 (54%) were seasonal A(H1N1), 6 (11%) were A(H3N2), and 4 (7%) were unsubtyped. The detection rate for A(H1N1)pdm09 cases was highest in persons aged 5-24 years (5/98; 5%), 25-44 years (4/78; 5%), and 45-64 years (1/17; 6%). Conversely, for seasonal influenza the detection rate was highest in children aged 1-4 years (18/294; 6%). Influenza virus circulation peaked during June-August in both years and A(H1N1)pdm09 occurred at the end of the influenza season in 2009.
  
  
  CONCLUSIONS
  Seasonal influenza virus infection was found to be associated with both mild and severe respiratory illness in Zambia. Future years of surveillance are necessary to better define the seasonality and epidemiology of influenza in the country.
authors.affiliation: Virology Laboratory,  University Teaching Hospital.
authors.forename: Andros
authors.initials: A
authors.lastname: Theo
authors.forename: Mazyanga
authors.initials: M
authors.lastname: Liwewe
authors.forename: Idah
authors.initials: I
authors.lastname: Ndumba
authors.forename: Zacharia
authors.initials: Z
authors.lastname: Mupila
authors.forename: Bushimbwa
authors.initials: B
authors.lastname: Tambatamba
authors.forename: Charles
authors.initials: C
authors.lastname: Mutemba
authors.forename: Somwe Wa
authors.initials: SW
authors.lastname: Somwe
authors.forename: Alywn
authors.initials: A
authors.lastname: Mwinga
authors.forename: Stefano
authors.initials: S
authors.lastname: Tempia
authors.forename: Mwaka
authors.initials: M
authors.lastname: Monze
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D004196:Disease Outbreaks; D005260:Female; D006801:Humans; D007223:Infant; D053118:Influenza A Virus, H1N1 Subtype / Q000145:classification / Q000302:isolation & purification; D009981:Influenza B virus / Q000145:classification / Q000302:isolation & purification; D007251:Influenza, Human / Q000453:epidemiology* / Q000821:virology; D008297:Male; D008875:Middle Aged; D058873:Pandemics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012621:Seasons; D018571:Sentinel Surveillance; D045169:Severe Acute Respiratory Syndrome / Q000453:epidemiology* / Q000821:virology; D055815:Young Adult; D015024:Zambia / Q000453:epidemiology