Secondary Household Transmission of 2009 Pandemic Influenza A (H1N1) Virus among an Urban and Rural Population in Kenya, 2009–2010

Details

• Alternative Title:
  PLoS One
• Personal Author:
  Kim, Clara Y. ; Breiman, Robert F. ; Cosmas, Leonard ; Audi, Allan ; Aura, Barrack ; Bigogo, Godfrey ; Njuguna, Henry ; Lebo, Emmaculate ; Waiboci, Lilian ; Njenga, M. Kariuki ; Feikin, Daniel R. ; Katz, Mark A.
• Description:
  Background
  
  In Kenya, >1,200 laboratory-confirmed 2009 pandemic influenza A (H1N1) (pH1N1) cases occurred since June 2009. We used population-based infectious disease surveillance (PBIDS) data to assess household transmission of pH1N1 in urban Nairobi (Kibera) and rural Lwak.
  
  Methods
  
  We defined a pH1N1 patient as laboratory-confirmed pH1N1 infection among PBIDS participants during August 1, 2009–February 5, 2010, in Kibera, or August 1, 2009–January 20, 2010, in Lwak, and a case household as a household with a laboratory-confirmed pH1N1 patient. Community interviewers visited PBIDS-participating households to inquire about illnesses among household members. We randomly selected 4 comparison households per case household matched by number of children aged <5. Comparison households had a household visit 10 days before or after the matched patient symptom onset date. We defined influenza-like illnesses (ILI) as self-reported cough or sore throat, and a self-reported fever ≤8 days after the pH1N1 patient's symptom onset in case households and ≤8 days before selected household visit in comparison households. We used the Cochran-Mantel-Haenszel test to compare proportions of ILIs among case and comparison households, and log binomial-model to compare that of Kibera and Lwak.
  
  Results
  
  Among household contacts of patients with confirmed pH1N1 in Kibera, 4.6% had ILI compared with 8.2% in Lwak (risk ratio [RR], 0.5; 95% confidence interval [CI], 0.3–0.9). Household contacts of patients were more likely to have ILIs than comparison-household members in both Kibera (RR, 1.8; 95% CI, 1.1–2.8) and Lwak (RR, 2.6; 95% CI, 1.6–4.3). Overall, ILI was not associated with patient age. However, ILI rates among household contacts were higher among children aged <5 years than persons aged ≥5 years in Lwak, but not Kibera.
  
  Conclusions
  
  Substantial pH1N1 household transmission occurred in urban and rural Kenya. Household transmission rates were higher in the rural area.
  
  
• Subjects:
  Family Characteristics Humans Influenza, Human Influenza A Virus, H1N1 Subtype Models, Statistical Odds Ratio Pandemics Population Surveillance Research Article Rural Population Urban Population

  More +
• Source:
  PLoS One. 2012; 7(6).
• Document Type:
  Journal Article
• Place as Subject:
  Kenya
• Volume:
  7
• Issue:
  6
• Collection(s):
  CDC Public Access
• Main Document Checksum:
  urn:sha256:5ef8f1e5320edb5e113fdc482cbc7b53ad0f57785462d830ed8fc2d454692509
• Download URL:
  https://stacks.cdc.gov/view/cdc/8200/cdc_8200_DS1.pdf
• File Type:
  [PDF - 237.09 KB ]