title: Estimation of the national disease burden of influenza-associated severe acute respiratory illness in Kenya and Guatemala: a novel methodology.
abstract: BACKGROUND
  Knowing the national disease burden of severe influenza in low-income countries can inform policy decisions around influenza treatment and prevention. We present a novel methodology using locally generated data for estimating this burden.
  
  
  RESULTS
  This method begins with calculating the hospitalized severe acute respiratory illness (SARI) incidence for children <5 years old and persons ≥5 years old from population-based surveillance in one province. This base rate of SARI is then adjusted for each province based on the prevalence of risk factors and healthcare-seeking behavior. The percentage of SARI with influenza virus detected is determined from provincial-level sentinel surveillance and applied to the adjusted provincial rates of hospitalized SARI. Healthcare-seeking data from healthcare utilization surveys is used to estimate non-hospitalized influenza-associated SARI. Rates of hospitalized and non-hospitalized influenza-associated SARI are applied to census data to calculate the national number of cases. The method was field-tested in Kenya, and validated in Guatemala, using data from August 2009-July 2011. In Kenya (2009 population 38.6 million persons), the annual number of hospitalized influenza-associated SARI cases ranged from 17,129-27,659 for children <5 years old (2.9-4.7 per 1,000 persons) and 6,882-7,836 for persons ≥5 years old (0.21-0.24 per 1,000 persons), depending on year and base rate used. In Guatemala (2011 population 14.7 million persons), the annual number of hospitalized cases of influenza-associated pneumonia ranged from 1,065-2,259 (0.5-1.0 per 1,000 persons) among children <5 years old and 779-2,252 cases (0.1-0.2 per 1,000 persons) for persons ≥5 years old, depending on year and base rate used. In both countries, the number of non-hospitalized influenza-associated cases was several-fold higher than the hospitalized cases.
  
  
  CONCLUSIONS
  Influenza virus was associated with a substantial amount of severe disease in Kenya and Guatemala. This method can be performed in most low and lower-middle income countries.
authors.affiliation: International Vaccine Access Center, Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America.
authors.forename: James A
authors.initials: JA
authors.lastname: Fuller
authors.forename: Aimee
authors.initials: A
authors.lastname: Summers
authors.forename: Mark A
authors.initials: MA
authors.lastname: Katz
authors.forename: Kim A
authors.initials: KA
authors.lastname: Lindblade
authors.forename: Henry
authors.initials: H
authors.lastname: Njuguna
authors.forename: Wences
authors.initials: W
authors.lastname: Arvelo
authors.forename: Sammy
authors.initials: S
authors.lastname: Khagayi
authors.forename: Gideon
authors.initials: G
authors.lastname: Emukule
authors.forename: Nivaldo
authors.initials: N
authors.lastname: Linares-Perez
authors.forename: John
authors.initials: J
authors.lastname: McCracken
authors.forename: D James
authors.initials: DJ
authors.lastname: Nokes
authors.forename: Mwanajuma
authors.initials: M
authors.lastname: Ngama
authors.forename: Sidi
authors.initials: S
authors.lastname: Kazungu
authors.forename: Joshua A
authors.initials: JA
authors.lastname: Mott
authors.forename: Sonja J
authors.initials: SJ
authors.lastname: Olsen
authors.forename: Marc-Alain
authors.initials: MA
authors.lastname: Widdowson
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Feikin
mesh_terms: D003710:Demography; D006166:Guatemala / Q000453:epidemiology; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D015994:Incidence; D007251:Influenza, Human / Q000150:complications / Q000453:epidemiology* / Q000517:prevention & control*; D007630:Kenya / Q000453:epidemiology; D018571:Sentinel Surveillance; D045169:Severe Acute Respiratory Syndrome / Q000453:epidemiology* / Q000209:etiology