Estimation of the national disease burden of influenza-associated severe acute respiratory illness in Kenya and Guatemala: a novel methodology

James A Fuller, Aimee Summers, Mark A Katz, Kim A Lindblade, Henry Njuguna, Wences Arvelo, Sammy Khagayi, Gideon Emukule, Nivaldo Linares-Perez, John McCracken, D James Nokes, Mwanajuma Ngama, Sidi Kazungu, Joshua A Mott, Sonja J Olsen, Marc-Alain Widdowson, Daniel R Feikin

Research output: Contribution to journalArticle

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.

METHODS AND FINDINGS: 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.

Original languageEnglish
JournalPLoS ONE
Volume8
Issue number2
Pages (from-to)e56882
ISSN1932-6203
DOIs
Publication statusPublished - 2013

Keywords

  • Demography
  • Guatemala/epidemiology
  • Hospitalization/statistics & numerical data
  • Humans
  • Incidence
  • Influenza, Human/complications
  • Kenya/epidemiology
  • Sentinel Surveillance
  • Severe Acute Respiratory Syndrome/epidemiology

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