Demographic and ecological risk factors for human influenza A virus infections in rural Indonesia.

ABSTRACT

BACKGROUND: Indonesia has the world's highest reported mortality for human infections with highly pathogenic avian influenza (HPAI) A(H5N1) virus. Indonesia is an agriculturally driven country where human-animal mixing is common and provides a unique environment for zoonotic influenza A virus transmission. OBJECTIVES: To identify potential demographic and ecological risk factors for human infection with seasonal influenza A viruses in rural Indonesia, a population-based study was conducted in Cileunyi and Soreang subdistricts near Bandung in western Java from 2008 to 2011. METHODS: Passive influenza surveillance with RT-PCR confirmation of influenza A viral RNA in respiratory specimens was utilized for case ascertainment. A population census and mapping were utilized for population data collection. The presence of influenza A(H3N2) and A(H1N1)pdm09 virus infections in a household was modeled using Generalized Estimating Equations. RESULTS: Each additional child aged <5 years in a household increased the odds of H3N2 approximately 5 times (OR=4.59, 95%CI 3.30-6.24) and H1N1pdm09 by 3.5 times (OR=3.53, 95%CI 2.51-4.96). In addition, the presence of 16-30 birds in the house was associated with an increased odds of H3N2 (OR=5.08, 95%CI 2.00-12.92) and H1N1pdm09 (OR=12.51 95%CI 6.23-25.13). CONCLUSION: Our findings suggest an increase in influenza A virus infections in rural Indonesian households with young children and poultry.