Influenza and malaria coinfection among young children in Western Kenya, 2009-2011

Background.Although children <5 years old in sub-Saharan Africa are vulnerable to both malaria and influenza, little is known about coinfection.Methods.This retrospective, cross-sectional study in rural western Kenya examined outpatient visits and hospitalizations associated with febrile acute respiratory illness (ARI) during a 2-year period (July 2009-June 2011) in children <5 years old.Results.Across sites, 45 (149/331) of influenza-positive patients were coinfected with malaria, whereas only 6 (149/2408) of malaria-positive patients were coinfected with influenza. Depending on age, coinfection was present in 4-8 of outpatient visits and 1-3 of inpatient admissions for febrile ARI. Children with influenza were less likely than those without to have malaria (risk ratio [RR], 0.57-0.76 across sites and ages), and children with malaria were less likely than those without to have influenza (RR, 0.36-0.63). Among coinfected children aged 24-59 months, hospital length of stay was 2.7 and 2.8 days longer than influenza-only-infected children at the 2 sites, and 1.3 and 3.1 days longer than those with malaria only (all P <. 01).Conclusions.Coinfection with malaria and influenza was uncommon but associated with longer hospitalization than single infections among children 24-59 months of age.