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.