The national and provincial burden of medically attended influenza-associated influenza-like illness and severe acute respiratory illness in the Democratic Republic of Congo, 2013-2015

Background Estimates of influenza-associated outpatient consultations and hospitalizations are severely limited in low- and middle-income countries, especially in Africa. Methods We conducted active prospective surveillance for influenza-like illness (ILI) and severe acute respiratory illness (SARI) at 5 healthcare facilities situated in Kinshasa Province during 2013-2015. We tested upper respiratory tract samples for influenza viruses using a reverse transcription-polymerase chain reaction assay. We estimated age-specific numbers and rates of influenza-associated ILI outpatient consultations and SARI hospitalizations for Kinshasa Province using a combination of administrative and influenza surveillance data. These estimates were extrapolated to each of the remaining 10 provinces accounting for provincial differences in prevalence of risk factors for pneumonia and healthcare-seeking behavior. Rates were reported per 100000 population. Results During 2013-2015, the mean annual national number of influenza-associated ILI outpatient consultations was 1003212 (95% Confidence Incidence [CI]: 719335-1338050 - Rate: 1205.3; 95% CI: 864.2-1607.5); 199839 (95% CI: 153563-254759 - Rate: 1464.0; 95% CI: 1125.0-1866.3) among children aged <5 years and 803374 (95% CI: 567772-1083291 - Rate: 1154.5; 95% CI: 813.1-1556.8) among individuals aged 5years. The mean annual national number of influenza-associated SARI hospitalizations was 40361 (95% CI: 24014-60514 - Rate: 48.5; 95% CI: 28.9-72.7); 25452 (95% CI: 19146-32944 - Rate: 186.5; 95% CI: 140.3-241.3) among children aged <5years and 14909 (95% CI: 4868-27570 - Rate: 21.4; 95% CI: 28.9-72.7) among individuals aged 5 years. Conclusions The burden of influenza-associated ILI outpatient consultations and SARI hospitalizations was substantial and was highest among hospitalized children aged <5 years.