Burden and epidemiology of influenza‐ and respiratory syncytial virus‐associated severe acute respiratory illness hospitalization in Madagascar, 2011‐2016

Abstract

Background Influenza and respiratory syncytial virus ( RSV ) infections are responsible for substantial global morbidity and mortality in young children and elderly individuals. Estimates of the burden of influenza‐ and RSV ‐associated hospitalization are limited in Africa. Methods We conducted hospital‐based surveillance for laboratory‐confirmed influenza‐ and RSV ‐associated severe acute respiratory illness ( SARI ) among patients of any age at one hospital and a retrospective review of SARI hospitalizations in five hospitals situated in Antananarivo during 2011‐2016. We estimated age‐specific rates (per 100 000 population) of influenza‐ and RSV ‐associated SARI hospitalizations for the Antananarivo region and then extrapolated these rates to the national level. Results Overall, the mean annual national number of influenza‐associated SARI hospitalizations for all age groups was 6609 (95% CI : 5381‐7835‐rate: 30.0; 95% CI : 24.4‐35.6), 4468 (95% CI : 3796‐5102‐rate: 127.6; 95% CI : 108.4‐145.7), 2141 (95% CI : 1585‐2734‐rate: 11.6; 95% CI : 8.6‐14.8), and 339 (95% CI : 224‐459‐rate: 50.0; 95% CI : 36.3‐74.4) among individuals aged <5, ≥5, and ≥65 years, respectively. For these same age groups, the mean annual number of RSV ‐associated SARI hospitalizations was 11 768 (95% CI : 10 553‐12 997‐rate: 53.4; 95% CI : 47.9‐59.0), 11 299 (95% CI : 10 350‐12 214‐rate: 322.7; 95% CI : 295.6‐348.8), 469 (95% CI : 203‐783‐rate: 2.5;95% CI : 1.1‐4.2), and 36 (95% CI : 0‐84‐rate: 5.8; 0.0‐13.5), respectively. Conclusion The burden of influenza‐ and RSV ‐associated SARI hospitalization was high among children aged <5 years. These first estimates for Madagascar will enable government to make informed evidence‐based decisions when allocating scarce resources and planning intervention strategies to limit the impact and spread of these viruses.

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

“…However, the rates of influenza‐associated ILI outpatient consultations were highest among individuals aged 5‐24 years, whereas the highest rates of influenza‐associated SARI hospitalization were observed among individuals aged <5 and ≥65 years, with children aged <5 years accounting for 63.1% of all influenza‐associated SARI hospitalizations. Higher rates of influenza‐associated SARI hospitalizations among young children and older adults have also been reported in other studies …”

“…In Step 1, we estimated the SARI hospitalization rate in Kinshasa Province (considered to be the base province in our estimation approach). In Step 2, we estimated the SARI hospitalization rates for the other provinces from the base province using a previously described methodology . In Step 3, we estimated the influenza‐associated SARI hospitalization rate using available virological surveillance data for influenza.…”

“…We estimated the provincial rates of influenza‐associated SARI hospitalization by multiplying the estimated provincial SARI hospitalization rates (obtained in Step 1 and 2) by the influenza virus detection rate obtained from influenza sentinel surveillance implemented among inpatients with SARI (data source 3) …”

“…We obtained the 95% confidence intervals (CI) using bootstrap resampling over 1000 replications for all parameters included in the calculations . This included (a) the age‐, year‐, and healthcare facility‐specific proportion of underreporting (data source 1 and 2), (b) the age‐, year‐, and healthcare facility‐specific proportion of ILI/SARI cases over total respiratory consultations/admissions (data source 3), (c) the provincial prevalence of the risk factors for pneumonia (data source 4), (d) the provincial proportion of ARI cases seeking care (data source 4), and (e) the age‐ and year‐specific influenza virus percentage positive among ILI/SARI cases tested (data source 3).…”

“…This included (a) the age‐, year‐, and healthcare facility‐specific proportion of underreporting (data source 1 and 2), (b) the age‐, year‐, and healthcare facility‐specific proportion of ILI/SARI cases over total respiratory consultations/admissions (data source 3), (c) the provincial prevalence of the risk factors for pneumonia (data source 4), (d) the provincial proportion of ARI cases seeking care (data source 4), and (e) the age‐ and year‐specific influenza virus percentage positive among ILI/SARI cases tested (data source 3). The lower and upper limits of the 95% CI were the 2.5th and 97.5th percentiles of the estimated values obtained from the 1000 resampled datasets, respectively . The statistical analysis was implemented using Stata 14.2 (StataCorp, College Station, Texas, USA).…”