Burden and seasonality of medically attended influenza like illness (ILI) in Ethiopia, 2012 to 2017

Abstract

Background: The influenza virus spreads rapidly around the world in seasonal epidemics, resulting in significant morbidity and mortality. Influenza-related incidence data are limited in many countries in Africa despite established sentinel surveillance. This study aimed to address the information gap by estimating the burden and seasonality of medically attended influenza like illness in Ethiopia. Method: Influenza sentinel surveillance data collected from 3 influenza like illness (ILI) and 5 Severe Acute Respiratory Illness (SARI) sites from 2012 to 2017 was used for analysis. Descriptive statistics were applied for simple analysis. The proportion of medically attended influenza positive cases and incidence rate of ILI was determined using total admitted patients and catchment area population. Seasonality was estimated based on weekly trend of ILI and predicted threshold was done by applying the "Moving Epidemic Method (MEM)". Result: A total of 5715 medically attended influenza suspected patients who fulfills ILI and SARI case definition (77% ILI and 23% SARI) was enrolled. Laboratory confirmed influenza virus (influenza positive case) among ILI and SARI suspected case was 25% (1130/4426) and 3% (36/1289). Of which, 65% were influenza type A. The predominantly circulating influenza subtype were seasonal influenza A(H3N2) (n = 455, 60%) and Influenza A(H1N1)pdm09 (n = 293, 38.81%). The estimated mean annual influenza positive case proportion and ILI incidence rate was 160.04 and 52.48 per 100,000 population. The Incidence rate of ILI was higher in the age group of 15-44 years of age ['Incidence rate (R) = 254.6 per 100,000 population', 95% CI; 173.65, 335.55] and 5-14 years of age [R = 49.5, CI 95%; 31.47, 130.43]. The seasonality of influenza has two peak seasons; in a period from October-December and from April-June. Conclusion: Significant morbidity of influenza like illness was observed with two peak seasons of the year and seasonal influenza A (H3N2) remains the predominantly circulating influenza subtype. Further study need to be considered to identify potential risks and improving the surveillance system to continue early detection and monitoring of circulating influenza virus in the country has paramount importance.

Sentinel surveillance for influenza A viruses in Lahore District Pakistan in flu season 2015–2016

“…Extended longitudinal studies are required to determine the reproducibility of this pattern and to identify interseasonal variations. Nevertheless, this temporal trend aligns with those presented in other studies from Pakistan [18,28] and from other countries in temperate regions like the USA and China [29][30][31][32], suggesting similar impacts of the various factors that drive influenza seasonality including climate, host, and virus characteristics [32,33]. In current study, influenza virus was not detected in samples from ILI & SARI patients, collected in week 46 and 47 (peak season for influenza), which might be attributed to small sample size (5-6 patients per day).…”

Respiratory syncytial virus in severe lower respiratory infections in previously healthy young Ethiopian infants

“…The epidemiology of viral respiratory infections is not well documented in Ethiopia, except influenza virus surveillance since 2008 [27,28], and to our knowledge, this is the first study evaluating the burden of RSV infection among young infants less than 6 months of age with ALRI in the country. Similar to previous studies [12,13], the clinical presentation was not different between RSV positive and negative infants except for higher rate of wheezing in those with RSV infection.…”

The Economic Burden of Influenza-Like Illness among Children, Chronic Disease Patients, and the Elderly in China: A National Cross-Sectional Survey

“…First, the economic burden was collected from ILI cases instead of confirmed influenza cases. As recommended by the WHO, ILI sentinel surveillance data can be used to estimate the disease burden of influenza for specific risk groups [ 47 , 48 , 49 ], which is less specific but sensitive and rapid than laboratory surveillance [ 50 ]. Therefore, ILI cases were used, given that nationwide laboratory surveillance was not available, and a population-based study could offer higher population representativeness.…”