Performance of WHO and CDC influenza-like illness (ILI) case definitions in detecting influenza in the tropics

Abstract

Background: Well structured and adequacy influenza surveillance system of Severe Acute Respiratory Infections (SARI) provide to determine a qualitative judgment on the severity of a current influenza epidemic or pandemic in comparison to past epidemics and pandemics. The aim of this study is to provide a research of sentinel surveillance of SARI in Serbia in 2018-2019 influenza season with matching between SARI hospitalizations and the percentage of influenza positive samples in order to testing the adequacy of SARI surveillance.Methods and materials: Sentinel SARI surveillance is performed from week 40 to 20 of the following year. Both epidemiological and virological data were collected on a weekly basis in 25 districts during the period of surveillance. For laboratory confirmation of influenza, Real time polymerase chain reaction (RT-PCR) was used. 10 sentinel hospitals in 4 cities participated in SARI surveillance system. Intensive care units (ICUs), infectious disease, pediatric and respiratory disease wards were all represented.Results: Start of influenza season was registered in week 52/2018. Influenza activity peaked between weeks 3/2019 and 9/2019, with the positivity rate higher than 50%. A total of 1117 SARI cases were reported with 100% recorded age. Of these, 13% were 0-4 years old, 6% were 5-14, 49% were 15-64 years old and 32% were 15-64 years old. Among these cases, 684 (61%) respiratory specimens were collected. The number of positive samples was 356 (52%).The highest proportion of laboratory-confirmed influenza cases was 69% in week 7/2019. Two influenza viruses were confirmed: A(H1)pdm09 and A(H3). A(H1)pdm09 viruses predominated, accounting for 90% of all sentinel SARI detections. The majority of cases with A (H1)pdm09 were registered <60 years of age.Among hospitalized influenza virus-infected patients with acute respiratory distress syndrome (ARDS) admitted to ICU wards (20% of all SARI reported cases), 100% were infected with type A viruses, and of those sub typed, 90% were A(H1)pdm09. Conclusion:Existing the high match between SARI hospitalizations and the percentage of influenza positive samples indicates the adequacy of sentinel SARI surveillance in Serbia. Integration epidemiological with laboratory surveillance highlights the importance of maintaining and improving national influenza surveillance capacity especially in the frame of International Health Regulations.

Trends in Influenza Infections in Three States of India from 2015–2021: Has There Been a Change during COVID-19 Pandemic?

“…SARI: An acute respiratory infection with measured fever of ≥38 • C and cough with onset within the last 10 days and requiring overnight hospitalization [13].…”

The weekly P25 of the age of the influenza-like illness shows a higher correlation with COVID-19 mortality than rapid tests and could predict the evolution of COVID-19 pandemics in sentinel surveillance, Piura, Perú, 2021

“…Syndromic sentinel surveillance, recommended by the WHO [ 10 , 11 ], is a strategy used by the CDC in the US and other places in the world for chronic and infectious diseases that links the clinic with the laboratory [ 12 – 14 ], which has been implemented at the Pachitea Health Center since 2013 in the city of Piura, in northern Peru, where influenza-like illness (ILI) is monitored. ILI syndromic surveillance based on clinical diagnosis of acute respiratory diseases includes confirmed and unconfirmed COVID-19 cases with laboratory tests.…”