Prevalence of Influenza Virus in Patients with Severe Acute Respiratory Infections (SARI)

BACKGROUND Influenza is viral fever with the main symptoms of the respiratory tract like cough, fever, breathlessness, nasal discharge, sore throat & myalgia. Pandemic 2009 H1N1 influenza A was the virus that presented a significant public health threat on a global scale. This prospective study was undertaken to analyse the prevalence of the influenza virus in patients with a severe acute respiratory infection (SARI) and also to determine the demographic characteristics and seasonal variations. METHODS This was a hospital-based prospective study done in the Department of Microbiology, Silchar Medical College & Hospital, Silchar for 1 year from June 2021 to May 2022. Respiratory specimens were tested for Influenza virus by one step real-time reverse transcription polymerase chain reaction (RT-PCR). RESULTS In real-time PCR, the influenza virus was detected in 6 out of 85 SARI patients (7%). Of 6 total positives, 4(67%) were influenza A and 2(33%) were influenza B. Among 4 influenza A positive cases, 3(75%) were influenza A (H1N1) pdm09 and 1(25%) was seasonal influenza A (H3N2). The highest percentage of positivity (50%) was detected in the age group of 15-29 years. The most common symptoms among the positive influenza cases were fever (100%), cough (88%), and breathlessness (56%). Other associated symptoms were sore throat (63%), nasal discharge (75%), and myalgia (75%). CONCLUSIONS This study clearly shows that influenza is an important cause of severe acute respiratory infection. It also suggests the need for continuous effective surveillance of influenza viruses to detect cases and control outbreaks. Early intervention and proper management of influenza virus cases are required to curb the disease burden.