Demographic analysis of influenza-like illness categories including seasonal trend of swine flu cases attending a teaching hospital in Southern Rajasthan, India

Background: Influenza-like illness is a self-limiting non-specific acute respiratory illness characterized by common clinical features including fever, chills, malaise, headache, coughing, nausea, loss of appetite, and generalized weakness. Influenza A H1N1 is an important cause of ILI because it can lead to serious complications requiring hospitalization. Swine flu infection rates usually higher during the winter season in temperate regions. Objectives: This study is designed to analyze the demographic data of different ILI categories including seasonal trend of H1N1-related ILI in the patients attending a teaching hospital to know the spread and severity of diseases in Southern Rajasthan in India. Materials and Methods: It is a hospital-based retrospective study in which epidemiological and demographic data of all the patients attended swine flu outpatient departments, isolation wards, and intensive care unit were obtained and analyzed. All patients of ILI-B and ILI-C categories were tested for real-time polymerase chain reaction. Results: Of 3933 patients, 2686 (68.29%) patients were categorized in ILI-A, 724 (18.41%) patients were in ILI-B, and remaining 523 (13.30%) patients were in ILI-C. Overall, swine positivity among ILI-B and ILI-C categories was significantly (