SEASONAL TRENDS, DEMOGRAPHIC DISTRIBUTION, AND CLINICAL CHARACTERISTICS OF RT-PCR CONFIRMED INFLUENZA A (H1N1) CASES IN RAIPUR, CHHATTISGARH

Abstract

Background: Influenza A (H1N1) remains a significant public health concern, with seasonal outbreaks leading to considerable morbidity. Aim: To analyze the seasonal trends, demographic distribution, and clinical characteristics of RT-PCR confirmed Influenza A (H1N1) cases reported in Raipur, Chhattisgarh, in order to understand the epidemiological pattern, identify high-risk groups, and support effective public health planning and preventive measures. Methods: During the study period, 305 clinical samples were tested for Influenza A (H1N1) using RT-PCR, with a cycle threshold (CT) value ≤35 considered positive. Demographic, seasonal, and clinical symptom data were analyzed. Results: Of the 305 samples, 37 (12.13%) tested positive for H1N1. Gender distribution showed near-equal positivity between males (51.35%) and females (48.65%). The highest positivity rate was observed in the 11–20 years age group (23%), followed by the 41–60 years (13%) and 21–40 years (11%) groups. Seasonal analysis revealed a peak during the monsoon season (21 cases), followed by autumn (11 cases) and winter (4 cases), indicating a clear seasonal transmission pattern. Respiratory symptoms were predominant, with breathlessness and cough being the most common, while systemic symptoms such as fever, sore throat, nasal discharge, body ache, and abdominal pain were also frequently reported. Conclusion: H1N1 positivity showed no significant gender difference but varied across age groups and seasons, with monsoon being the peak period. Respiratory symptoms dominated the clinical profile. These findings highlight the importance of enhanced surveillance and targeted preventive measures during high-transmission seasons.