A Five Year Profile of Clinical, Epidemiological and Radiological Characteristics of H1N1 Influenza in Children Admitted to Tertiary Care Center in South India

Introduction: Influenza viruses are common etiological agents of acute respiratory illness in children. Clinical presentation varies from flu like illness to severe respiratory and multi organ involvement. This study is done to describe the clinical profile and outcome of hospitalized children diagnosed with H1N1 influenza. Methods: A retrospective descriptive study was done at a tertiary care hospital in South India. It included children with swine flu diagnosed by RT-PCR assay of nasopharyngeal swab during the study period of five years. Data included clinical features, radiological findings, laboratory parameters, clinical course, complications and outcome. Results: There were 118 children with H1N1 Influenza. Median age was 4.35 years (IQR 0.8-10.7) with male:female ratio of 0.8:1. Fever was the commonest symptom present in 113 children (95.7%) followed by cough in 103 (87.2%) and nasal discharge (39.8%). Lower respiratory tract signs were present in 38 (27.9%) of the children. Co-morbid illness included malnutrition (33%), pre-existing wheeze (9.3%) and anaemia (6.8%). Anaemia was the common laboratory (36%) followed by thrombocytopenia (21.2%) and leucopenia (18.6%). Interstitial pattern was the commonest radiological finding (27.9%). Complications included secondary bacterial infection (27.1%), severe respiratory distress (16.2%), septic shock and MODS (5.9%), pleural effusion (3.4%), ARDS (2.5%), pneumothorax (1.7%) and PAH (1.7%). Mortality was observed in 5 (4.2%) children. Conclusion: The presence of co-morbid illness is a risk factor for severity of illness. Malnutrition and anaemia were risk factors for hospitalization and mortality.