A Clinical Analysis on Acute Lower Respiratory Tract Infections in Children Caused by Influenza Virus in Children

ABSTRACT

PURPOSE: Although annual epidemics occur, there are only a few clinical studies on influenza in Korea. We evaluated the epidemic and clinical features of acute lower respiratory tract infections in children by influenza virus. METHODS: From Feb., 1995 to July, 1997, influenza virus isolations and clinical review were performed on hospitalized children with acute lower respiratory tract infections at Hangang Sacred Heart Hospital. RESULTS: The influenza virus was isolated in 34 out of 545 (6.2%) patients examined. The number of influenza A and B viruses isolated were as follows 0 and 2 from Feb. to March, 1995, 8 and 1 from Nov., 1995 to May, 1996, and 15 and 9 from Dec., 1996 to June, 1997. The patients were 27 boys and 7 girls with a mean age of 27.6 +/- 25.1 months. Eight patients (23.5%) had preceding underlying diseases such as asthma, bronchopulmonary dysplasia and ventricular septal defect (VSD) with Down syndrome. Three out of twenty-two patients surveyed had been vaccinated against influenza virus before infection. The acute lower respiratory tract infections diagnosed were pneumonia in 11, bronchiolitis in 9, croup in 8, and tracheobronchitis in 6 patients. Fever, cough, and rhinorrhea developed in all patients and fever continued for a mean 5.5 +/- 4.0 days. All patients recovered without antiviral treatment except one expired case with penumonia/VSD/Down syndrome. CONCLUSION: Acute lower respiratory tract infections caused by influenza virus developed every winter and spring during the period of the study. Influenza vaccination before epidemic season should be encouraged in risky patients.