Pneumonia due to 2009 Influenza A (H1N1) Infection in Thai children: Chulalongkorn experience

Abstract

Objective : To study the clinical presentations and outcomes of 2009 influenza A (H1N1) pneumonia children at King Chulalongkorn Memorial Hospital.

Setting : Department of Pediatrics, King Chulalongkorn Memorial Hospital.

Research design : Descriptive study.

Patients : Pediatric patients aged 1 month - 18 years who were admitted due to H1N1 influenza pneumonia between June 2009 – March 2010.

Methods : All the pediatric patients with pneumonia who had laboratory confirmation of 2009 influenza A (H1N1) infection by positive real-time reverse-transcriptase polymerase chain reaction (RT-PCR) assay for H1N1 influenza A virus in their nasopharyngeal aspirates or combined nasal and throat swabs were studied. Their demographic data, clinical presentations, laboratory results, radiological findings and clinical outcomes were analyzed.

Results : There were 37 patients with confirmed 2009 influenza A (H1N1) pneumonia during the study period. Male: female was 1.3: 1. The mean age was 6.4 ± 4.7 years (ranged 2 months - 16 years). Twenty-one patients (56.8%) had underlying diseases. Chronic lung disease and hematologic malignancy were the two most common underlying conditions. Only 43.2% of the patients (16/37 cases) had contact history and 7 cases got the infection while being in the hospital. The most common presenting symptoms were fever and cough (94.6%). Most of the patients had had fever with a mean temperature of 38.6 ± 0.9^ΟC (ranged 36.3 – 40.4^ΟC) for 50.0 ± 35.8 hours prior to hospitalization or diagnosis. The mean white blood cell count were 7,671 ± 62³ cells/mm.3 The most common chest X-ray finding was perihilar interstitial infiltration (62.2%) while patchy infiltration was noted in 13.5% of the patients. Ten cases (27%) had hypoxemia and 4 cases (10.8%) with underlying conditions developed into acute respiratory failure. Two patients (5.4%) died due to ARDS and severe sepsis.

Conclusion : Fever and cough with perihilar infiltrations were the most common clinical presentations of 2009 influenza A (H1N1) pneumonia in children admitted at King Chulalongkorn Memorial Hospital during the pandemic period. Respiratory failure occurred in patients with underlying diseases and accounted for 10.8% leading to a mortality rate of 5.4%. ARDS and superimposed bacterial infections were the major causes of death in this study.