Analysis of 15 cases of avian influenza virus (H7N9) infection

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Objective: To describe the clinical, chest imaging, pathological manifestations and therapeutic experience of human infection with A/H7N9 virus. Methods: The features of 15 laboratory-confirmed cases of human infection with A/H7N9 virus in Taizhou, Jiangsu Province were retrospectively analyzed. Results: The 15 patients with confirmed viral pneumonia included 12 males and 3 females, with a median age of 61 years(ranging from 33 to 81 years). Twelve patients had a history of exposure to the poultry trading places, or direct contact with ill/dead avian, while 3 patients denied exposure or contact. The most common initial symptoms were fever, coughing, and respiratory distress. The illness progressed rapidly to acute respiratory distress syndrome (ARDS). Lab tests showed normal (8 cases) or decreased (7 cases)white blood cell count , decreased (13 cases) lymphocyte count and proportion , increased creatine kinase (CK, 12 cases) and lactate dehydrogenase (LDH, 15 cases), and respiratory failure (13 cases). Chest radiographic examination showed that the most common features were inflammatory infiltration in the lung, with partial consolidation. The average time of the diagnosis with influenza viral nucleic acid and onset of an oral anti-influenza drug were 7.1 days and 6.5 days. All patients were treated by antiviral drugs (oral oseltamivir 150 mg q12 h and/or intravenous paramivir 600 mg qd), with mechanical ventilation in 9 cases, glucocorticoid therapy in 5 cases (intravenous methylprednisolone in 3 and dexamethasone in 2 patients), extracorporeal membrane oxygenation (ECMO) therapy in 2 cases, continuous renal replacement therapy (CRRT) in 6 cases, and artificial liver therapy in 1 case. The pulmonary pathology was observed from post-mortem biopsy for 2 fatal cases. Patient 1 had diffuse alveolar damage with inflammatory exudation, hyaline membrane formation, and cellular infiltration. Patient 2 had widened alveolar septum, lymphocyte and monocyte cell infiltration in the alveolar septa, and interstitial fibrous proliferation. Nine patients were discharged, and 6 died. Conclusions: Patients with influenza A/H7N9 virus mostly presented with fever, cough, and were prone to progression to viral pneumonia. Once acute respiratory distress and important organ dysfunction occurred, the fatality rate was higher. Early diagnosis and rational treatment were critical for better outcomes.