Clinical features of three avian influenza H7N9 virus-infected patients in Shanghai

Since February 2013, a novel reassortant H7N9 virus associated with human deaths, but no apparent outbreaks in poultry and wild birds has emerged in eastern China.

The potential reemergence of H7N9 during next year's influenza season demand a further understanding of this important disease.

Between March 1 and April 30, 2013, we obtained and analyzed clinical, epidemiologic and radiologic features, and virologic data from three laboratory-confirmed patients of A H7N9 infection admitted in Shanghai Ruijin Hospital.

All patients were middle to old aged (mean age 62 years) and overweight (mean body mass index 31) patients. Two patients were exposed to poultry directly or indirectly in food market. They presented with fever and rapidly progressive pneumonia that did not respond to antibiotics. Time between onset of symptoms and onset of respiratory failure (days) were 7-11 days. Two patients presented secondary invasive bacterial infections. All patients died on day 7 to day 86 after the onset of symptoms.

Cross species poultry-to-person transmission of this new reassortant avian influenza H7N9 virus can result in severe and fatal respiratory disease like acute respiratory distress syndrome (ARDS) in humans. Reduplicate chest imaging examination is suggested for risky patients with fever and dyspnea. Secondary invasive bacterial infections and pneumothorax can cause severe and fatal consequence. Old age, obesity and presence of comorbidity may be associated with increased mortality. Pulmonary fibrosis can be seen at late stage of the disease.