A detailed epidemiological and clinical description of 6 human cases of avian-origin influenza A (H7N9) virus infection in Shanghai

Abstract

Background: The world's first reported patient infected with avian influenza H7N9 was treated at the Fifth People's Hospital of Shanghai. Shortly thereafter, several other cases emerged in the local area. Here, we describe the detailed epidemiological and clinical data of 6 cases of avian influenza H7N9.

Methods and findings: We analyzed the epidemiologic and clinical data from clustered patients infected with H7N9 in the Minhang District of Shanghai during a 2-week period. Of the 6 patients, 2 were from a single family. In addition, 3 patients had a history of contact with poultry; however, all 6 patients lived in the proximity of 2 food markets where the H7N9 virus was detected in chickens and pigeons. The main symptoms were fever, cough, and hemoptysis. At onset, a decreased lymphocyte count and elevated creatine kinase, lactate dehydrogenase, procalcitonin, and C-reactive protein levels were observed. As the disease progressed, most patients developed dyspnea and hypoxemia. Imaging studies revealed lung consolidation and multiple ground-glass opacities in the early stage, rapidly extending bilaterally. All patients were treated with oseltamivir tablets beginning on days 3-8 after onset. The main complications were as follows: acute respiratory distress syndrome (ARDS; 83.3%), secondary bacterial infection (66.7%), pleural effusion (50%), left ventricular failure (33.3%), neuropsychiatric symptoms (33.3%), and rhabdomyolysis (16.7%). Of the 6 patients, 4 died of ARDS, with 2 patients recovering from the infection.

Conclusions: An outbreak of H7N9 infection occurred in the Minhang District of Shanghai that easily progressed to acute respiratory distress syndrome. Two cases showed family aggregation, which led us to identify the H7N9 virus and indicated that human transmission may be involved in the spread of this infection.

Figure 1. A map of patient residences and the 2 neighboring markets where H7N9 was detected in poultry.

Figure 2. Chest radiographic findings and progression of pneumonia in 6 patients with H7N9 infection.

Case 1: Panels A, B, and C; Case 4: Panels D, E, and F; Case 2: Panels G, H, and I. Early stage (panels A, D, and G): Chest computed tomography and radiograph show progressive consolidation in the lungs; Progressing stage (panels B, E, and H): Chest computed tomography and radiograph show bilateral ground-glass opacity and consolidation; Final stage (panels C, F, and I): Chest computed tomography and radiograph show diffuse lesions and bilateral involvement of the lungs (white lungs) in panels C and F, subcutaneous emphysema with pneumomediastinum in panel F, and diffuse lesions are obviously seen in panel I.