Testing of throat-swab specimens from three patients who died of severe lower respiratory tract disease revealed infection with a novel reassortant H7N9 virus.
Because of the morbidity and mortality associated with H5N1 influenza, avian influenza virus infection in humans has garnered considerable attention. Now, investigators describe the clinical profile of three patients in China who died from complications of severe lower respiratory tract disease caused by a novel reassortant avian-origin influenza A (H7N9) virus.
Two of the patients (one residing in Shanghai, the other in Anhui Province) had been present at a chicken market within 7 days of illness onset; the third (also from Shanghai) had no known exposure to live birds within the preceding 2 weeks. All three patients had “high” fever, cough, and dyspnea, and all of them developed acute respiratory distress syndrome. All also had leukopenia, lymphocytopenia, and ground-glass opacities and consolidation on chest radiography, and two of them manifested rhabdomyolysis. Two patients died within 10 days of hospital admission, and the third one within 20 days.
Throat-swab specimens obtained from the patients were subjected to viral propagation in pathogen-free embryonated chicken eggs and RNA extraction. Real-time reverse-transcriptase polymerase chain reaction, genome sequencing, and phylogenetic analysis revealed that all three patients had been infected with a novel avian-origin influenza A (H7N9) virus.
Comment: On the basis of the findings from these patients, diagnostic tests for the novel reassortant H7N9 viruses have been developed. Public health officials around the world continue to closely monitor this outbreak, which serves as a reminder of influenza viruses’ unique capacity to evolve and cause respiratory tract infections in humans.
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