Novel Reassortant Avian Influenza A(H5N6) Viruses in Humans, Guangdong, China, 2015

On December 28, 2015, avian influenza A(H5N6) was detected in a throat swab sample from a patient (female, 26 years of age) with severe pneumonia by Shenzhen Municipal Center for Disease Control and Prevention (CDC). On December 31, 2015, another H5N6–positive case was detected in throat swab and tracheal aspirate samples from a patient (female, 40 years of age) with fever by Zhaoqing Municipal CDC. Both viruses were further confirmed to be H5N6 by full genome sequencing conducted at Guangdong Provincial CDC. Both H5N6–infected patients died; their deaths were reported to National Health and Family Planning Commission (NHFPC) of the People's Republic of China and World Health Organization (WHO) Long–term avian influenza virus (AIV) surveillance was conducted in Guangdong province. We collected pairs of cloacal and oropharyngeal swab specimens from healthy poultry in several live poultry markets. Samples were stored in viral medium at 4°C until they were transported to the laboratory and then stored at –80°C until virus isolation. A 0.22–μm filter was used to sterilize the samples, which were then used to inoculate 9-day-old SPF embryonated eggs. After incubation at 37 °C for 72 h, allantoic fluid was harvested and tested by using the hemagglutination assay. Subtypes of the viruses were determined by conventional hemagglutination