＂50 Questions on Quality and Safety of Agricultural Products＂ What is ＂H7N9 Avian Influenza＂？

　　 H7N9 avian influenza is a new type of avian influenza, which was first discovered in Shanghai and Anhui at the end of March 2013. H7N9 avian influenza is a new subtype of influenza virus discovered for the first time in the world, which has not been included in China’s legal infectious disease monitoring and reporting system, and no vaccine has been launched until the beginning of April 2013. All patients infected by this virus have symptoms such as fever in the early stage. By April 2013, it has not been confirmed whether this virus has the characteristics of human-to-human transmission. In April, 2013, it was investigated that the gene of H7N9 avian influenza virus came from the gene rearrangement of wild birds in East Asia and chickens in Shanghai, China, Zhejiang and Jiangsu. The cases are distributed in Beijing, Shanghai, Jiangsu, Zhejiang, Anhui, Shandong, Henan, Taiwan Province, Fujian and other places.

　　H7N9 is a subtype of avian influenza. The outer membrane of influenza virus particles is covered by two types of surface glycoproteins, one is hemagglutinin (H) and the other is neuraminidase (N). H is divided into 15 subtypes and N is divided into 9 subtypes. All human influenza viruses can cause avian influenza, but not all avian influenza viruses can cause human influenza. Among avian influenza viruses, H3, H5, H7 and H9 can be transmitted to people, and H5 is highly pathogenic. H3 is a zoonotic disease. According to the characteristics of influenza virus, it can be divided into 135 subtypes of HxNx, and H7N9 subtype avian influenza virus is one of them. Previously, it was only found in birds, and no human infection was found. The biological characteristics, pathogenicity and transmission of the virus have not been analyzed and judged.　　　

　　Tips:

　　The incubation period of human infection with H7N9 avian influenza is generally less than 7 days. Patients usually show flu-like symptoms, such as fever, cough, less phlegm, which may be accompanied by headache, muscle aches and general malaise. Severe patients’ condition develops rapidly, showing severe pneumonia, with body temperature above 39℃ for the most part, and dyspnea, which may be accompanied by coughing up blood and phlegm; Acute respiratory distress syndrome, mediastinal emphysema, sepsis, shock, disturbance of consciousness, acute kidney injury and so on can rapidly progress.