Epidemiology and Evolution of Influenza A/H7N9

Jih-Hui Lin1*, Shu-Chun Chiu1 ,Yu-Chen Hsu2

2015 Vol.31 NO.1

Correspondence Author: Jih-Hui Lin

  • 1.Center for Research, Diagnostics and Vaccine Development, Centers for Disease Control, Ministry of Health and Welfare, Taiwan
  • 2.Chief Secretary Office, Centers for Disease Control, Ministry of Health and Welfare, Taiwan


       The World Health Organization (WHO) has reported a first human infection by H7N9 virus from China in March 2013. Cases continued to be reported throughout April till now. There were four imported cases in Taiwan and one of them died. It has been established that many of the human cases of H7N9 appear to have a link to live bird markets except few cases. Due to the increasing travel frequency between Taiwan and Mainland China, it is needed to strengthen monitoring of the H7N9 virus and its epidemics. This study focuses on the epidemiology, genetics and evolution of H7N9 virus. The results showed that influenza tends to strike during the winter months, and the second wave which began in October 2013, although the mortality rate from  H7N9 infection is less than the first wave, however, the age and geographic distribution is broader. According to the genetic analysis data, the amino acids composition of this virus makes it easier to replicate and to infect human. To prevent the H7N9 epidemic in this winter period, any traveler visiting China and has influenza-like illness symptoms developed upon arriving in Taiwan, such as fever and cough, please put on a surgical mask and seek immediate medical attention. Moreover, physicians and medical workers should pay attention to patient’s recent travel history; include visiting live poultry markets, direct contacting with poultry and birds or their droppings/dead bodies, to facilitate the diagnosis and treatment.

Keywords:Influenza A/H7N9, epidemiology, genetic evolution