In Focus: Avian Influenza A(H7N9)
On 31 March 2013 the Chinese Center for Disease Control and Prevention announced the identification of a novel influenza A avian influenza virus, A(H7N9), causing severe illness in humans.
No similar viruses have been seen before and they differ genetically from A(H7) and A(N9) viruses that have been detected in Europe and elsewhere around the world.
It is the first time that human infection with influenza A(H7N9) virus has been identified. It is also the first time that human infection with a low pathogenic avian influenza A virus has been associated with fatal outcome in humans.
In response, ECDC provides regular updates on avian influenza A(H7N9) virus and continues to monitor and assess the situation. This work is done in collaboration with WHO, US CDC, China CDC and other partners.
ECDC's latest updates and rapid risk assessments on avian influenza A(H7N9) virus are available in our news and epidemiological updates and risk assessments sections.
Other Avian Influenza viruses
Each novel influenza has to be evaluated for its potential to cause severe disease, a pandemic or both.
Some types of bird flu are more harmful for certain birds and animals. Since 1996, a particular strain of bird flu known as A(H5N1) has emerged. First identified in Southern China and Hong Kong, it may have been around for longer than that elsewhere in the Far East. The A(H5N1) viruses kill a high proportion of poultry that they infect. They also infect a surprisingly wide range of birds and animals and have persisted over time and spread to poultry in a number of countries with poor infection control in poultry flocks.
A(H5N1) occasionally infects humans in contact with infected poultry. Because it causes severe disease in humans, it has to be taken seriously by European public health and animal health authorities. Though occasionally present in European wild birds, A(H5N1) viruses have never become established in poultry in Europe because of high levels of biosafety. Also the viruses have not adapted to be able to infect humans easily or transmit from person to person with any efficiency.