Emergency Planning and Preparedness
Avian Influenza A(H7N9) Virus
Last reviewed: May 7, 2013
Last updated: May 7, 2013
On April 1, 2013, the World Health Organization (WHO) confirmed that there were instances of human disease caused by the avian influenza A(H7N9)virus in China.
Avian influenza A(H7) viruses normally circulate among birds, and the avian influenza A(H7N9) virus is one subgroup among the larger group of H7 viruses. Human infections with avian influenza viruses are rare but have occurred in the past, most commonly after a person is exposed to infected poultry.
This is the first time that this avian influenza A (H7N9) virus has been found in humans. This virus is different from other H7N9 viruses previously found in birds. Early genetic sequence analysis of the virus indicated it is a triple reassortant virus with genes derived from H7N9, H7N3 and H9N2 avian influenza viruses. A subsequent analysis has raised the possibility that the new virus arose from reassortment of four different avian influenza viruses, with two different H9N2 viruses contributing to internal genes.
Human cases infected with avian influenza A(H7N9) viruses present with a variety of symptoms that range from mild illness to more severe disease. Symptoms include conjunctivitis, fever and cough to fulminant pneumonia. Information is still limited about the full spectrum of disease that infection with the avian influenza A(H7N9) virus might cause.
There is no vaccine currently available for this influenza virus. Preliminary test results provided by the WHO Collaborating Centre in China suggest that the virus is susceptible to neuraminidase inhibitors (i.e.,oseltamivir and zanamivir).
On April 24, 2013 the WHO confirmed the first human case infected with the avian influenza A(H7N9) virus outside mainland China. This new case, in Taiwan, is being treated as an imported case as infection likely originated in mainland China where the individual worked.
The risk posed to the people of Ontario by this virus is considered low. This assessment has been made through consideration of the informationavailable at this time, namely :
- there is no evidence of sustained human-to-human transmission, and
- there is a limited geographic area with illness detection.
Although the current risk is low, this virus has public health significance and health care providers should consider the possibility of avian influenza A(H7N9) virus infection in persons with respiratory illness that meet the exposure criteria as described in the case definitions.
The Ministry of Health and Long-Term Care (ministry) has released guidance on avian influenza A(H7N9) virus for health workers and health sector employers with information about screening, laboratory testing ,treatment recommendations, and appropriate occupational health & safety and infection prevention & control measures.
There are a number of resources that health workers and health sector employers can turn to for more information on the avian influenza A(H7N9) virus :
- Ministry of Health and Long-Term Care's frequently asked questions page on avian influenza A(H7N9) virus
- World Health Organization's Disease Outbreak News Website
- Public Health Agency of Canada's Public Health Notice on the H7N9 avian flu in China
- United States Centers for Disease Control and Prevention's Website on Avian Influenza A(H7N9) Virus
- Morbidity and Mortality Weekly Report's Emergence of Avian Influenza A(H7N9) Virus Causing Severe Human Illness - China, February-April 2013