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Emergency Planning and Preparedness

Avian Influenza A(H7N9) Virus

Last reviewed: October 11, 2017
Last updated: October 11, 2017

The World Health Organization (WHO) continues to receive reports of laboratory-confirmed cases of Asian lineage avian influenza A(H7N9) virus from Chinese authorities. Since early 2013, there have been 1562 case notifications through International Health Regulations with approximately 605 deaths.

The Ministry of Health and Long-Term Care (ministry) made the following updates on October 11, 2017:

  • The ministry revised its situational update on the Asian lineage avian influenza A(H7N9) virus.

Avian influenza A(H7) viruses normally circulate among birds. The avian influenza A(H7N9) virus is one subgroup among the larger group of H7 influenza viruses. Human infections with avian influenza viruses are rare but can occur, most commonly after a person is exposed to infected poultry or contaminated environments, such as live poultry markets.

There are a number of avian influenza A(H7N9) virus strains circulating globally. Since March 2013, an Asian lineage avian influenza A(H7N9) virus has been circulating in poultry in China. Other strains of avian influenza A(H7N9) have been responsible for outbreaks in domestic poultry flocks in Europe (Czech Republic, France and the Netherlands) since 2009. In the spring of 2017, a North American strain of avian influenza A (H7N9) first appeared in the United States and caused a number of avian influenza outbreaks in poultry operations in the Mississippi flyway, including Tennessee, Kentucky and Georgia. The European and North American strains of avian influenza A(H7N9) are genetically different from the Asian strain. As the Asian lineage virus has resulted in more human infections, the ministry is focused on providing screening, testing and treatment recommendations for patients with this virus.

Asian lineage avian influenza A(H7N9) virus

China first reported human infections with a new Asian lineage avian influenza A(H7N9) virus in March 2013. Since that time, China has reported annual waves of sporadic human infections with the avian influenza A(H7N9) virus. China is currently experiencing its fifth wave of avian influenza A(H7N9) activity, which started on October 1, 2016. The number of human cases reported during the fifth wave is higher than the number of cases identified during any of the previous four waves.

Humans infected with the Asian lineage avian influenza A(H7N9) virus can present with a variety of symptoms, ranging from no symptoms or mild illness (e.g., fever and cough) to more severe disease. Most reported patients have had severe respiratory illness (e.g., pneumonia).

Most human infections with the Asian lineage avian influenza A(H7N9) virus have occurred after exposure to infected poultry or contaminated environments. The upsurge in human cases during the fifth wave of activity in China may be due to increased human exposure to avian influenza A(H7N9) caused by a higher number of infected birds and increased contamination of the environment, mostly related to live poultry markets.

China has also reported some small clusters that have occurred among individuals that had close contact with individuals infected with avian influenza A(H7N9). Investigations of these clusters suggest there may have been limited person-to-person spread where there was unprotected close contact with cases. However, there is no evidence of sustained person-to-person spread of the Asian lineage avian influenza A(H7N9) virus. Some cases of Asian lineage avian influenza A(H7N9) infection have been reported outside of mainland China, but all of these infections have occurred in people who had travelled to mainland China before becoming ill.

The US Centers for Disease Control and Prevention have placed the Asian lineage avian influenza A(H7N9) at the top of the list of pandemic threats from among a dozen bird and animal influenza viruses. In the fifth wave of Asian lineage avian influenza A(H7N9) infections, researchers have noted changes in the virus's genetic sequence converting it from a low pathogenicity avian influenza (i.e., unlikely to kill poultry) to a high pathogenicity avian influenza (i.e., high mortality rates in poultry). This change from low to high pathogenicity may make it easier to identify infected birds and to implement control measures. Pathogenicity in poultry does not necessarily indicate the virus’s infectiousness, or disease severity, in humans.

Although there have been efforts by some jurisdictions to prepare to produce an influenza A(H7N9) vaccine, there is no vaccine available yet for the Asian lineage influenza A(H7N) virus. In February 2017, the World Health Organization reported that samples taken from several human cases demonstrated resistance to neuraminidase inhibitors (e.g., oseltamivir and zanamivir), a type of antiviral medication used for the treatment and prevention of influenza. However, the vast majority of samples testing positive for this virus remain susceptible to neuraminidase inhibitors.

The risk posed to the people of Ontario by this virus remains low based on an assessment of the information available at this time, namely:

  • the Asian lineage avian influenza A(H7N9) virus has not been reported in poultry outside of China
  • although recent genetic changes in the Asian lineage avian influenza A(H7N9) virus may result in the virus being more pathogenic to poultry, there is no evidence of increased transmissibility to humans or sustainable human-to-human transmission

Although the risk to Ontarians remains low, this virus is of public health significance. Since the most likely threat to Ontarians is from returning travellers infected while in China, health care workers should consider the possibility of avian influenza A(H7N9) virus infection in persons with respiratory illness who meet the exposure criteria as described in the case definitions.

The ministry has released guidance on the Asian lineage avian influenza A(H7N9) virus for health care workers and health sector employers. This guidance includes information about screening, laboratory testing, treatment recommendations, and appropriate occupational health & safety and infection prevention & control measures.

The ministry has also developed the Emerging Infectious Respiratory Disease Roadmap. This document outlines the health system's initial response actions to a confirmed human case of a novel infectious respiratory disease, such as the Asian lineage avian influenza A(H7N9) virus. Health care workers and health sector employers can use the Roadmap as a tool to prepare for their response role in the event that a confirmed case of Asian lineage avian influenza A(H7N9) is detected in their organization.

Ministry updates

Health System Emergency Management Branch Director’s Memo: Situational update on the avian influenza A(H7N9) virus and Middle East Respiratory Coronavirus – October 11, 2017

Further information about avian influenza A(H7N9)

For More Information

Ministry of Health and Long-Term Care
Health System Emergency Management Branch
1075 Bay Street, Suite 810
Toronto, Ontario
Canada M5S 2B1
Fax : 416-212-4466
TTY : 1-800-387-5559
E-mail : emergencymanagement.moh@ontario.ca

 

Health workers and health sector employers can call the Healthcare Provider Hotline for more information
Toll free : 1-866-212-2272

CritiCall Ontario provides a 24 hour call centre for hospitals to contact on-call specialists; arrange for appropriate hospital bed access and facilitate urgent triage for patients
1-800-668-4357