Avian influenza, or "bird flu," is a contagious infection caused by type A influenza viruses. It mainly affects birds but can infect humans and other mammals.
Avian influenza is a contagious infection caused by type A influenza viruses. It mostly affects birds but can infect humans and other mammals. Influenza viruses are classified into subtypes based on two surface proteins, such as H5N1 or H7N9. Avian influenza is caused by different subtypes than seasonal influenza in humans. Most people do not have immunity against these new avian viruses, meaning that many people could become ill if the virus changes in ways that allow it to spread easily from person to person.
Avian influenza viruses are sometimes referred to as low or high pathogenic avian influenza. These terms refer to the severity of illness in birds and not necessarily severity in humans. People should take
steps to protect themselves regardless of the severity of illness in birds.
Avian influenza viruses occur naturally in wild aquatic bird species and can spread to other wild and domestic bird and animal species.
- Since 2022, there has been global spread of highly pathogenic avian influenza A (H5N1 and related viruses) in many wild bird species and domestic poultry.
- There have also been infections in mammals, such as cats, dairy cattle, house mice, raccoons, minks, foxes, skunks, and marine mammals, and occasional infections in humans.
- From 2003 - January 2025, 964 human H5N1 cases, including 466 deaths, were
reported to the World Health Organization.
- In several US states, avian influenza A(H5N1) was detected in goats and dairy cattle for the first time in March 2024. Unpasteurized milk from sick cattle also tested positive for the virus. There have been occasional human cases of H5N1 in
persons exposed to infected dairy cattle in the US.
- To date, H5N1 has not been detected in cattle in Canada.
Influenza viruses can change when strains from humans or animals mix. Avian influenza could become a more serious concern if the virus develops the ability to spread from person to person.
- Overall, the current strain of avian influenza A(H5N1) circulating in birds in North America poses low risk to the public.
- People who come into contact with sick birds or other animals have a higher risk of infection and should take
precautions. This includes people who work or spend time near infected commercial and domestic poultry as well as other sick birds or mammals.
- On November 9, 2024,
a case of H5N1 was reported in a teen in Fraser Health region. Genetic analysis linked this infection to the H5N1 virus circulating in wild birds in BC and the public health investigation found no evidence of person-to-person transmission.
Avian influenza is monitored in birds, mammals, and people because of the potential for the virus to change and gain the ability to spread easily between people.
- Symptoms of avian influenza in humans may include fever, red eyes with discharge (conjunctivitis), cough, runny nose, sore throat, body aches, headache, nausea, diarrhea, or vomiting.
- Avian influenza can also cause serious illness and complications such as shortness of breath, chest pain, pneumonia, respiratory failure, and even death.
If you have had exposure to an infected bird or poultry premise and develop symptoms, contact your health care provider for testing. You should call first before visiting a health care provider to let them know about your exposure history and symptoms so they can take steps to protect others.
Human infections with avian influenza rarely spread to other people. There have only been a few cases where the virus spread to close contacts, such as people living in the same household as someone who was sick with avian influenza.
The following measures can help prevent infection:
- Avoid touching sick or dead birds and animals or their droppings and environments.
- Limit exposure to poultry farms or bird markets.
- Wash your hands regularly with soap and water, including after touching uncooked poultry.
- Do not eat raw or undercooked poultry products.
- Avoid eating/drinking unpasteurized milk or unpasteurized dairy products.
Wild aquatic birds, including gulls, terns, ducks, geese, and swans, are the natural reservoir (hosts) of virtually all influenza A subtypes. These viruses rarely cause illness or death in wild birds; however, with the current strain (H5N1) of avian influenza, wild birds are becoming sick and dying in greater numbers and more species are being affected. Avian influenza can spread to domestic poultry following direct contact with infected wild birds or indirectly through contaminated environments. Members of the public should avoid touching sick or dead birds and report dead birds to the British Columbia (BC) Wild Bird Mortality Line (1-866-431-2473). For sick/dead mammals, contact the
BC Wildlife Health Program at 250-751-7246. More information can be found here:
BC Wildlife Health Fact Sheet April 2022
Avian influenza detections in wild birds/animals in Canada are posted on the
CFIA's avian influenza wildlife dashboard.
Avian Influenza in BC Precautions for workers
There have been avian influenza transmission events observed in a wide range of wild mammalian species around the world such as house mice, raccoons, minks, foxes, skunks, and marine mammals. These may have been caused by direct contact with infected wild birds, scavenging on infected carcasses, or indirectly through contaminated environments. In BC, several detections of avian influenza have been reported in foxes, raccoons, and skunks. Wild mammals infected with avian influenza may show signs of neurological illness such as seizures, tremors, circling, excess salivation, or inability to walk. People who encounter a sick or dead wild animal should leave the animal where it is and contact a BC wildlife professional or contact the
BC Wildlife Health Program at 250-751-7246.
While the risk of transmission to humans is low, workers, and others who have contact with birds or wildlife, especially sick or dead animals should take precautions, such as wearing masks, gloves and protective clothing and washing their hands. Advice on safe handling of wild animals can be found here:
Wildlife exposure precautions for avian influenza.
Information for poultry owners and workers (October 2024)
Poultry flocks in Canada are usually free of avian influenza viruses. However, sometimes commercial or backyard birds become infected with avian influenza viruses through direct contact with infected wild birds or other infected poultry, or through contact with surfaces, feed, or water that have been contaminated with the viruses through infected bird feces or other secretions.
Avian influenza viruses can spread rapidly and cause outbreaks in poultry, which lead to devastating consequences for the poultry industry. Poultry owners can experience high mortality in flocks, food security can be threatened, and containment of outbreaks requires that all birds are culled on an infected farm. Avian influenza outbreaks have occurred in poultry in BC, including the extensive outbreak of H7N3 between February and May 2004, the H5N2 outbreak in December 2014, the H5N1 outbreak in February 2015, and the current H5N1 outbreak that began in April 2022. The current outbreak is connected to the global spread of H5N1 among wild and domestic birds and several mammalian species.
Status of ongoing avian influenza response by province - Canadian Food Inspection Agency (canada.ca)
Avian influenza outbreaks in poultry are of concern for several reasons:
- the potential for low pathogenic viruses to evolve into highly pathogenic viruses
- the potential for rapid spread and significant illness and death among poultry during outbreaks of highly pathogenic avian influenza
- the economic impact and trade restrictions
- the possibility that novel avian influenza A viruses with pandemic potential could be transmitted to humans
During an outbreak of avian influenza in poultry, the risk to the general public is low. Most avian influenza viruses cannot spread easily from birds to people, or from person-to-person. Public health officials work closely with animal health officials to ensure that poultry producers and workers who may have to come into close contact with infected birds are protected.
Poultry owners should take steps to
protect their birds, know how to recognize the signs of avian influenza, and where to report should their birds shows signs of avian influenza.
Other types of farmed animals may also develop illness due to avian influenza, including ruminants such as
dairy cows and goats, farmed mink, foxes and raccoon dogs. Mammal-to-mammal transmission is rare, but is occuring between cattle in the United States, and may have occured during an H5N1 outbreak in Spain between farmed minks.
For more information on
precautions for ruminants see the Canadian Food Inspection Agency’s page on ruminants and avian flu and the National Biosecurity Standards animal biosecurity page.
Avian influenza can also infect mammalian pets, such as cats and dogs, especially those who hunt, scavenge or eat infected birds. For example, cats that go outdoors may hunt and eat an infected bird, or dogs may scavenge dead birds. Pet owners should monitor their pets closely to ensure they don't come into contact with sick or dead birds and animals. To protect your pet, consider keeping cats indoors and dogs on a leash to avoid giving them access to potentially infected wild birds or their carcasses, especially during peak migration seasons. They should not be fed any raw meat or other products from game birds, poultry, or other animals infected with avian influenza. If pets develop signs of illness after exposure to sick or dead animals, owners should consult with their veterinarian. For more information on precautions for pets see the CFIA's guidance on pets and avian flu. Contact a veterinarian if you have concerns about your pet’s health.
It is safe to eat poultry products that are properly handled and fully cooked, as well as pasteurized milk products. Commercial poultry and dairy supplies have many safeguards in place to lower the risks of exposure to avian influenza viruses through food products.
In Canada, commercial birds from farms affected by avian influenza outbreaks are humanely culled and disposed of, and do not enter the marketplace. Poultry and poultry products (like eggs) should be
cooked thoroughly, which will kill bacteria and viruses, including bird flu viruses. Wash your hands regularly with soap and water, including after touching raw poultry and raw eggs.
In the U.S., unpasteurized milk from cattle infected with avian influenza tested positive for A(H5N1) in March 2024. In Canada, only milk from healthy dairy cattle or other livestock enters the commercial milk supply chain. Canadian Food Inspection Agency (CFIA) laboratories regularly test samples of raw milk from dairy farms across Canada, and to date all samples have tested negative for highly pathogenic avian influenza. Further, pasteurization of commercial milk products kills pathogens, including influenza viruses that may be present. Pasteurized milk and milk products, including pasteurized cheeses, are safe to consume. Consumers should avoid consumption of unpasteurized milk see the
Dairy Safety page for more information.
It is safe to eat poultry products that are properly handled and fully cooked, as well as pasteurized milk products. Commercial poultry and dairy supplies have many safeguards in place to lower the risks of exposure to avian influenza viruses through food products.
In Canada, commercial birds from farms affected by avian influenza outbreaks are humanely culled and disposed of, and do not enter the marketplace. Poultry and poultry products (like eggs) should be
cooked thoroughly, which will kill bacteria and viruses, including bird flu viruses. Wash your hands regularly with soap and water, including after touching raw poultry and raw eggs.
In the U.S., unpasteurized milk from cattle infected with avian influenza tested positive for A(H5N1) in March 2024. In Canada, only milk from healthy dairy cattle or other livestock enters the commercial milk supply chain. Canadian Food Inspection Agency (CFIA) laboratories regularly test samples of raw milk from dairy farms across Canada, and to date all samples have tested negative for highly pathogenic avian influenza. Further, pasteurization of commercial milk products kills pathogens, including influenza viruses that may be present. Pasteurized milk and milk products, including pasteurized cheeses, are safe to consume. Consumers should avoid consumption of unpasteurized milk see the
Dairy Safety page for more information.
