Avian influenza (AI) viruses

Highly pathogenic avian influenza (HPAI) is caused by an influenza type A virus that can infect poultry (such as chickens, turkeys, pheasants, quail, domestic ducks, geese, and guinea fowl), and is carried by free-flying waterfowl such as ducks, geese, and shorebirds.

Avian influenza (AI) viruses are divided into subtypes based on the combination of 2 proteins: hemagglutinin or “H” proteins (H1–H16) and neuraminidase or “N” proteins (N1–N9). AI viruses are either high or low pathogenicity (HPAI and LPAI respectively), depending on the molecular characteristic of the virus and its ability to cause disease and mortality in domestic poultry.

Learn more about avian influenza in poultry.

Learn more about influenza viruses across domestic animal species.

Current situation

Domestic birds

There are currently no premises confirming the presence of HPAI in Ontario.

The last confirmed case of HPAI in domestic birds in the province was on January 30, 2024, in a commercial poultry flock in Essex County (Amherstburg).

The most recent HPAI detection reported in Canada was in Quebec on April 10, 2024, in a non-commercial flock. Updates on investigations and orders of avian influenza in domestic birds by province are provided by the Canadian Food Inspection Agency (CFIA) as available.

Although there are currently no active detections of HPAI in Ontario poultry, spring and fall are high-risk periods due to wild bird migration. It is recommended to keep all domestic poultry indoors during these periods when possible.

Other fall season activities such as fairs, shows, sales, competitions and swap meets, which involve the commingling of birds from different premises, are also considered high risk for HPAI and should be avoided.

It is generally recommended that bird owners not allow people who have recently been in contact with other birds (such as their own or attending a bird sale or show) to enter the housing area or handle birds.

Livestock

There have been no detections of HPAI in cattle or other livestock species in Ontario or Canada to date.

In early March 2024, newly kidded goats in Minnesota with exposure to an HPAI-infected backyard poultry flock tested positive for HPAI H5N1 after multiple goats died. Through genomic sequencing, it was determined the virus isolated from the goat kids and poultry on the farm were highly related. No additional goats were reported sick following March 11.

Separate to the goat detection, a multi-state outbreak of HPAI H5N1 in dairy cows has been ongoing in the United States since the first confirmed detection in milk samples from a dairy herd in Texas in late March 2024. To date, over 200 dairy herds in 14 states have been confirmed infected, with detections of the same virus strain affecting cattle also reported in farm workers, barn cats, poultry flocks and a herd of alpacas associated with the depopulation of infected poultry.

A small number of U.S. farm workers has also been identified as infected following exposure to infected cattle or poultry and displayed mild symptoms prior to recovery. The initial source of infection for cattle is believed to be a single transmission event from wild birds, with infection of additional cattle and herds through contaminated milking equipment, the movement of infected cattle and the movement of infected equipment, vehicles or shared workers between infected and non-infected premises. Read the U.S. Department of Agriculture’s national epidemiologic brief on H5N1 in dairy cattle (PDF).

Wild birds and mammals

Since November 3, 2021, the Canadian Wildlife Health Cooperative (CWHC) has reported a total of 2,951 positive HPAI detection with 517 positives in Ontario. In Canada, HPAI has been reported in 196 individual mammals from 12 different wild species.

Find more information on detections in Canadian wildlife.

Since December 30, 2021, the USDA has reported a total of 9,773 positive HPAI detection in wild birds. In the United States, HPAI has also been reported in 377 mammals across 23 species. These numbers include detection of HPAI in wild mammals but also in 36 domestic cats. Additional information on detections in American wild birds and mammals.

What to do if you find sick or dead birds/wildlife on your property

Report these findings to the Canadian Wildlife Health Cooperative at on-nu@cwhc-rcsf.ca or 1-866-673-4781 who may arrange for submission of wildlife for HPAI testing at the University of Guelph’s Animal Health Lab.

The recommendation to the public and pet owners continues to be to avoid direct contact with sick or dead wildlife, stray animals or wild birds.

If you must handle wildlife, follow the guidance on protecting yourself when handling sick, injured or orphaned wildlife.

Clinical signs

HPAI is a federally reportable disease in any species. Producers should report clinical signs or suspected illness in their flocks or herds to their veterinarian immediately. If veterinarians suspect HPAI in poultry or other species, they must report it to their local CFIA district office.

Clinical signs of HPAI in domestic poultry may include:

  • decrease in feed and water consumption
  • extreme depression
  • drop in egg production (many of which are soft-shelled or shell-less)
  • high and sudden morbidity and mortality rate
  • signs of septicemia (hemorrhages on the hocks, hemorrhagic enteritis, severe edema of eyelids, wattle and combs)

Clinical signs of HPAI in dairy cattle may include:

  • sudden reduced milk production
  • thickened or colostrum-like milk
  • decrease in feed consumption and/or drop in rumen motility
  • dry manure or constipation, rarely diarrhea
  • low grade fever

Veterinary guidance for testing of suspect cases or for non-symptomatic cattle for producer biosecurity decisions is available from the CFIA.

Food safety/zoonotic risk

Avian influenza is not a food safety risk, but consumption of undercooked meat or unpasteurized (raw) milk products from infected animals could pose a risk of virus transmission.

Also, avian influenza is not a significant public health concern for people who are not in direct contact with infected birds or animals.

To date, no sustained human-to-human transmission of HPAI has been reported anywhere in the world. Additional precautions should be taken and all public health guidelines followed for those who work directly with poultry and livestock, or in heavily contaminated environments.

While the annual human influenza vaccine does not protect against HPAI, it will help prevent you from getting seasonal influenza, which could weaken your immune system or resistance to other infections. There is no specific vaccine available for the H5N1 strain in people.

AI viruses can infect people via eyes, nose or mouth, or if the virus is inhaled through aerosol suspension. This is of concern for people who are in unprotected and routine contact with infected birds or contaminated surfaces.

Questions or concerns about human health and AI or HPAI should be directed to your local public health unit or your healthcare provider.

Signs of illness in humans

Based on studies of patients with the HPAI H5N1 virus, signs of illness in humans can range from very mild to severe. The most common signs include:

  • fever
  • cough
  • conjunctivitis (red eyes)
  • sore throat
  • runny or stuffy nose
  • muscle and/or body aches
  • headaches
  • fatigue or tiredness
  • shortness of breath or difficulty breathing

Less commonly, diarrhea, nausea, vomiting or seizures can occur. Diarrhea is more common with avian influenza than with influenza due to human viruses.

It is important to tell your healthcare provider or local public health unit if you have any of these signs and/or if you have been around sick or dead animals in the past 10 days which were suspected or confirmed to have had HPAI. Anti-viral therapy may be recommended and prescribed to you. If you are showing signs, specific tests to detect avian influenza in people are available.

If you do not have access to a healthcare provider, please contact Health811 by calling 811 or using the live chat feature.

Biosecurity

These poultry and livestock HPAI detections emphasize the continued importance of biosecurity measures across species.

Farm workers with risk of exposure to HPAI-infected animals are encouraged to take the appropriate precautions including using personal protective equipment. To date, testing in the U.S. has not identified changes to the virus that would make it more transmissible to humans, which would indicate that the risk to the public remains low.

In response to this outbreak, the CFIA has enhanced import controls and introduced additional measures for Canadian cattle returning from the U.S. to prevent the introduction of HPAI to Canadian dairy cattle. They have also conducted surveillance initiatives nationally on retail (pasteurized) and processor (raw) milk products.

American and Canadian pasteurization studies support that commercially sold milk and milk products remain safe to consume. The pasteurization process kills harmful bacteria and viruses, including HPAI, ensuring milk and milk products are safe to drink and eat. In Canada, milk must be pasteurized before sale. Raw (unpasteurized) milk products should not be fed to pets or livestock.

Additional information

Human health

United States

European Union