An extensive, multi-agency public-health investigation into an avian influenza case involving a B.C. teenager has identified no additional cases nor evidence of human-to-human transmission.

The goals of the investigation were to identify any contacts who may have had exposure to the teenager, determine the source of exposure, and ensure that there was no risk of new infections from either the teenager or animal sources. The investigation also included testing of household pets, birds and other animals from nearby premises, and environmental (soil, water) testing.

To date, all tests on humans, animals and environmental samples related to this investigation have been negative for influenza H5. While it is reassuring that no further cases have been identified, officials have also not been able to definitively identify the source of the young person’s infection.

The investigation has determined the teenager was infected with the same strain of influenza H5N1 currently circulating in wild birds and poultry in B.C. (Clade 2.3.4.4b, Genotype D1.1).  Advanced testing at the BC Centre for Disease Control (BCCDC) Public Health Laboratory determined the whole genome sequence of the virus most closely matches that of wild birds found in the Fraser Valley area in October and was not directly related to outbreaks at poultry farms in B.C.

“Our thoughts continue to be with this young person as they remain in critical condition, and their family,” said Dr. Bonnie Henry, B.C.’s provincial health officer. “I am confident in the extensive public health investigation that was led by the Fraser Health team in partnership with the BCCDC Public Health Laboratory, our partners at BC Children’s Hospital and the chief veterinary officer. Though we have not been able to determine definitively the source of exposure, we were able to rule out many potential risks and ensure there are no further cases related to this young person.”

While this was the first case of H5N1 in a person in B.C. and the first acquired in Canada, there have been a small number of human cases in the U.S. this year, including one reported in a child in California last week.

Health, animal and environmental partners across B.C. have also been working together and with the Canadian Food Inspection Agency and other national and U.S. partners to respond to the increased detections of H5N1 avian influenza in poultry farms and wild birds in the province since early October.

Prevention measures
To protect yourself against avian influenza, the following prevention measures are recommended:

• Stay up to date on all immunizations, especially the seasonal flu vaccine.
• Do not touch sick or dead animals or their droppings and do not bring sick wild animals into your home.
• Keep your pets away from sick or dead animals and their feces.
• Report dead or sick birds or animals.
  • For poultry or livestock, contact the Canadian Food Inspection Agency (CFIA) Animal Health office: https://inspection.canada.ca/en/about-cfia/contact-cfia-office-telephone
  • For pets, contact your veterinarian or call the BC Animal Health Centre at 1 800 661-9903
  • For wild birds, contact the BC Wild Bird Mortality Line: 1 866 431-2473
  • For wild mammals, contact the BC Wildlife Health Program: 1 250 751-7246

If you have been exposed to sick or dead birds or animals or work on farm where avian influenza has been detected, watch for symptoms of influenza-like illness. If you get symptoms within 10 days after exposure to sick or dead animals, tell your health-care provider that you have been in contact with sick animals and are concerned about avian influenza. This will help them give you appropriate advice on testing and treatment. Stay home and away from others while you have symptoms.

About avian influenza
Avian influenza viruses occur naturally among wild aquatic birds and spread easily from bird to bird. Since 2022, there has been unprecedented global spread of avian influenza caused by the H5N1 virus. While it mostly affects birds, it can affect other animals too. In addition to cases reported in wild birds and poultry farms in North America, the virus has infected mammals including dairy cattle, foxes, skunks, marine mammals and more. There have also been isolated reports of H5N1 detections in goats and in a pig in the United States. There have also been reports of cases in humans, notably following exposure to infected animals.

In B.C., H5N1 has been detected in wild birds, on poultry farms and among small wild mammals, including skunks and foxes. Most cases have been reported during migration season when wild birds carrying the virus are in high numbers in B.C. Since the beginning of October 2024, at least 54 infected poultry premises have been identified in B.C., along with numerous wild birds testing positive.

In B.C. and Canada, there have been no cases reported in dairy cattle and no evidence of avian influenza in samples of milk.

Influenza viruses are adaptable and can change when strains from humans or different animal species mix and exchange genetic information. Avian influenza could become more serious if the virus develops the ability to transmit from person to person, with potential for human-to-human transmission.

Learn More:

Ministry of Agriculture and Food information on avian influenza: https://www2.gov.bc.ca/gov/content/industry/agriculture-seafood/animals-and-crops/animal-health/reportable-notifiable-diseases/avian-influenza-ai

BC Centre for Disease Control information on avian influenza: http://www.bccdc.ca/health-info/diseases-conditions/avian-influenza

Avian influenza: How can I protect myself? http://www.bccdc.ca/resource-gallery/Documents/Avian_flu_How_can_I_protect_myself.pdf

HealthLinkBC information on avian influenza: https://www.healthlinkbc.ca/illnesses-conditions/infectious-diseases/avian-influenza

Public Health Agency of Canada information on avian influenza: https://www.canada.ca/en/public-health/services/diseases/avian-influenza-h5n1.html

WorkSafeBC information on avian influenza: https://www.worksafebc.com/en/health-safety/injuries-diseases/infectious-diseases/types/avian-flu