Cause of H5N1 bird flu infection in B.C. teens still unknown, health officials say

Health officials in B.C. say they still don't know how a teenager became infected with the H5N1 strain of bird flu, but say no further cases have been identified.

Earlier this month, health officials announced they were investigating what is believed to be the first human case of H5N1 bird flu contracted in Canada.

The teen remains in critical condition, the province said Tuesday.

The Ministry of Health says the teen is from the Fraser Health region, which includes several eastern and southern suburbs of Vancouver and the Fraser Valley.

According to the ministry, bird flu – also called avian flu – is a virus that mainly affects birds, but can occasionally spread to humans through contact with infected animals or contaminated environments.

Although human infections with bird flu are rare, Health Canada says symptoms can range from mild to severe, potentially leading to pneumonia, organ failure and even death.

Provincial health officer Dr. Bonnie Henry said her thoughts are with the teen and their family.

“I am confident in the comprehensive public health investigation led by the Fraser Health team in collaboration with the [B.C. Centre for Disease Control’s] Public Health Laboratory, our partners at BC Children's Hospital and the chief veterinarian,” she said in a statement Tuesday.

In the time since BC announced the case, the U.S. Centers for Disease Control confirmed the first case of a child with H51N1 bird flu in California. In that case, the center said: the child had mild complaints and successfully recovers from the disease. An investigation is underway into the source of this exposure.

In total, 55 confirmed cases of H5 bird flu There have been reports in the United States in 2024, where the disease has been discovered in cattle, poultry flocks, wild birds and mammals and more, including isolated reports of infections in goats and one pig.

The BC Center for Disease Control says it has been working with the Canadian Food Inspection Agency and other Canadian and U.S. agencies to monitor the spread of the disease.

The investigation into the B.C. teen's case with H5 bird flu included testing of pets, birds and other animals from nearby buildings, as well as environmental testing of soil and water, the province said.

The investigation found that the strain the teen contracted was closely linked to the strain found in wild birds in the Fraser Valley area in October and was not directly linked to outbreaks on poultry farms in B.C.

No additional cases or evidence of human-to-human transmission have also been found.

Since early October, the H5N1 virus has been found in animals at numerous locations in B.C., including 22 poultry farms and in a variety of wild birds and small mammals such as foxes and skunks.

Millions of birds infected

In 2004, two workers at a poultry farm in the Fraser Valley became ill with the H7N3 strain of bird flu. According to Public Health Canada, H7N3 typically presents with mild symptoms, while H5N1 typically presents as severe.

Since 1997, more than 900 human cases have been reported worldwide, mostly in Asia and Africa, with about half of them resulting in death, according to Health Canada. However, the government warns that this death rate may be overestimated as mild infections often go undetected and underreported.

That's according to the Canadian Food Inspection Agency from November 2054 sites were actively dealing with avian flu infections in BC – the highest number among the provinces.

More than 6.8 million birds in B.C. are estimated to be affected.

In light of the confirmed cases among animals in British Columbia, officials are recommending residents avoid direct contact with sick or dead animals, keep pets away from affected wildlife and report dead or sick birds or mammals to the provincial authorities.