Canada has detected its first case of H5 bird flu in a person, a teenager in the western province of British Columbia, health officials said on Saturday.

This person is receiving treatment in a children’s hospital for H5 avian flu, the provincial health department said in a statement.

The source of contagion and any possible contacts are being investigated. Officials said the infection probably came from a bird or animal.

“This is a rare event,” British Columbia Health Officer Bonnie Henry said. “We are conducting a thorough investigation to fully understand the source of exposure here in B.C.”

H5 bird flu is widespread in wild birds worldwide and is causing outbreaks in poultry and United States dairy cows, with several recent human cases in US dairy and poultry workers.

It can occasionally infect humans through close contact or contaminated environments.

Scientists have voiced concern about the growing number of mammals becoming infected by bird flu, even if cases in humans remain rare.

They fear a high rate of transmission could facilitate a mutation of the virus, which could enable it to be passed from one human to another..

There has been no evidence of person-to-person spread so far. But if that were to happen, a pandemic could unfold, scientists have said.

Earlier in November, the US Centers for Disease Control and Prevention (CDC) asked for farm workers who have been exposed to animals with bird flu to be tested for the virus even if they do not have symptoms.

Bird flu has infected nearly 450 dairy farms in 15 US states since March, and the CDC has identified 46 human cases of bird flu since April.

In Canada, British Columbia has identified at least 22 infected poultry farms since October, and numerous wild birds tested positive, according to the province.

Canada has had no cases reported in dairy cattle and no evidence of bird flu in samples of milk.