Canadian teenager infected with H5N1 bird flu is in critical condition

Canadian health officials announced Tuesday that a teenager infected with the H5N1 bird flu from an unknown source is in critical condition.

According to Bonnie Henry, British Columbia’s provincial health officerThe child is suffering from acute respiratory distress and was admitted to hospital on Friday.

The teen is the first suspected case of H5N1 bird flu in Canada.

“Our thoughts remain with this person and his family,” Henry said.

Authorities believe the virus was acquired through an animal source; However, the teen was not on a farm or near known wild birds or backyard poultry – common reservoirs for the disease.

Read more:How was H5N1 avian flu introduced into the California dairy industry?

According to a CBC interview with Henry, the teen did not have any contact with birds, but did have contact with a variety of other animals — including a dog, cats and reptiles — in the days before he became ill. Tests on these animals have so far been negative.

Health authorities are also tracing people the teenager came into contact with and have not identified any other infections so far.

The situation is “horrific,” said Jennifer Nuzzo, director of the Pandemic Center at Brown University. “The idea that we have a child, a teenager, who is seriously ill with this virus is actually an unmitigated tragedy. But unfortunately, that’s not surprising given everything we know about H5N1 and its potential to cause disease.”

She noted that since the late 1990s, when this current strain of bird flu originated in China’s Guangdong province, the fatality rate has been nearly 60%. That number is likely too high, she said, because presumably most people tested for the disease were those who went to hospitals or clinics to seek treatment; people who had mild symptoms or were asymptomatic were likely not tested.

Nevertheless, Nuzzo said that while this virus could be “a lot less deadly than what we’ve seen so far,” it could still be a lot deadlier than any pandemic we’ve seen in a long time, including COVID.

She said the case concerns her for three reasons: The first is the severity of the teen’s illness. The second is that “we don’t understand how the teen became infected,” she said. Her third concern is how government officials are handling this outbreak, which she described as “the spread of the disease from animals to people without trying to do more to prevent it.”

She said the virus may not ultimately become more virulent or efficient at moving between people, “but I don’t think we want to wait for the chance of that happening.”

Since the virus emerged in North American wild birds in 2021, human cases have been mostly mild. Since 2022, there have been 47 human cases in the U.S.: 25 in dairy workers, 21 in poultry workers and one case in Missouri, where the source has not yet been identified.

However, a recent study from the U.S. Centers for Disease Control and Prevention shows that the virus is more widespread among dairy workers than previously thought. An antibody study of 115 dairy workers from Michigan and Colorado showed that eight people were positive for the disease, or 7% of the study population – indicating that the workers were not reporting illness, or that they were asymptomatic.

Nuzzo also pointed to a recent study published in Nature, under the supervision of Yoshihiro Kawaokaan H5N1 expert at the University of Wisconsin, in Madison, who showed that the virus that infected the first reported dairy worker in Texas had acquired mutations that made it more severe in animals and also allowed them to move more efficiently between them – via the air breathing.

When Kawoaka exposed ferrets to this virus isolate, 100% died. Furthermore, the amount of virus they were initially exposed to did not seem to matter. Even very low doses caused deaths.

Kawoaka told The Times in an interview that the mutations seen in this particular isolate have appeared elsewhere in previous outbreaks in birds and mammals, “so in that sense it’s a very orthodox mutation.”

Read more:‘Worse than we hoped’: Bird flu deaths among California dairy cows are increasing

The isolate in the Canadian teenager has not yet been genetically sequenced – so it is unclear whether it carries these mutations or others.

Fortunately, that isolate has not been seen since it appeared in that one Texas dairy worker. It is unclear why the worker did not show more serious symptoms.

However, there are a few hypotheses.

Kawaoka’s research shows “inefficient replication” of the virus in human corneal cells. If the worker was exposed to a splash of contaminated milk in the eye, or by rubbing the eye with a contaminated glove, the virus may have stalled – unable to reproduce as it could have if the worker inhaled it had been exposed.

Nuzzo said there are other hypotheses — which she emphasized are just hypotheses — including one that posits that people exposed to the H1N1 swine flu in 2009 may have acquired some immunity to the “N1” part of the virus. virus.

The other goes back to a person’s first exposure to the flu.

There is a scientific hypothesis called the “original antigenic sin” that suggests that a person’s first exposure to a particular virus could “set the tone” for that person’s immune system in the future – so the first exposure to this worker’s flu may have provided his immune system with the defenses needed to suppress H5N1.

“There are many more questions than answers at the moment. So there are many interesting hypotheses about why the more recent cases have been mild. There is not enough evidence to simply throw away more than two decades of evidence about this virus. us that it could be quite deadly,” Nuzzo said.

As human flu season approaches, Nuzzo says it’s critical that people do what they can to prevent the spread of disease.

She said both seasonal flu and H5N1 vaccines should be provided to dairy workers.

Unfortunately, she said, “our surveillance efforts to detect outbreaks on farms, while they are improving, are still not even close to what we need to know about these outbreaks.”

In the meantime, vaccines and antiviral medications should be available.

“The news of a very serious case of bird flu in humans is a huge wake-up call that should immediately mobilize efforts to prevent another human pandemic,” said Andrew deCoriolis, executive director of Farm Forward. “We could have prevented the spread of bird flu on poultry farms across America, but we didn’t. We could have prevented the spread of bird flu on dairy farms, but we didn’t.”

“Factory farms notorious for raising billions of sick animals in filthy, cramped conditions provide a recipe for the emergence and spread of viruses like avian flu (H5N1),” deCoriolis said in a statement. “We are now on the brink of a new pandemic and the agencies responsible for regulating farms and protecting public health are moving more slowly than the virus is spreading.”

As of Wednesday, 492 dairy farms in 15 states have been infected with H5N1. More than half, 278, are in California. Two pigs in Oregon have also been infected.

This story originally appeared in Los Angeles Times.