The Dose19:04What’s going on with H5N1 bird flu?
H5N1 is in the news again, and this time it has spread to cattle in several U.S. states. It has even infected a dairy worker in Texas. Global health epidemiologist Raywat Deonandan explains how avian flu is spreading, how transmissible it is, what vaccines are available, and why we shouldn’t be too worried just yet.
Beef cattle farmer Raquel Kolof of Gibsons, B.C., says she’s extremely concerned about recent outbreaks of a dangerous form of bird flu — also known as highly pathogenic avian influenza (HPAI) — in dairy farms across at least eight U.S. states.
Though she says protections are in place to prevent similar outbreaks from taking place north of the U.S. border, and there have been no confirmed cases of bird flu in Canadian cattle to date, she says she’s still worried “that it’s coming up here.”
“Cattle do move around … and 85 per cent of our beef market is handled in south Alberta, through massive, massive factories,” said Kolof, the owner and founder of Hough Heritage Farms. “They all conglomerate, they spread to each other and then it spreads from there.”
Despite that unease, experts say there’s no cause for alarm right now thanks to national food safety standards and steps being taken by the Canadian Food Inspection Agency (CFIA) to ensure that food producers adhere to necessary biosecurity measures.
HPAI is a strain of influenza that causes “severe disease and high mortality in infected poultry,” according to the U.S. Centres for Disease Control and Prevention (CDC).
HPAI typically spreads between birds and has a high mortality rate for avian species, according to Genevieve Toupin, the national veterinary program manager with the CFIA, whose team is responsible for the agency’s ruminant and swine programs.
She says the virus currently infecting U.S. cattle is the same that’s been circulated by migratory birds flying along the Pacific-Central Flyway for approximately the past two years.
Thirty-two herds across eight U.S. states so far have been affected by HPAI infections since government agencies made the announcement almost four weeks ago. It’s still not clear how the virus is spreading to and between dairy cattle.
While the virus’s name implies it only affects birds, other animals — including mammals — can catch H5N1.
“In fact, we’ve detected H5N1 in polar bears, sea lions, penguins, foxes, and the presumption there is they’re getting it from eating dead birds,” said University of Ottawa global health epidemiologist Raywat Deonandan, speaking with Dr. Brian Goldman, host of The Dose.
Symptoms among infected cattle include a sudden decrease in milk production, thicker milk, decreases in appetite and dry manure or constipation, according to the CFIA.
Humans are susceptible to HPAI, though cases are rare and there has been no confirmed human-to-human transmission.
Since 2003, nearly 900 people worldwide have been infected with H5N1, according to the World Health Organization. Canada has seen only one confirmed case, in 2013.
Infection occurs if the virus gets into a person’s eyes, nose or mouth, or is inhaled, according to the CDC. Symptoms in humans resemble influenza, including cough, shortness of breath, fever and body aches.
In serious cases, people can experience severe respiratory illness, including difficulty breathing and pneumonia, as well as neurological changes, and multi-organ failure.
An estimated 52 per cent of known human cases result in death.
“It’s not the typical seasonal flu that we’re all used to,” said Deonandan.
“However, it’s important to keep in mind that there are likely instances of people getting it and not even knowing it, because their symptoms were so poor, in which case the actual fatality rate will drop considerably.”
Some estimates suggest the true fatality rate for humans infected with bird flu is “probably around 14 per cent to 30 per cent,” he said.
In comparison, during the height of the SARS outbreak in 2003, the disease had a case fatality rate of roughly 11 per cent.
A Texas dairy worker in early April reportedly caught a case of bird flu from an infected mammal — likely a cow.
“The person in Texas … reported eye redness, or conjunctivitis, as their only symptom and is recovering,” according to the CDC.
For the first time ever, avian influenza, or H5N1 bird flu, was detected in roughly a dozen dairy cow herds across the U.S. About That producer Lauren Bird explores why scientists and public health officials are concerned about the cross-species transmission and whether humans are now at higher risk.
This was only the second-ever recorded case of a human infected with bird flu in the U.S. The first was a Colorado inmate who caught the virus while working on a poultry farm as part of a pre-release employment program.
So far, nearly all human cases have been from direct contact with infected poultry, according to the Public Health Agency of Canada, with no evidence of any sustained transmission between people.
Deonandan says he’s especially worried about bird flu mutating, infecting a pig, and subsequently infecting a human in a form that would let it spread.
“What we’re concerned about is [bird flu] will share DNA with a flu that is adapted to live in humans and learn how to live in humans, in which case it will move from person to person, with presumably the same alacrity with which the seasonal flu moves from human to human,” he said.
For her part, Kolof says she and other livestock producers already adhere to stringent safety standards to prevent the spread of infection and disease.
“One of the beauties of being a small-scale farmer is that I interact with my herd multiple times a day,” she said.
“I know and can see a change instantly.”
Toupin with the CFIA says working with stakeholders across the farming industry to coordinate the national response.
Cattle farms are being advised not to introduce any new animals into a herd, and to quarantine new animals for 21 days just in case the animal is incubating disease.
A team of scientists in Saskatchewan are part of the global push to create vaccines for avian flu. They’re trying to protect birds now and humans later if the virus mutates.
Farmers should also minimize contact between livestock and wild birds.
“We’re monitoring the situation closely,” she said. “I think that it’s not something that we should worry too much about [right now.]”
The Canadian Cattle Association declined an interview request to discuss this story.
Canadians can also continue consuming beef, milk and egg products, though experts agree that food should be properly cooked. Pasteurization, a specialized heating process, also kills any harmful pathogens if they were to show up in milk or milk products.
Deonandan says he’s drawing attention to bird flu to contextualize the threat it poses to humans.
“COVID-19 has shown us that there is a deep distrust of the so-called experts, deep distrust of authority,” he said. “By getting ahead of the narrative, by laying out the facts as we know them, maybe we can buy some more trust.”
