Bird flu is, famously, a illness that infects birds.
But on Monday, federal and state authorities reported {that a} person in Texas had examined optimistic for the illness, the second person within the US to contract avian influenza within the final two years. Stranger nonetheless, the affected person didn’t contract the illness from a sick rooster or wild chicken however from a cow, which was presumably contaminated with the virus. Rarely, if ever, have mammals contaminated people with chicken flu.
The Texas affected person reported just one delicate symptom — specifically, pink eye — and is recovering, based on the Centers for Disease Control and Prevention. Yet the information is the latest in a protracted string of recent headlines that increase issues concerning the threat that chicken flu poses to public well being. Avian influenza has ravaged home flocks, inflicting farmers to cull chickens by the thousands and thousands. It’s additionally decimated wild birds and plenty of marine mammals together with seals and sea lions. And the virus is spreading, reaching penguins in Antarctica and at the very least one polar bear in the Arctic.
These developments are regarding. But how apprehensive ought to we be? Here’s what to know concerning the threat to people and to the thousands and thousands of farmed and wild animals.
Bird flu fundamentals: What it’s, and the place it comes from
Avian influenza, or chicken flu, is a normal time period for the illness attributable to influenza viruses that primarily infect and unfold amongst poultry and a few wild birds. They’re distinct from viruses that trigger the flu in people, although they’re related.
These avian viruses are fairly frequent. They’ve been circulating for eons amongst wild waterfowl, comparable to geese and geese, with out inflicting them a lot hurt. Mild types of an infection are referred to as “low-pathogenic avian influenza,” or LPAI, which implies they’re sometimes not lethal to wildlife.
The sort of avian influenza spreading at the moment is completely different. Occasionally, an LPAI virus can bounce from wild birds to birds on poultry farms. As the virus replicates in densely packed warehouses of farmed birds, it may rapidly evolve and adapt in ways in which make it extremely lethal to poultry. At that time, it will get dubbed a “highly pathogenic avian influenza virus,” or HPAI virus. That’s what’s circulating at the moment — an HPAI virus.
Highly pathogenic chicken flu has induced outbreaks on poultry farms many occasions prior to now which have killed 1000’s to thousands and thousands of farm birds. What makes this explicit type of avian influenza virus so uncommon is that it simply spreads and causes extreme illness amongst wild birds and an rising variety of mammals. That’s uncommon.
The present pressure of avian influenza spreading at the moment descended from a virus that induced an outbreak on a goose farm in Guangdong, China, in 1996. The US first skilled one among these goose farm virus outbreaks in 2014 and 2015, which induced the demise and culling of tens of thousands and thousands of poultry birds and an unknown variety of wild birds. Then in 2021, a associated model of the virus arrived within the US — the reason for the present outbreak — that seems a lot better outfitted at infecting wild animals.
Bird flu turned massive information within the months that adopted when it began spreading by means of poultry farms. Farmers have been compelled to cull tens of thousands and thousands of turkeys and egg-laying hens, typically utilizing a ugly strategy. It cost the federal authorities and the poultry business lots of of thousands and thousands of {dollars} to handle and despatched egg costs hovering in late 2022 and early this 12 months.
Another person bought sick. Does that up my threat?
Poultry farms have been hit hardest in 2022, with a flare-up in late 2023. Yet during the last two years, the virus has continued to unfold — to completely different locations and to completely different sorts of animals. Including mammals.
Early in 2023, the virus killed thousands of sea lions. In March 2024, officers confirmed that goats in Minnesota and dairy cows in Texas, Kansas, and Michigan additionally examined optimistic for chicken flu. The USDA has also reported “presumptive positive test results” from dairy cow herds in New Mexico and Idaho. The company says milk, which have to be pasteurized earlier than getting into the business meals provide, stays secure to eat.
“Although we don’t yet completely understand the factors that led to infection of the dairy cows with HPAI, it is possible that unique viral properties combined with epidemiological and environmental conditions all played a role for the spillover of HPAI into cattle,” stated Diego Diel, an affiliate professor at Cornell University’s faculty of veterinary medication.
But what makes this regarding is the plain undeniable fact that people are mammals, too. As the virus makes the bounce from birds to mammals, what’s stopping it from leaping to people?
In the previous couple of years, a pair dozen folks worldwide — largely in components of Asia — have examined optimistic for this explicit form of chicken flu, all of which possible got here into shut contact with contaminated animals. Symptoms could also be nonexistent or delicate, comparable to eye redness or a light flu, or they could present up as a fever (above 100 levels Fahrenheit) and pneumonia and may show deadly. In the final 20 years, greater than 800 folks have been contaminated with chicken flu globally, and more than half of them died.
In the US, nonetheless, human infections — not to mention deaths — are uncommon. The first human case of avian influenza from the present outbreak was in 2022, when a Colorado farmer who was concerned in killing chickens examined optimistic. The man stated he was drained for just a few days however rapidly recovered.
The person in Texas, in the meantime, examined optimistic in early April, after he was uncovered to dairy cattle that have been “presumed to be infected” with extremely pathogenic chicken flu, per the CDC. The affected person is taking an antiviral medicine and recovering, the company stated. (Avian influenza poses a a lot greater threat to farmers, farm employees, and individuals who often work with wildlife than it does to the overall inhabitants.)
As for the remainder of us?
First, the excellent news: The chicken flu that contaminated the person in Texas (who’s a dairy employee, per Politico) is almost definitely incapable of spreading harmful infections to different folks across the planet, specialists say. Simply put, the virus doesn’t have the correct organic equipment to simply invade — not to mention flow into amongst — people. We have very completely different physiologies than birds and different animals that HPAI simply infects. (If you need to go deeper, take a look at our earlier explainer on this.)
TL;DR: The possibilities of you getting chicken flu anytime quickly are extraordinarily slim.
The unhealthy information is that influenza viruses evolve rapidly, and unpredictably. Not solely do they mutate, however they will additionally swap whole parts of their genomes with different viruses, creating new Franken-viruses, if two or extra of them infect the identical host. Under the fitting circumstances, this evolution might give the virus the instruments to copy extra simply in mammals, which might make future strains of chicken flu extra threatening to people.
Scientists at the moment are racing to determine what, precisely, these situations may be. More particularly, they’re in search of indicators that the virus is choosing up diversifications that make it extra more likely to replicate inside mammalian cells and — critically — to unfold from mammal to mammal, comparable to cow to cow or seal to seal.
“There are many unanswered questions about the current HPAI outbreak in cattle, but one of the key questions is whether the virus is being transmitted from cow to cow,” Diel stated.
One new study means that the virus has tailored to marine mammals and could possibly unfold amongst them. USDA officers, in the meantime, have stated that transmission of avian influenza amongst cattle “cannot be ruled out,” in a recent update concerning the dairy cow outbreaks.
“This virus is still relatively low risk for humans,” Marcela Uhart, a wildlife veterinarian with the University of California Davis School of Veterinary Medicine and senior writer of the brand new examine, said in a February assertion. But she additionally had phrases of warning: “As long as the virus continues to replicate in mammals, it may make it a higher concern for humans. That’s why it’s so important to conduct surveillance and provide early warning.”
How ought to we be serious about chicken flu?
Obviously it’s not nice that one other human examined optimistic for chicken flu. Again, he’ll possible be advantageous.
But this story is just not but over. Scientists are nonetheless making an attempt to determine how the virus is altering and what it signifies that cows are getting sick. The virus might evolve to develop into a threat, underscoring the significance of monitoring the outbreak carefully.
There’s one other robust actuality right here: Industrial animal agriculture, with 1000’s of animals packed collectively in warehouses, is a breeding floor for chicken flu. So even when this present outbreak amongst birds wanes, we’ll possible proceed to see new outbreaks within the a long time to come back, throughout completely different species. Eventually, that would pose a extra critical threat to people; the extra probabilities chicken flu will get to evolve, the extra alternatives it has to show into one thing harmful.
That raises advanced questions on our meals system, and the way we will make it more healthy for people — to not point out farmed animals and wildlife. To stop or gradual the unfold of zoonotic illnesses, like chicken flu and Covid-19, governments, meals firms, and farmers might want to make investments closely in surveillance (together with of untamed birds) and even vaccines, and so they could in the end have to make rather more critical adjustments to animal agriculture.
