Which Avian Species in the U.S. have Contracted Avian Influenza?
Which Avian Species in the U.S. have Contracted Avian Influenza?
Over the last year, avian influenza, often referred to as bird flu, has spread significantly beyond the avian creatures of America. Primarily affecting farm animals, it has also infiltrated zoos, domestic pets, and even humans.
The danger to public health remains minimal. Nevertheless, experts are vigilantly monitoring the disease as it spreads and evolves among animals, keeping an eye out for any modifications that could improve its ability to infect humans.
What Is Bird Flu?
Commonly known as avian influenza, bird flu is a type of influenza virus classified under the H5 group. It has expanded extensively among wild birds worldwide in recent years, leading to outbreaks in poultry and cattle, bringing it closer to human contact.
In birds, the disease exhibits symptoms such as swelling in the head, watery eyes, and unusual movements. It can be lethal and is believed to have caused around 280 million deaths among birds since 2021. Approximately 127.47 million poultry have been affected by the disease across 50 states.
Cattle have also experienced severe manifestations of bird flu. Nearly 900 herds of cattle in 16 states have reported bird flu cases, according to the U.S. Department of Agriculture.
The virus is not well-suited to humans, usually resulting in mild symptoms in humans. As of now, only 66 human cases have been reported in the U.S. this year. The disease cannot spread from person to person, and most human cases have been linked to animal exposure.
Bird flu has been detected in raw milk samples, leading to product recalls due to public health concerns. Officials assure that pasteurized milk remains safe to drink as the process kills the virus.
What Other Animals Have Contracted Bird Flu?
Besides wild birds and poultry, numerous other animals have been affected by bird flu. A week ago, a Washington sanctuary reported the death of 20 big cats due to bird flu – more than half of its resident animals.
The sanctuary lost one Bengal tiger, four cougars, one African caracal, two Canada lynx, one Geoffroy cat, one Bengal cat, one Eurasian lynx, four bobcats, and five African servals. Previously, bird flu infections have been reported in other big and wild cat species, including Asian golden cats, Amur leopards, and clouded leopards.
"Cats are particularly susceptible to this virus, which can result in mild initial symptoms but progress rapidly, often leading to death within 24 hours due to pneumonia-like conditions," the Wild Felid Advocacy Center of Washington stated on its Facebook page.
Domestic cats can also contract the disease. An Oregon house cat recently died after consuming raw, frozen cat food contaminated with bird flu. Cases have also been reported in dogs, goats, and alpacas, according to the Centers for Disease Control and Prevention and the U.S. Department for Agriculture. Bird flu was also responsible for the death of a polar bear in Alaska.
Over time, various U.S. wild mammals, including mountain lions, bears, dolphins, seals, coyotes, foxes, martens, American minks, fishers, otters, raccoons, skunks, opossums, squirrels, mice, cottontails, and prairie voles, have all contracted bird flu.
The disease has spread globally, even reaching Antarctica, where it has resulted in significant deaths of penguins, elephant seals, and fur seals.
What Is the Risk of Bird Flu to Humans?
Specific proteins on the bird flu virus enable it to bind to sugars on the surface of the host animal's cells. The sugars on different animals have varying shapes, and some are better suited to the virus than others.
These bird flu proteins are well-adapted to birds and cows, whose sugars are relatively similar in shape. However, the human equivalent is shaped differently, making it more difficult for the virus to attach itself well. This results in generally milder symptoms and prevents bird flu from spreading between humans.
Experts are closely monitoring the virus as it spreads and mutates to see if it develops any adaptations that could make it better at binding to human cells.
Scientists at the Centers for Disease Control and Prevention recently announced the discovery of "low frequency mutations" in some of the proteins involved in binding in a sample from the nation's first severe human case.
Evidence suggests that the virus mutated within the Louisiana patient, who developed severe illness from their bird flu infection earlier this month. Although it remains "concerning," the CDC states that this change would be more alarming if it had happened prior to this specific infection. There is no evidence that the infection spread beyond this single patient.
Experts say the mutation does not yet allow for person-to-person transmission. “Is this an indication that we may be closer to seeing a readily transmitted virus between people? No,” said University of Minnesota infectious disease researcher Michael Osterholm. “Right now, this is a key that fits in the lock, but it doesn’t open the door.”
Mutations are a normal part of a virus's spread, which replicates itself imperfectly, resulting in minor changes. Most mutations will have little impact on how a virus transmits. Bird flu may never adapt in the way it needs to be able to pass between humans.
However, just in case it does, countries like the U.S. and the U.K. have already ordered millions of doses of an H5 bird flu vaccine.
Despite the minimal risk to human health, experts are keeping a close eye on avian influenza, monitoring its evolution among animals for potential modifications that could improve its ability to infect humans. The virus, classified under the H5 group, has spread beyond birds to affect animals like cows and even big cats in zoos, leading to the death of 20 big cats at a Washington sanctuary. Domestic cats, dogs, goats, alpacas, and even polar bears have contracted bird flu, highlighting its widespread impact on various animal species. While human cases have been mild and non-transmissible, scientists are closely watching for any mutations that could potentially allow the virus to infect humans more easily. To combat such a scenario, countries like the U.S. and U.K. have already ordered millions of doses of an H5 bird flu vaccine.