DENVER — Plans to modify livestock fairs and shows in Colorado this summer have not been drafted despite many unknowns about how bird flu is spreading among dairy cattle, state officials said Wednesday.
The comment from state veterinarian Dr. Maggie Baldwin, of the Colorado Department of Agriculture (CDA), came during a virtual town hall where state officials provided an overview of what they know about the growing outbreak of H5N1 in cows, and what the state is doing to respond to highly pathogenic avian influenza (HPAI, more commonly known as “bird flu”) among dairy herds.
So far, state officials have confirmed two outbreaks among dairy herds in northeast Colorado: The first on April 25, and the second on May 8.
As of Wednesday, nine states across the U.S. had confirmed outbreaks of H5N1 among 36 dairy herds, but those numbers are expected to continue going up as officials at both the state and federal level continue to catch up to the growing outbreak, which likely circulated undetected for months before it was officially confirmed in the U.S. on March 25.
While scientists have learned a few things about H5N1 in dairy cattle, like the fact that it appears to be primarily replicating in the mammary glands of cows, there are still many unknowns scientists are trying solve, Baldwin said.
Among the unknowns? How long it’s taking cows to show symptoms once they become infected, how exactly the virus is spreading among herds, how long it’s taking cows to rid the virus from their bodies, or what the risks are to exposed calves or other livestock species.
But despite these unknowns, Baldwin said guidance for stakeholders involved in county fairs and shows – events that are a couple of months away – have not yet been drafted.
“We don’t have guidance yet,” Baldwin said during a Q&A portion of the town hall, adding that “the USDA is looking to issue some guidance for shows and fairs, and we will follow their lead.”
It's not clear how much a federal order put in place on April 24 and adopted by the state not long after will be able to mitigate transmission among dairy herds, as the virus appears to be spreading among cows who aren't showing any symptoms and testing remains voluntary and encouraged only for visibly sick animals, according to STAT News.
Signs of HPAI in dairy cows include decreased feed intake, a significant drop in milk production and abnormal milk which appears thicker in consistency and discolored, Baldwin said. Other signs producers should watch out for in their herds are slight fevers and tacky stools, she added.
Though HPAI leads to severe disease and death in bird populations (hence the name “highly pathogenic avian influenza”), H5N1 isn’t proving to be severe or deadly in dairy cattle, Baldwin said.
“We are not seeing significant illness or mortality like in birds. Cattle appears to recover after supportive care,” she said.
How can I protect myself from catching bird flu?
Federal and state officials maintain that the risk to the general public for getting infected with bird flu is low, though risk depends on exposure, according to Dr. Rachel Herlihy, the state epidemiologist at the Colorado Department of Public Health and Environment (CDPHE).
“People who are exposed to sick birds and cattle are more likely to get infected,” she said during Wednesday’s town hall.
Only two cases of H5N1 among humans have been confirmed since the current outbreak started in the U.S two years ago: A Colorado poultry worker in April 2022 and a Texas dairy worker who was exposed to sick cattle in early March. In both cases, the workers experienced mild illness and recovered after a few days.
No human-to-human transmission of bird flu has been detected so far, and Herlihy said additional genetic changes in the virus would need to occur for that to happen.
She did warn, however, that “as the virus continues to spread among different species and spreads more widely, the virus has more opportunities to evolve and encounter humans more often.”
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Herlihy said the state is working on educating workers who are frequently exposed to sick poultry or cattle about how to protect themselves to reduce their risk of catching bird flu, such as wearing proper personal protective equipment (PPE), like N95 masks, goggles and gloves. She added dairy farm workers or people exposed to sick birds or animals should monitor for flu-like symptoms if feeling ill, get tested for influenza if seeking medical care and mention any recent exposure to sick birds or cattle. Those exposed to sick birds or cattle should also ask about getting antiviral treatment, she said.
During the town hall, Herlihy said the CDPHE had PPE available for any affected dairies or for any dairy what would like to provide it to their workers, and revealed that state health officials were monitoring 70 dairy farm workers who may have been exposed to H5N1, though no detailed information about those cases was immediately released.
“To date, none of them have reported symptoms of avian flu, so they have not met criteria to be tested for avian flu per Centers for Disease Control and Prevention,” a CDPHE spokesperson said in an email late Wednesday afternoon.
Testing would be available for anyone exposed to bird flu, and antivirals would be provided to those experiencing symptoms while awaiting test results, the CDPHE spokesperson added.
The general public should avoid contact with sick birds or other animals to reduce their chances of becoming infected with bird flu, Herlihy said. If you must handle sick or dead birds or animals, be sure to wear gloves, a high-quality mask such as a KN95 or N95 respirator, and eye protection. After handling the animal, double bag it and throw it away in your municipal trash can before thoroughly washing your hands.
How safe is the commercial food supply?
While early research lead by the FDA has detected remnants of bird flu in retail milk, follow-up studies in which scientists tried to grow live virus from those grocery store samples did not yield any positive results, which suggests that pasteurization is killing H5N1 in milk.
Other milk-related products that undergo pasteurization, such as cheeses, sour creams, yogurts, butters, etc., are also safe to eat, health officials said.
U.S. Food and Drug Administration (FDA) officials have said the likelihood that eggs will contain H5N1 is low “due to the safeguards in place, which include testing of flocks and federal inspection programs,” that call for the disposal of eggs and meat from infected poultry. Proper egg storage and preparation “further reduce the risk,” they said.
People should avoid raw milk and dairy products made from raw milk at the moment, scientists recently told STAT News, as raw milk does not go through the process of pasteurization, which kills harmful viruses and bacteria. In Texas, a large number of cats who were fed raw milk developed neurological symptoms and later died, though scientists said they could not completely rule out if eating dead birds caused the deadly infection.
Raw milk can't be sold in Colorado and a bill aimed at legalizing it for sale across the state died in the legislature this year, though Coloradans could still get it if they enter what's called a herd-share agreement.
While Colorado has "not yet tested for this particular virus in swine and beef cattle," according to Baldwin, ground beef appears to be safe for consumption after USDA officials found no virus in retail meat from states with bird flu outbreaks, though they said more testing will be done to determine if the virus can live in beef muscle tissue to "reaffirm consumer confidence" in the commercial food supply.
The state veterinarian also said the FDA was looking at expanding testing to other cattle species, though a timeline of when that would happen was not immediately known.
As the spread of H5N1 among dairy cows continues to evolve, Baldwin said the state is working to get answers as quickly as possible, “because the goal is to stop additional spread of this virus.”
Editor's note on May 9 at 3:45 p.m.: This story has been modified after state department of agriculture officials confirmed a second outbreak of bird flu among another dairy herd in northeast Colorado.
