Why the results surprised anyone is itself a surprise. After the state of California began testing dairy herds for highly pathogenic avian influenza, known also as bird flu or H5N1, in August, it found the pathogen on 645 dairy farms. More than half of those were discovered in the last month alone.
That many — roughly half of all dairy farms in the nation’s leading milk-producing state — confirm three facts.
First, testing is crucial. While California has been testing milk for H5N1 presence since the late summer, the U.S. Department of Agriculture only began its testing Dec. 5. Little surprise then that there’s little national data on the flu’s spread.
Second, where there are chickens and cows, there is bird flu, and where there are more chickens and cows, there is more bird flu.
While bird flu isn’t deadly to cattle, an estimated 124 million poultry have been either killed or culled due to the now almost three-year outbreak of H5N1. Still, bird flu has been found in dairy cows in 16 states and 61 humans in six states.
Third, bird flu is having widespread effects on milk production. Exactly how much, however, has yet to be quantified. Dairy scientists, who have little to no experience with avian flu in dairy cows, are struggling to determine its effects.
These unknowns add to the complex puzzle avian flu presents to dairy farmers and government officials. One week before Christmas, Gov. Gavin Newsom declared a state of emergency in California to “ensure government agencies have the resources and flexibility they need to respond quickly to this outbreak.”
Anecdotally, in-the-milking-parlor evidence suggests California officials and USDA may be on their flu watch for some time, according to Milkweed, a monthly dairy newspaper based in Wisconsin.
According to its Dec. 2024 issue, “cow activity collars,” explained as “Fitfits” for cows that measure “the cow’s temperature … and other biomeasures,” show that “even after six months post-infection, many previously infected cows’ rumination” — digestion — “has not bounced back to prior levels.”
That means “Herds have had milk losses from 6 pounds per day,” or about two-thirds of one gallon, “ to 20 pounds,” or nearly two and a half gallons per day. In California, however, the flu-based hit appears dramatic: “(S)ome infected cows have dropped 30 to 40 pounds per day …”
That’s a profit-draining 3.5 to more than 4.6 gallons per day of milk production per cow lost to avian flu.
Newsom’s California emergency order came on the heels of an announcement from the U.S. Centers for Disease Control and Prevention that confirmed “the nation’s first human case of severe [avian flu] illness in a patient in Louisiana,” reported the Los Angeles Times.
That case, per the New York Times, “is concerning to public health officials because of its severity” — which they would not detail. The Times did report, though, that “The patient was infected with a version of the virus that has been found in birds, not the one that is spreading in cows.”
This is a nightmare scenario for public health officials worldwide: an unchecked and lethal, non-human pathogen jumping from the animal kingdom to humans.
And, “(T)he more transmissions,” an infectious disease specialist told the Los Angeles Times in mid-December, “the higher the likelihood that some of these mutations will appear by chance and take off.”
Equally worrisome, today’s growing presence of bird flu appears to be reaching a critical stage just as the government machinery to address public health crises is being turned over from the finally engaged Biden Administration to a largely anti-oversight team of vaccine doubters and populist politicians with limited scientific expertise.
