On Monday, the U.S. Centers for Disease Control and Prevention announced that an unidentified individual in Texas had been diagnosed with the H5N1 avian flu following direct exposure to infected dairy cattle. This marks only the second confirmed case in the United States, with the first occurring in Colorado in 2022. Initial examination of the strain in the recent case indicates no noteworthy new mutations.
“This infection does not change the H5N1 bird flu human health risk assessment for the U.S. general public, which CDC considers to be low,” the agency said in a statement. According to the CDC, the person was diagnosed with infection after prolonged contact with dairy cattle “presumed to be infected with HPAI A [H5N1] viruses.”
The patient’s illness so far has been mild: The only symptom is conjunctivitis (redness) of the eye. “The patient was told to isolate and is being treated with an antiviral drug for flu,” the CDC said.
The CDC pointed out that while human cases of H5N1 are infrequent, they do sporadically arise globally. Given the surge of H5N1 avian flu among livestock in Texas this year, it might not come as a surprise that such a case occurred in the state.
In dairy cows, it “was first reported in Texas and Kansas by the U.S. Department of Agriculture [USDA] on March 25, 2024,” the CDC said. “Unpasteurized milk from sick cattle collected from two dairy farms in Kansas and one in Texas, as well as a throat swab from a cow in another dairy in Texas, tested positive” for the virus.
On March 29, infection was also found among a herd of dairy cows in Michigan that had received cows from Texas, the agency noted.
Importantly, the Texas Department of State Health Services noted in an alert that cattle infections “do not present a concern for the commercial milk supply. Dairies are required to destroy or divert milk from any sick cows, plus pasteurization kills avian flu viruses.”
However, since the initial reports of avian flu outbreaks among both wild and domestic birds in the United States in 2021, the CDC has consistently monitored its spread. While the emergence of a bird flu strain capable of human-to-human transmission is a significant concern, human cases have primarily occurred in individuals with close contact with infected animals.
Additionally, currently circulating strains of H5N1 seem to respond well to standard antiviral treatments.
“Preliminary analysis of A[H5N1] viruses has not found changes that would make these viruses resistant to current FDA-approved flu antiviral medications, so these are believed to be effective against these viruses,” the CDC said.
As for the human case in Texas, “CDC is working with state health departments to continue to monitor workers who may have been in contact with infected or potentially infected birds/animals and test those people who develop symptoms,” the agency said.
Should the virus ever mutate to spread easily among humans, the CDC says vaccines have been developed that should “provide reasonable protection against H5N1 influenza viruses.” The current seasonal flu vaccine would not help prevent infection with avian flu.
While the current threat to the public is low, the CDC said it continues to monitor H5N1 viruses nationally.
“This is a developing situation, and CDC will share additional updates as new relevant information becomes available,” the agency said.
In the meantime, the CDC says the odds of contracting avian flu can be diminished by reducing contact with live or dead animals, such as “wild birds, poultry, other domesticated birds, and other wild or domesticated animals [including cattle].”
Another big tip to avoiding H5N1: Stay away from unpasteurized milk products. That includes “raw” milk, cheeses and other such foods, the CDC said.
“FDA’s longstanding position is that unpasteurized, raw milk can harbor dangerous microorganisms that can pose serious health risks to consumers, and FDA is reminding consumers of the risks associated with raw milk consumption in light of the HPAI detections,” the agency said.
