Ohio has become a significant hotspot for bird flu, with the state reporting its first probable human case on Wednesday and over 10.3 million birds infected in the past 30 days. This accounts for nearly 43% of the nation’s bird flu cases, according to data from the U.S. Department of Agriculture.
“We are closely monitoring the spread,” said Alex Woroncow, senior epidemiologist at Hamilton County Public Health. “Each new infection could bring the possibility of a new mutation.”
However, Woroncow reassured the public that there is no cause for panic.
“There is no evidence of human-to-human transmission,” he added. “The risk to the general public remains low.”
Bird flu, or H5N1, is a highly fatal strain of influenza A that primarily affects both commercial and wild bird populations. Unlike the common strains of influenza A that affect humans during flu season, H5N1 is mainly a concern for birds. Nonetheless, the disease can also spread to other animals, such as dairy cows, and household pets like dogs and cats, as per the Centers for Disease Control and Prevention (CDC).
Last year, a cat in Wood County, Ohio, located about 20 miles southwest of Toledo, was reported to have contracted bird flu, according to the USDA’s bird flu mammal infection tracker.
Although bird flu has been circulating among birds for over a century, the U.S. did not report its first human case until April 2022, raising concerns about the virus mutating into a form that could spread more easily between humans.
Human cases remain rare, with just 68 confirmed since 2024, compared to over 24 million birds infected in the past 30 days. Farm workers who have regular contact with poultry or dairy cows are at the highest risk of contracting the virus. However, for most people who do not work closely with animals, the risk is minimal.
Ohio’s first human case involved an adult male farm worker who had direct contact with commercial poultry. According to CDC data, 94% of confirmed infections in the U.S. have been linked to exposure through commercial agriculture.
Interestingly, not all humans with bird flu show symptoms. A CDC study released today revealed that 3 in 150 cow veterinarians had antibodies to H5N1 despite not exhibiting signs of illness.
The CDC previously published, then removed, a report suggesting that bird flu might spread between humans and cats. The report, which was posted by mistake on February 5, contained important information about the risks bird flu may pose to both people and pets. According to a copy of the report obtained by The New York Times, there were instances where an infected cat transmitted the virus to a human adolescent, and in another case, a farmworker infected with bird flu passed it to their cat. Both cats later died from the disease.
While human-to-cat-to-human transmission is rare, it is still a possibility. The first documented case in the U.S. occurred in 2016, when a veterinarian in New York City, who treated cats in shelters during a bird flu outbreak, experienced mild symptoms after coming into contact with the infected animals.
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