Officials are working to understand how the virus spreads, the size of the outbreak, and quickly it could grow.
In early March, Texas veterinarian Dr. Barb Petersen began receiving calls from dairy owners with concerns over dying crows, pigeons, and other birds on their farms. Then, word came of barn cats suddenly dying, including half the cats on one farm.
Days later, the Amarillo vet started hearing about sick dairy cattle cows with unusual symptoms: high fevers, decreased appetite, and reduced milk production. Tests came back negative for typical illnesses.
Dr. Petersen, who monitors more than 40,000 cattle on a dozen farms in the Panhandle, drew samples from cattle and cats and sent them to a veterinary diagnostic laboratory at Iowa State University.
The samples came back for Type A H5N1, a bird flu virus never before found in cattle. It was the first time proof that the virus could infect cows had been produced.
As of May 1, the U.S. Department of Agriculture had confirmed infections in 36 herds.
“It was just a surprise,” Dr. Petersen recalled. “It was just a little bit of disbelief.”
Human Infections Confirmed
The veterinarian also noticed that there were sick people on nearly every farm with sick animals.“We were actively checking on humans,” Dr. Petersen said. “I had people who never missed work miss work.”
To date, two people in the United States have had confirmed H5N1 infections, with the most recent being a Texas dairy worker linked to the cattle outbreak, according to the U.S. Centers for Disease Control and Prevention (CDC).
Dr. Demetre Daskalakis, a CDC respiratory diseases official, told reporters Wednesday that two dozen people have been tested for the virus, and about 100 more have been monitored since the outbreak in cattle.
The official said the CDC had not noticed any unusual flu trends in areas with infected cows, but some experts wonder if anecdotal reports of sick workers could mean that more people caught the virus from the animals.
Dr. Petersen said some of the dairy workers’ symptoms included fever, body aches, stuffy nose or congestion, which is consistent with the flu. Some, like the worker diagnosed with bird flu, had conjunctivitis, a kind of inflammation of the eye.
Infectious disease epidemiologist Dr. Gregory Gray at the University of Texas Medical Branch in Galveston has been taking samples from livestock and people on two Texas farms, adding that mild infections among the workers have been reported on farms with cattle infections.
Dr. Gray said many workers are reluctant to be tested, making his research more challenging. It’s unclear if the workers have limited access to health care or fear revealing private health information. But without confirmation, no one knows if the workers had the bird flu virus or an unrelated illness.
“They seem to be linked in time and space, so one would say it’s biologically plausible,” said Dr. Gray.
Dr. Petersen said some of the sick workers seeking treatment were offered oseltamivir, an antiviral drug sold under the brand Tamiflu.
Additionally, according to CDC spokesman Jason McDonald, some farm workers who were exposed to infected animals or people were also offered the medication. State health officials are responsible for evaluating and providing treatment per federal guidelines.
Texas health officials provided the medication to the person known to be infected with H5N1 and their household members.
Two others who were exposed to infected animals at a second farm but tested negative were also given the medication, said Chris Van Deusen, a spokesman for the Texas Department of State Health Services. He was not sure if others had been offered medication.
‘A Scarlet Letter’
Dr. Kay Russo, a Colorado veterinarian who consulted with Dr. Petersen about the outbreak, said some farmers have been hesitant to allow health officials on their property.“This particular disease is looked at as a scarlet letter,” Dr. Russo said. “It has this stigma associated with it right now.”
She has called for wider testing of cattle, people, and milk.
“We do not know what we do not measure,” Dr. Russo said. “Unfortunately, the horse left the barn and took off a lot faster than we were able to mobilize.”
Recently, a federal order was issued requiring testing on all lactating dairy cows moving between states. Dr. Gray fears that could further hinder cooperation.
He said labs that conduct testing are required to report positive results to the USDA, but some farmers may avoid testing in hopes of outlasting the outbreak.
Reluctance to allow testing is “greatly hampering” understanding of how the virus spreads, how large the outbreak is now, and how quickly it could grow, Dr. Gray said.
“It’s a negative, very negative, effect,” he continued.
Dr. Petersen said she understands the farmers’ and workers’ hesitation. She also praised those willing to allow her to gather samples that confirmed the outbreak and reflected on what the results could mean.
“You immediately think about the cows, the people that care for them, and the families that have these farms,” she said. “You’re thinking about the big picture, long term. Your mind starts to go down that entire path of concern.”
