In the month since federal authorities announced an outbreak of bird flu on dairy farms, they have repeatedly reassured the public that the wave of infections has no impact on the country’s food or milk supply and poses little risk to the public.
But the outbreak in cows could be more serious than initially thought. In an obscure online update this week, the Agriculture Department said there was now evidence that the virus was spreading among cows and from cows to poultry.
The New York Times has learned that officials in North Carolina have detected avian flu infections in a herd of cattle without symptoms – information that the USDA has not made public. The finding suggests that the infections may be more widespread than previously thought.
Whether there are asymptomatic animals elsewhere remains unclear because the USDA does not require farms to test cattle for infections. Farmers were reimbursed for the cost of testing, but only for 20 cows per farm that were visibly ill. This week the ministry announced it would begin compensating farms for testing cows without symptoms.
Federal officials have shared limited genetic information about the virus with scientists and officials in other countries. This is important to learn how the virus might evolve as it spreads.
They do not actively monitor infections in pigs, which are known to be effective hosts for the development of influenza viruses and are often kept near cattle. And officials said they had “no concerns” about the safety of milk, despite a lack of concrete data.
In joint statements in March, the USDA, the Food and Drug Administration and the Centers for Disease Control and Prevention reassured the public that pasteurized milk was safe. However, the FDA is still conducting tests to determine whether the procedure eliminates the virus. The authority did not want to say when the results of these tests would be available.
Some experts said authorities should not have claimed the milk was safe before they had the data, even if the likelihood of risk to people was low.
“I understand that the dairy market is very afraid of losing even a few percent of milk consumption,” said Dr. Michael Osterholm, an infectious disease expert at the University of Minnesota.
But, he added, “the idea that you can avoid this kind of discussion by just giving absolute numbers is not going to do them any good.”
The federal response so far reflects early missteps during the pandemic, he and other experts said. “It appears they have learned little from the communication lessons that Covid has taught us,” said Dr. Osterholm.
In an interview this week, Dr. Rosemary Sifford, the USDA’s chief veterinarian, said more than a dozen federal epidemiologists, about twice as many laboratory workers, field staff, and academic and government staff were involved in the investigation.
“Please remember that we have been dealing with this for less than a month,” she said. “We are working very hard to generate more information.”
USDA staff are only analyzing viral gene sequences from sick cows, but will release information to outside experts “in the very, very near future,” Dr. Sifford.
“We certainly recognize that we need to know more about the bigger picture,” she added.
If the department were more forthcoming, scientists outside the government could already be helping to contain the virus, Dr. Tom Inglesby, director of the Johns Hopkins Center for Health Security at the Bloomberg School of Public Health.
“The days when it was considered a good plan or acceptable for a government agency to manage all the data itself are long gone,” he said.
Part of the problem, some experts say, is that the USDA has long had the ability to both regulate and promote agriculture.
“We all want farms to thrive and we all want to have a stable food supply for the American consumer,” said Donn Teske, president of the Kansas Farmers Union. “But if you’re also responsible for supervision, that’s a small problem.”
The current version of the bird flu virus has been circulating in poultry, wild birds and, more recently, a variety of mammals since 2020.
As of Friday afternoon, the dairy cow outbreak had spread to 32 herds in eight states: Texas, New Mexico, Michigan, Kansas, Idaho, Ohio, North Carolina and South Dakota.
It is unclear how the outbreak began on dairy farms. Early data suggests there were at least two bird-to-cow transmissions of the virus in the Texas Panhandle and New Mexico, Dr. Sifford.
So far, the H5N1 virus in cattle appears to only affect lactating cows and only temporarily. There were no diagnoses in calves, pregnant heifers or beef cows and there were no deaths. But the virus appears to have spilled back from cows to poultry in at least one case in Texas.
This infected flock and poultry flock were on different farms. However, according to the Texas Animal Health Commission, the virus may have been transmitted between people or animals that came into contact with items contaminated with virus-laden milk.
Infected cows appear to carry large amounts of the virus in their milk. (However, the USDA has tested relatively few animals with nasal swabs and does not test feces, a common repository for viruses.)
Milking equipment on dairy farms is usually thoroughly cleaned at least once a day, but not sterilized. People who milk cows are encouraged to wear goggles, masks or face shields, but the recommendations are often ignored.
In cows infected with H5N1, milk production drops sharply and the milk becomes viscous and yellowish. “We have never seen anything like this before,” said Dr. Keith Poulsen, director of the Wisconsin Veterinary Diagnostic Laboratory.
(According to a spokeswoman for the North Carolina Department of Agriculture, milk from infected but asymptomatic cows appears to be unchanged.)
In interviews, some experts criticized the USDA’s testing recommendations, which until this week promised reimbursement only for a pool of obviously sick animals. Farmers may not have found many infections simply because they didn’t look for them.
To understand the extent and possible mechanisms of virus transmission, extensive testing of animals with and without symptoms is critical in the early stages of outbreaks, said Caitlin Rivers, an epidemiologist at the Johns Hopkins Center for Health Security.
Many experts noted that pigs are a key part of flu surveillance because they are susceptible to both avian and human flu. They could act as “mixing bowls,” allowing H5N1 to spread efficiently among people.
The USDA does not test pigs or require farmers to do so, Dr. Sifford.
Testing cows for H5N1 infection requires approval from a state official. Milk samples collected by an accredited veterinarian are typically packaged in tubes, packaged in insulated coolers, and shipped to a USDA-approved laboratory along with a unique identifier. Positive tests are then confirmed by the USDA national laboratory in Iowa.
Each step slows the rapid response needed to contain an outbreak, Dr. Inglesby. Testing should be simple, free and accessible, he said.
Dr. Sifford said the USDA has already received a “small number” of samples from cows with no symptoms. The ministry “urgently recommends testing before herds are transported between states, which includes asymptomatic herds,” the agency said in a statement.
Some state health departments and farmers are already frustrated with the federal approach. Several farms in Minnesota – none of the eight states with known cases – are sending cow blood samples to private labs to test for antibodies to the virus, which would indicate current or past infection, Dr. Joe Armstrong, a veterinarian at the University of Minnesota Extension.
Other dairy farmers are reluctant to test because they fear the bird flu scare could hurt their business, Dr. Amy Swinford, director of the Texas A&M Veterinary Medical Diagnostic Laboratory.
“I think there are a lot more dairies that have had this happen than the ones we got samples from,” she said.
Dairy farmers are struggling with low milk prices and high feed costs, said Rick Naerebout, executive director of the Idaho Dairymen’s Association.
“It’s already a very difficult economic situation, and when you think about the fact that you might lose 20 percent of your sales for a period of two to four weeks – that really makes the situation even more worrying,” he said.
Idaho banned imports of cows from the Texas Panhandle after news of an outbreak of bird flu there, but a week too late. Having an infected herd in Idaho despite those precautions “was kind of a gut shot,” Mr. Naerebout said.
Matt Herrick, a spokesman for the International Dairy Foods Association, said federal officials should provide more resources and equipment for farmers to protect themselves and release updates more widely, including through social media.
There is no mention of the bird flu outbreak on the USDA homepage. The last outbreak-related announcement from the Animal and Plant Health Inspection Service, a division of the department, was on April 2.
The USDA is researching vaccines to protect cattle against H5N1, but it is unclear how long it might take to develop them. Dr. Armstrong of the University of Minnesota Extension said many farmers and veterinarians are hoping the virus will “burn itself out.”
Instead, it can become a long-term problem. “The goal is to prepare ourselves,” he said. “Not because of this wishful thinking: ‘It will just go away.'”
Source link
2024-04-20 00:04:02
www.nytimes.com
