This article was originally published on KFF Health News.
In early February, dairy farmers in the Texas Panhandle began noticing sick cows. Word soon reached Darren Turley, executive director of the Texas Dairy Farmers Association. “It seemed like something was passing from herd to herd.”
It took about 60 days for veterinarians to identify the cause: H5N1, a highly pathogenic strain of the avian influenza virus. If it had been discovered sooner, the infection might have been contained quickly. The virus has now spread to at least eight other states and will be difficult to eradicate.
Currently, bird flu has not adapted to be airborne and spread from person to person like seasonal flu, which is necessary to spark a new pandemic. But this fortunate fact could change as the virus mutates in the infected cows. These mutations are random, but as the cow population grows, so does the chance of encountering a mutation that poses a significant risk to humans.
Why did it take so long to discover the virus on a high-tech farm in the world’s richest country? Because while the H5N1 virus has been circulating for nearly 30 years, its impact on dairy cows was unexpected. “People tend to think of an outbreak as starting at 9 a.m. on a Monday morning with a sign that says, ‘Here comes the outbreak,'” says Jeremy Farrar, a chief scientist at the World Health Organization. “That’s not the case.”
By investigating the source of the infection, researchers are gaining clues about how the infection started and spreads. That information can help limit the damage caused by the outbreak and, ideally, stop the next one. Local observations and genomic analysis have identified Texas as the epicenter of this cattle outbreak. To recount the events in Texas, KFF Health News spoke with more than a dozen people, including veterinarians, farmers and state officials.
An early indication that something was amiss on the Northwest Texas farm came from devices attached to the cows’ collars that Turley describes as “advanced fitness trackers” that collect an array of data, including the cows’ temperature, the quality of their milk, and how well digestion, or rumination, is progressing in their four-chambered stomachs.
When farmers downloaded the data in February, what they saw surprised them: One moment the cows seemed perfectly fine, and then four hours later they had stopped ruminating. “As soon as their stomachs stop moving, there’s a dramatic drop in milk volume,” Turley says. “That’s not normal.”
Tests came back negative for a contagious disease spreading through cattle herds that some farmers suspect may be linked to ash from wildfires that are devastating land in the east.
Looking back, Turley wishes he had painted more of the flocks of migratory birds that gather in the region each winter and spring. Geese and other waterfowl carried the H5N1 virus around the world, surviving large doses of the virus without getting sick, then transmitting it to local birds like blackbirds, cowbirds and crows that mix with the migratory flocks.
But among the many other problems facing dairy farmers, geese have flown under the radar. “One of the things you learn in agriculture is that Mother Nature is unpredictable and can be devastating,” Turley says. “Just when you think you have it figured out, Mother Nature tells you she doesn’t.”
Cat Clues
One dairy tried to isolate itself, being careful not to share equipment or employ the same staff as other farms, Turley recalled. But its cows still got sick. Turley noted that the farm was downwind from an outbreak on another farm, so “it almost makes you think there must be an airborne component to it.”
On March 7, Turley called the Texas Animal Health Commission. One Health Group Working with animal health, human health and agriculture experts, they looked into what they called a “mysterious syndrome.” State veterinarians examined the cows’ tissues for parasites, tested the animals’ blood and tested for viruses and bacteria, but found no cause for the illness.
They did not test for the H5N1 virus. Jumped into the mammals It has been transmitted dozens of times, but the infection rarely spreads between species. Most cases occur in carnivores, likely feeding on infected birds. Cattle are primarily herbivores.
“If someone told you their cows were producing less milk, you probably wouldn’t think to test for H5N1 because cows don’t get that virus,” said Thomas Peacock, a virologist at Britain’s Pirbright Institute, who studies avian influenza.
Post-mortem examination of crows, blackbirds and other birds The bird was found dead The detection of H5N1 in birds on the dairy farm didn’t change anything: “We weren’t too concerned because we were seeing birds all over the country testing positive for H5N1,” said Amy Swinford, director of the Texas A&M Veterinary Diagnostic Laboratory.
Meanwhile, rumors were circulating about a sudden increase in illness among dairy workers in the north, but it was flu season and hospitals were reporting nothing unusual.
Bethany Boggess Alkautter, research director at the National Farmworker Health Center, has worked in the Panhandle and speculates that farmworkers are less likely to be able to see a doctor when they need it. Clinics are far from where they live, she said, and many don’t speak English or Spanish. They might speak an indigenous language, such as Mixtec, common in parts of Mexico, for example. Medical costs are another obstacle, in addition to lost pay for time off work (or losing a job if they don’t go to work). “Even when medical care is there, it’s difficult,” she said.
Veterinarians eventually discovered the problem when several farm cats suddenly died and tested positive for the H5N1 virus. Swinford’s group worked with veterinary labs at Iowa State University and Cornell University to look for the virus in samples taken from sick cows.
“We got a call from Iowa State at 9 p.m. on Friday, March 22,” Swinford said. Researchers found antibodies to H5N1 in sections of mammary glands. By Monday, her team and others at Cornell had identified genetic fragments of the virus and notified authorities. In response, the U.S. Department of Agriculture announced that H5N1 had hit dairy cows.
Recalling rumors of farmworkers getting sick, Texas health officials urged farmers, veterinarians and local health departments to offer testing. About 20 people with coughs, sore, itchy eyes and other flu-like symptoms came forward to be swabbed and tested. Those samples were sent to the Centers for Disease Control and Prevention. All but one tested negative for H5N1. On April 1, the CDC announced its first case of the year: a farmworker with eye irritation that healed within a few days.
Thirteen dairies in the Panhandle were affected, said Brian Ball, field operations manager for the Texas Animal Health Commission. Dairymen reported that infections among their herds lasted 30 to 45 days, and that most cows had resumed normal milking schedules.
The observations suggest that herds do develop immunity, albeit temporarily. Indeed, early evidence indicates that H5N1 triggers a protective antibody response in cattle, said Marie Culhane, a professor of veterinary population medicine at the University of Minnesota. Still, she and other researchers remain worried because no one knows how the virus spreads or what risk it poses to people who work with cattle.
While most cows recover, farmers say the outbreak has upended their carefully timed schedule of milking, breeding and calving.
Farmers are hoping for answers that further research can provide, but the spirit of cooperation that existed in the first months of the Texas outbreak has disintegrated. Federal Regulation The measure has sparked backlash from farmers, who see it as an unfair punishment because pasteurized milk and cooked beef from dairy cows pose no risk to consumers.
Rules such as a 30-day ban on interstate movement of infected cattle pose problems for farmers who move pregnant cows to specialized calving farms, graze them in milder winter states, then return to their home states for milking. “When the federal mandate came, some producers said, ‘We’re going to stop testing,'” Ball said.
In May, the USDA Offered assistanceA range of grants will be available, including up to $10,000 to test and treat infected cows. “Financial incentives will help,” Turley said, but it’s not clear how much yet.
Federal officials are pressuring states to extract more information from farms and farm workers, a move veterinarians warn could strain relationships and stifle communication with farmers.
Faller, who has fought epidemics around the world, cited examples of how aggressive surveillance can drive infections underground, such as the bird flu epidemic in Vietnam in the early 2000s. The farmers avoided They break regulations by moving poultry at night, bribing inspectors, selling goods through back channels, etc. “It’s important to know what motivations and fears exist among people,” Farah said, “but we always seem to find out about it later.”
A powerful force in the United States: milk. A $60 billion industryPublic health will collide with politics in Texas, a state hit hard by pandemic restrictions and where lawmakers are Last year’s bill Prohibit health officials from recommending COVID-19 vaccines.
When Texas Agriculture Commissioner Sid Miller heard that federal investigators from the CDC and USDA were considering visiting farms, including those where farmers had reported that cows had recovered, he said he would not recommend the visits. “Are you going to send federal investigators to dairy farms that aren’t sick? I doubt it,” he said.
From Texas to the Nation
Peacock said Genomic analysis The H5N1 virus outbreak marks Texas as the epicenter of a cattle disease outbreak that occurred late last year.
“All these little jigsaw pieces confirm a circulation that hasn’t been detected in Texas for some time.” 1 report About the occurrence.
The evidence suggests that either a single cow was infected with the virus shed by a bird — perhaps a goose, crow or blackbird — or that the virus was transmitted from birds to cows multiple times, with a small percentage of it passing from cow to cow, he said.
The virus appears to have been carried to other states sometime in March when cattle were moved between farms. Limited genomic data is available. Linking the outbreak Texas produce is shipped directly to produce in New Mexico, Kansas, Ohio, North Carolina and South Dakota, but the data released by the USDA doesn’t include dates or locations, making the shipping routes inaccurate.
Researchers don’t want to be caught off guard again by the shape-shifting H5N1 virus, which means they need to keep watching humans. Of the roughly 900 people worldwide diagnosed with H5N1 infection since 2003, most, if not all, were infected by animals rather than humans, Farah says. About half of those have died.
He said it’s not enough to just occasionally test sick farmworkers. Ideally, a system would be created to encourage farmworkers, their communities and health care workers to get tested whenever the virus makes its way onto a nearby farm.
“Infections among health care workers are always a sign of human-to-human transmission,” Farah said. “That’s the approach that needs to be taken. I’m not saying it’s easy.”
KFF Health News is a national newsroom producing in-depth journalism on health issues and is one of the flagship operating programs of KFF, an independent source of health policy research, polling and journalism. KFF.
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