How a bird flu is plaguing the West

Richard Geary heard word of the contagion around the turn of spring, when it was still distant. News reports and murmurs among fellow veterinarians revealed livestock herds about 1,000 miles away in Kansas had fallen ill with a confusing new ailment. In the 35 years he’s been treating animals across southeast Idaho, Geary had never heard of anything like it. Nor did he think he’d soon be at the center of an outbreak that threatened national, even global, consequences.
Shortly after, highly pathogenic avian influenza — colloquially known as bird flu — was confirmed for the first time in dairy cows from New Mexico, Texas and Kansas.
“In my mind, I was thinking, ‘Well, I sure hope that they can contain it,’” Geary says. But just one week after the news broke, the first reported case reached an Idaho dairy farm and sent farmers into a panic. “Their questions to me and to the other veterinarian in my practice are: ‘What do you know about it?’” he says, “and, ‘What do we do when we get it?’”
Now, Western states like Idaho and Colorado have more infected livestock herds than anywhere else in the country.
Scientists discovered this strain of influenza, H5N1, in waterfowl almost three decades ago. It’s killed hundreds of millions of birds, either through complications posed by infection or mandatory cullings to prevent its spread. It’s infected bears, seals, sea lions, cats and dogs. Somewhere along its interspecies journey, as the scariest viruses do, it learned how to infect people, too. About 900 human cases have been recorded since 2003, and it’s estimated that more than 50 percent of those have been fatal. Yet the novel jump to cattle leaves scientists and farmers particularly worried. In the short term, there are economic lags and repercussions. An infected herd can cause tens or hundreds of thousands of dollars a day in production losses for farmers. But in the long term, there’s the potential for another pandemic.
Like the name suggests, highly pathogenic avian influenza is almost too easy to spread. Infected cattle circulate H5N1 through entire herds in a matter of days. Sometimes the infected cattle die of the disease. Sometimes they’re slaughtered in fear of spreading it. Although personal protective equipment like gloves, goggles and masks can prevent farmers from contracting the virus, all it takes is one virion — that microscopic single viral particle — in the eye, nose or mouth to infect a human. Ten dairy workers in the United States have already gotten the disease. There’s no publicly available vaccine to prevent it yet, either. And since influenza viruses are known to mutate and adapt to different species after enough exposure, these mounting cases among dairy farmers could lay down the groundwork for a more widespread human threat.
This outbreak is part of a new frontier for infectious diseases. From dengue fever to cholera, monkeypox to measles, and even other strains of influenza, illnesses are intensifying around the world. More than 900 new viruses have been discovered since 2009, and the Centers for Disease Control and Prevention reports 3 of every 4 emerging infectious diseases that affect humans originate in animals. Booming animal agriculture, growing human populations and changing climates create a perfect environment for viruses like bird flu to spread and adapt to new hosts. As those risks compound, pandemics grow more frequent. Experts predict the annual likelihood of extreme epidemics will increase threefold within the next few decades. How the West, the nation and the world responds to H5N1 will foreshadow how prepared the public is to live in a future with more of these viruses and their fallouts.
As much as half of all the biological material that makes up the human body is not actually our body. We are only about 40-50 percent human. Bacteria, fungi and viruses existing on and within every living person make up the rest. Viruses most of all. At any given time, a human being is host to around 380 trillion viruses. Many cause illness and infection. Some actually ward off disease. Most just tag along for the ride.
Viruses are genetic material, RNA or DNA, wrapped in protein. They vary in shape and size but are all exceptionally small — much smaller than bacteria and about 10,000 times smaller than a single grain of salt. They can infect plant, animal, bacterial and fungal cells by attaching themselves to receptors found along a cell’s surface before forcing their way inside. Once in a host cell, they replicate. Influenza viruses are among the most common viruses to result in infectious diseases. There are four types: A, B, C and D. Avian influenzas, including the current H5N1 strain in cattle, fall into the first category, a camp reserved for the viruses most capable of causing pandemics due to how rapidly they multiply.
When a virus jumps from one species to another, it’s usually by chance. Viruses train themselves over time to infect a particular host. But if another species has cells with similar receptor sites, and the virus comes into contact with those receptor sites, it can try to infect the unfamiliar species by swapping out parts of its genetic material with other viruses of the same type that already exist in that host. These reconfigurations are random. They’re difficult, maybe even impossible, to predict and usually don’t work. However, when they do, they can result in mass outbreaks. The swine flu pandemic of 2009 is the most recent example. A mishmash of influenzas that originated in birds, pigs and humans recombined to create a transmissible strain that killed more than 12,000 people in the United States alone.
For a pandemic to take place, a virus must be able to infect humans, spread easily from person to person, and be unfamiliar enough that the body has little or no immunity to it. So far, H5N1 checks two of the three boxes. The 10 confirmed cases in farm workers resulted in only minor symptoms. The most recent cluster of human infection took place on a dairy farm in Colorado in July — the first of its kind in the West. Each infected person so far has recovered and, although humans can contract it from cattle, the virus has not yet adapted to easily transmit from human to human. “There are lots of question marks in terms of how to prevent this from happening, and until we have proper epidemiology, we really can’t make strong recommendations to prevent it,” says John Swartzberg, a clinical professor emeritus of infectious diseases and vaccinology at UC Berkeley. “This virus could be spreading right now to lots of dairy workers and to their families, but we don’t know, because we’re not doing enough surveillance to find out.”
Nobody knows for certain how H5N1 jumped from wild birds to cows this past year. By the time health officials identified it, the virus had been spreading undetected for months. That gave it ample time to grow accustomed to this new host.
Now, since the virus can latch onto cell receptors in cows’ udders, dairy workers exposed to infected milk are left uniquely vulnerable. Worse yet, if H5N1 gets enough exposure to the human body through these dairy farm infections, it could similarly mutate to become more contagious among people. “What’s disturbing is that the receptor sites in the mammary glands of cattle are very similar to receptor sites in human beings,” Swartzberg says. “All of that increases the probability of spillover and then a pandemic.”
The risk to the general public is still low since pasteurization kills the virus in commercial dairy products. Though, to err on the side of caution, the federal government is contracting deals with pharmaceutical companies to develop H5N1 vaccines should the virus snowball into a public health emergency. Late-stage testing of these vaccines is only estimated to begin sometime next year. But to a virus — including this particular one — a year is like a hundred lifetimes. Plenty could change. Plenty already has.
When a bird flu outbreak overtook poultry farms across the country in 2022, the disease spread so quickly that it forced farmers to cull tens of millions of birds. It cost the poultry industry hundreds of millions of dollars and more than doubled the cost of eggs for consumers. News reports at the time speculated what would happen if the virus spread to other mammals on farms, and how it could heighten the risks for humans. The present outbreak in cattle is the next step in that evolution. It’s a manifestation of the fears that first surfaced just a couple of years ago.
At least nine counties across southern Idaho have had to quarantine dairy facilities due to H5N1 infection and exposure. “As quickly and as thoroughly as that spread through different herds of cows, I’m assuming that everybody either has got it or will get it,” Geary says. “My guess is it’s not a matter of if, it’s a matter of when that will happen.” Farms in different states have slaughtered some dairy cows that did not recover from the H5N1 virus, much like the cullings of infected poultry that took place during the last outbreak. But where a chicken can cost less than $500 a year to raise, each dairy cow costs farmers at least a few thousand dollars annually. Between production losses, thinned herds and sick farm workers, the financial strain has already proven brutal for those in agriculture. And it’s been less than a year since cows were even able to be infected with the virus.
Idaho is home to the third largest population of dairy cows in the country. There are more cattle than there are people, and — much to the potato’s chagrin — dairy is the single most valuable agricultural commodity produced in the state. “We have a much larger average herd size than the rest of the country,” says Rick Naerebout, chief executive officer of the Idaho Dairymen’s Association. “We’re milking about 2,500 cows on our average dairy. And so, looking at production losses, losing 20 percent of your milk production on a herd that size, that equates to just shy of $10,000 a day in losses.” Much of the Mountain West similarly relies on animal agriculture, which makes the region more susceptible to infectious diseases like this one.
The Department of Agriculture mandates dairy cattle be tested for avian influenza before herds can cross state lines, but it relies almost entirely on farmers to test and track cattle themselves. That not only places the burden on vulnerable farmers, it leaves room for error. There have been far more anecdotal reports of sick farm workers across the country in states with outbreaks than there have been confirmed human cases. This leaves health experts to speculate that many infections go untested and unreported. “You can imagine, if you were a rancher, the last thing you’d want to see is epidemiologists coming from the government to try and find evidence of infected cattle,” Swartzberg says. “And if they do find evidence of infected cattle, you don’t want to know that because it’s going to have a major impact on your business.”
In May, the federal government allocated $200 million to incentivize more surveillance, biosecurity and research on dairy farms. A program to compensate farmers for production losses launched in July. Now, dairy farmers can apply to receive funding that equals up to 90 percent of revenue lost due to H5N1 infections in their herds. “I think one of the things we’d really like to see (next) would be the option for our dairy producers to vaccinate for it,” Naerebout says. Especially since the virus looks as though it’s here to stay.
Whether this virus will evolve and threaten the next pandemic will depend not only on its ability to develop specific mutations, but on the attention paid to it. The World Health Organization views surveillance as a necessary pillar of an effective public health response. It is the first line of defense against the spread of viruses and the pandemics or epidemics that follow. As H5N1 continues to evolve and infect farmers on the front lines with Idaho at its epicenter, Geary tries his best to maintain that vigilance. At times it feels like it’s all he can do. “I feel for my producers that haven’t got it yet. Because it’s a hit that’s coming,” he says. “I would like to see them avoid that. But it’s probably not going to be that way.”
This story appears in the September 2024 issue of Deseret Magazine. Learn more about how to subscribe.