In 2011, an Oklahoma farmer had a herd of sick pigs. The animals look like the flu.
Virologist Benjamin Hause said: “Like a person with a respiratory illness, pigs have difficulty breathing, possibly a runny nose, cough and potentially a fever.
At the time, Hause was working at the company Newport Laboratories, which developed custom vaccines for cattle. Hause, now chief executive of Cambridge Technologies, another vaccine company, said: “We will detect and isolate pathogens from animals. Then we will grow pathogens in the lab. , destroy them and create a vaccine”.
The Oklahoma farmer took some samples from a pig’s nose – the same way you would pick your nose for a COVID test at home. He sent samples to Hause so he could figure out what caused the pigs to get sick.
Hidden virus: how the pandemic really started
NPR is running series of articles about the spreading virus — that’s when pathogens from animals jump into people. Researchers used to think spillovers were rare. Now it’s clear that they happen all the time. That has changed the way scientists look for new deadly viruses. To find out more, we went to Guatemala and Bangladesh, Borneo and South Africa.
Hause immediately thought that the common flu virus was infecting pigs. “We expected to find influenza A,” he said, “because that’s the most common problem.” It is also the same virus that commonly causes seasonal flu in humans.
But when he and his colleagues grew the virus in the lab, they quickly realized they were wrong. Hause was shocked by what he saw.
“I thought, ‘What is this? We’ve never seen anything like this before,'” he said. “We were immediately concerned that this virus could infect humans.”
Most infections are a mystery
For decades, scientists thought animal viruses rarely jumped into humans. They think these spillover effects are extremely rare. But over the past few years, studies have shown that this thinking is wrong.
“I do not think [spillover] is extremely rare,” said the evolutionary virologist Stephen Goldstein at the University of Utah. “I mean, we know this because when people start looking, people will find it.”
In fact, there’s likely to be a whole group of animal viruses that infect people all over the world without doctors knowing anything about them. They were hidden. They masquerade as the common cold, flu or even pneumonia.
For example, if you have a respiratory infection in the US, doctors can only identify the pathogen causing the infection about 40% of the time. There is increasing evidence that the other 60% of infections can be caused by animal viruses such as viruses coronavirus dog found in Malaysia, Haiti and Arkansas, or possibly even the same virus Hause and his colleagues establish in those pigs. Recent studies have made it clear that this virus is airborne on farms and has the potential to infect people who work there.
It’s everywhere they look
Hause and his colleagues eventually discovered that they had stumbled upon an entirely new influenza virus, unrelated to those known to infect humans. “It’s completely different from influenza A,” says virologist wind flower at the University of Kentucky, who co-led the discovery of the new virus.
When scientists started looking for signs of infection in other animals, besides pigs, they find it almost everywhere they look: in sheep, goats, camels, horses.
But Li says they hit the jackpot by looking at one particular animal: a cow.
“The percentage of cows in the US that have antibodies to influenza D is very high,” he said. “Whenever you Look In the herd, about 50% of cows have high antibodies to this virus. That’s really surprising.”
And it’s not just cows in Oklahoma but across the country, west to east and north to south, Li said. “From California to Vermont, and North Dakota to Texas, cows are infected with this virus. They are the main reservoir of the virus.”
In addition, the virus is extremely stable, Li said. “It can survive at high temperatures and in acidic environments,” he said. “That’s why scientists have establish influenza D in the air at airports in the US” They also establish it’s in the air at chicken farms in Malaysia.
And so the question is: If this virus can infect so many different animals and is found in so many cows, will it cause disease in humans? Especially those who work closely with cows on dairy farms or ranches?
Look what they found in the human nose
In 2019 and 2020, scientists at Boston University performed a small and simple experiment. They went to five dairy farms in the West and Southwest, and they washed the noses of workers before and after their shifts on the farm. They then looked for influenza D inside the laundry.
The researchers studied only 31 workers for 5 days. But they found quite a few viruses. “We found that about two-thirds of the participants were exposed to influenza D at some point during our study period,” said the environmental epidemiologist. Jessica Leibler, who led the study. Surname published Their findings in November in the journal Zoonoses.
While Leibler and colleagues tested only a small number of workers, the high percentage of those with the virus in their noses suggests that influenza D is most likely common on dairy farms in the Southwest. If the virus were rare on farms, it would be very unlikely to find such high levels by chance. “For me, the findings suggest that if you look for influenza D, you’ll probably find it,” she said.
Now Leibler and her team are only looking for exposure to influenza D. But previous studies have looked for signs of infection in cattle ranchers in Florida. Specifically, the study tested for influenza D antibodies in the blood of workers.
“They found a very high percentage of workers had influenza D antibodies,” says Leibler. “Again, this was a small study, but more than 90% of workers had antibodies to influenza D, which is what That means these workers are not only exposed, but also infected.”
In contrast, the prevalence of influenza D antibodies in non-farm workers was much lower. Researchers only have about 18% of the general population showing signs of being infected report inside Journal of Clinical Virology.
Currently, it is not known whether influenza D causes any symptoms in humans. But overall, these studies indicate that influenza D is likely to be called an emerging virus, Leibler said. It jumped on people who work with animals, such as dairy farmers, but it’s unlikely to spread beyond that.
“This doesn’t seem to be something, right now, that the general public is widely exposed to,” she said. “But that’s worrying for the frontline workers who work on the farms.”
That’s because there’s a real risk that the virus might adapt to humans as more and more workers become infected, she said. “Influenza viruses mutate rapidly and frequently. So over time, influenza D can evolve. It may increase its ability to infect humans and be more easily transmitted between people, or it may become more likely to become more contagious. more toxic” and start to make people sicker.
For that reason, Leibler and her colleagues are calling for more research and monitoring of this new flu to ensure the safety of dairy workers but also to ensure that the virus does not cause any harm. doubt for the world as SARS-CoV-2 did.
In fact, said Stephen Goldstein of the University of Utah, to prevent the next pandemic before it happens, scientists and officials should focus on the viruses that have already infected humans rather than feces. viruses in wild animals.
“Detecting viruses in wildlife is interesting scientifically, but from a pandemic prediction point of view, I think it’s a ridiculous concept,” he said. “Instead, we need surveillance – active surveillance – in humans and also in domestic animals.”
Currently, at least one company – Cambridge Technologies – is working on an influenza D vaccine for animals. But in general, very few farms look for the virus in animals or workers, says Jessica Liebler.
For comment on this topic, NPR reached out to the National Beef Association, the lobbying group for cattle ranchers. The spokesperson referred us to the United States Department of Agriculture. The USDA, along with the Centers for Disease Control and Prevention, said in an email that at this time there is no evidence that Influenza D is causing significant harm to pets, so there is currently no any monitoring system for livestock or workers.
As Liebler points out, officials and scientists have been on the same page about coronaviruses for a long time — that they’re not a big concern because they only cause colds.
“Sometimes an animal virus doesn’t seem to make people very sick and so scientists brush it off because it doesn’t really matter,” Leibler said. “That’s what scientists have thought about coronaviruses for a long time – that they’re not a big concern because they only cause colds.
“It only takes a major global pandemic for us to realize that viruses can change very quickly and you don’t know when they will change.”
