Category: Flu Virus

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A ‘new normal’: Health officials, poultry farmers brace for likely …

April 9, 2023

Avian influenza showed up in Minnesota this year about 10 days later than last year, and experts say cases across the country are also growing at a slower rate this year.

One reason for that might be later than normal snow and ice delaying the early spring migration.

They seem to be kind of held out at the snow line, said Julianna Lenoch. National Coordinator for the USDA APHIS National Wildlife Disease Program. We've got some pretty spectacular videos coming in of snow geese and some other species that are just sort of stacking up in Nebraska because they can't get any further north right now.

But those early migrating geese aren't considered the prime carriers of the highly pathogenic H5N1 virus.

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It's those dabblers, your mallards, your pin tails, your blue winged, teal and green winged teal, those really seem to be the movers and shakers of this virus, said Bryan Richards, emerging disease coordinator with the US Geological Survey National Wildlife Health Center.

Migrating ducks return to the open waters at Purgatory Creek Park in Eden Prairie, Minn.

Photo courtesy of Douglas Fish

As those dabbling ducks migrated to Central and South America last fall there were corresponding new outbreaks of avian influenza in many countries. That means the virus remained active and widespread.

But the big question right now is what do our dabbling ducks bring back north with them? I think that's a really important question that will be answered very clearly over the course of the next six, eight weeks, something like that, as those dabblers head north, said Richards. If they're infected, if they're shedding virus, we'll know about it."

Richards will be watching for outbreaks in back yard poultry flocks as the first indicator of how prevalent and virulent the virus is this year. He encourages owners of backyard flocks to have a plan to protect their birds from exposure to wild birds.

Researchers with the U.S. Department of Agriculture have been tracking the virus in Central and South America.

Lenoch said its unclear if birds are adapting to the virus.

And that's really the kind of bang-for-the-buck question. What are they going to bring back with them? And are we going to see any possible immunity? she said.

The adult birds might have some immunity to the virus but could still spread it.

And wild ducks hatched this spring will be more vulnerable to the virus, perhaps helping to keep the outbreak going.

A turkey feather photographed near farmer Greg Langmo's barn in Litchfield, where about 11,000 turkeys died from avian influenza in 2015.

Jennifer Simonson | MPR News

Lenoch will be paying close attention to the effect on wild birds.

One of the big things is watching for any changes in wild bird morbidity and mortality, she said. So, are we going to see any large scale deaths or die offs in our wild bird populations.

Lenoch will also be closely watching reported cases in mammals. There's no national surveillance program to track the disease in mammals, she said, but states test possible cases.

USDA reported several red foxes and a skunk died from avian influenza last year in Minnesota.

Researchers are monitoring DNA changes in the virus found in mammals.

To keep a very, very close eye on any of those sequence changes that might indicate that the virus is any more dangerous to mammal populations. We really want to be watching that very closely, said Lenoch.

USDA will continue collecting DNA samples to help monitor the spread and any changes in the virus, always looking for connections.

So if a Mallard in say South Dakota, comes in and we do the sequence on it and then two or three weeks later we get a sick or dead fox or coyote, they'll compare the genetics of that animal to see how closely it matches," said Lenoch.

While it is helpful for the public to report sick or dead animals such as fox, skunks or coyotes, Lenoch said people should be cautious around sick or dead animals. Avian influenza in mammals can mimic symptoms of rabies or distemper.

We don't want any accidental exposure to any of the diseases. But particularly rabies is a very high concern because that is such a risk for human exposure. So if the general public were to see a sick animal, please don't touch it but, but call your local animal Control or Department of Natural Resources, Lenoch said.

A duck has a swab sample taken from its throat to be tested for avian influenza virus.

Dan Gunderson | MPR News

An avian virus moving to mammals brings it a step closer to being able to jump to humans. But the Centers for Disease Control and Prevention says the risk to humans is still low. There have been 11 humans cases worldwide since January of 2022. All were in people who handled infected poultry.

Bryan Richards has looked at cases of avian influenza in mammals and sees no evidence yet the virus is moving from animal to animal.

It looks like each one of these likely literally had a really bad last meal, he explained. They consumed the carcass of another animal, likely an avian, a bird that died from high path AI (avian influenza).

Lenoch and Richards both expect the virus to be strong again this year.

The waterfowl that carry the virus might be the best hope for slowing it. Waterfowl carry low pathogenic viruses that cause no illness. Richards says those common viruses will eventually mix with the virulent H5N1.

And so over time, we would anticipate that our low path viruses may overwhelm this highly pathogenic virus. And that's kind of our long term ticket out of this thing.

Thats what happened in the last big avian influenza outbreak in 2014-2015, said Richards.

But hes not making any predictions on how long it will take that to happen during this outbreak, and there's no evidence yet that the virus is losing strength.

A flock of 10-day-old poults, or young turkeys, about two weeks before they were ready to restock two central Minnesota turkey farms that were infected with avian influenza in 2022.

Courtesy of Matt Herdering

After more than 4 million bird deaths in Minnesota last year from avian flu, poultry farmers say they're working hard to avoid an outbreak, but also adjusting to living with the virus' presence.

Avian flu hit Pete Klaphake's central Minnesota turkey growing operation hard last year. In one just week, one of his farms tested positive on Monday, another on Tuesday. Within two days, they'd lost more than 100,000 birds.

After you have a positive, you go through, OK, where can where would we have had a breach? he said. Did we do something, or did something happen?

Klaphake doesn't have any clear answers. Maybe there was a breach in biosecurity, or the virus simply blew into his barns on a windy day.

By nature, I'm an eternal optimist, he said. So I'm hoping for our industry, I'm hoping for our operation, I'm hoping for the growers that work with us raising birds, that we don't have to deal with anything like we did last year.

The Minnesota Board of Animal Healths April 3 announcement of the first new case of bird flu in four months was news that poultry producers have been dreading.

We have definitely enjoyed kind of the lull in hyperactivity since December, but it doesn't mean that anybody's actually relaxed, said Ashley Kohls, executive director of the Minnesota Turkey Growers Association. Folks have definitely remained kind of on the edge of their seats.

While many Minnesotans are eagerly awaiting spring to melt the snow and ice, poultry producers are nervous for the warmer days that will bring migratory birds north, Kohls said.

Those wild birds can carry the virus to commercial poultry flocks, where it spreads quickly and is almost always lethal. The entire flock must be euthanized to prevent more infections.

Dr. Jill Nezworski, an independent poultry veterinarian, said the poultry industry is moving into a new normal, which includes living with high-path avian flu.

There's not a lot of optimism, she said. Everybody has the sense of impending dread of waiting for the outbreak.

George Parker sanitized semitruck tires at the Prinsburg Farmers Co-op, during the avian flu outbreak of 2015.

Mark Zdechlik | MPR News

The industry learned from last year's outbreak, Nezworski said. Farmers stuck to biosecurity plans to prevent the disease from spreading from farm to farm, such as limiting visitors, and sanitizing trucks and equipment.

But Nezworski said data show the majority of outbreaks last year appear to have been so-called independent introductions. So, more than ever, farmers are looking at how to prevent the virus from entering the barn from outside, she said.

We're all taught how to prevent farm-to-farm spread. That's much more traditional biosecurity practices, Nezworski said. In this new normal, we have to get really creative.

Some poultry farmers are applying calcium chloride to gravel roads, to reduce dust that might blow into barns, she said. Others are taking extreme measures to keep away wild birds that could carry disease. That includes installing systems that scare them away by shining laser beams.

Nezworski said others are trying air horns, fake coyotes, or even giant inflatable air dancers with flailing arms commonly seen at car dealerships.

I have one grower who's got a stack of bottle rockets that he's shooting off to scare the geese away, she said.

Other producers say they're not rushing to adopt any new prevention methods, but are sticking to practices that have worked in the past. That includes Erica Sawatzke, a sixth-generation turkey farmer in Kensington, west of Alexandria.

We've always tried to be diligent about keeping wild birds away, even rodents out of our barn, because they'll track in diseases, Sawatzke said. So for us, that's something that we've never changed on our farm.

Federal scientists have been working on a poultry vaccine to prevent bird flu. But there's still debate over how and when it might be used, driven in part by fears of trade restrictions that it could hurt poultry exports. In any case, mass vaccinations are unlikely to happen in time to prevent an outbreak this year.

Roy Schneider passes through a shoe wash at the Gold'n Plump offices in Sauk Rapids, Minn. on Dec. 2.

Jackson Forderer for MPR News | 2015

Despite the stress and financial strain that avian flu brings, many poultry growers say theyre not thinking of calling it quits. But learning to deal with the threat of a contagious virus is now part of the job.

I would expect that there's some producers that are nervous, Sawatzke said. But I think probably there are some that are realistic, too, and that this is something that we're going to have to learn to live with.

Klaphake said they're not letting down their guard, and are doing what they can to prevent an outbreak. He tries not to spend too much time dwelling on the what-ifs.

If you're constantly worrying about about disaster happening in any walk of life, you're not going to do that occupation very long, he said.

Lab technician Jessica Spanier process reports at the Minnesota Poultry Testing Laboratory in Willmar, Minn., in April.

Paul Middlestaedt for MPR News

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A 'new normal': Health officials, poultry farmers brace for likely ...

The effectiveness of seasonal influenza vaccine against h3n2 influenza …

April 9, 2023

H3N2 VIRUS is a non-human influenza virus that normally circulates in pigs and that has infected humans.Influenza A (H3N3) is responsible for present rise in flu cases as notified by ICMR. Both H1N1 and H3N2 sub-types are variants if influenza A which change genetically as well as antigenically to produce new variants. H3N2 tends to change more rapidly, both genetically and antigenically, compared to H1N1. H3N2 is the cause behind rise in flu case that we have been seeing recently.

Influenza ( H3N2) pandemic was first reported in 1968 in the USA for the first time and recently in the year 2011 and again 2020-21.Influenza viruses can spread from pigs to people and from people to pigs. Spread from infected pigs to humans is thought to happen in the same way that seasonal influenza viruses spread between people; mainly through infected droplets created when an infected pig coughs or sneezes.

The symptoms of H3N2 virus are similar to other respiratory viruses, including fever, sore throat, nasal discharge, headache, coughing, myalgia, and nasal discharge. In severe cases, pneumonia and bronchitis could happen, which can lead to death.

As we know that there is no targeted therapy for most of the viral infections and specially for flu it is symptomatic therapy that is advised for patients. Oral anti virals like osaltamavir , zanamivir, peramivir can be used . Preventive measures like using masks, frequent hand wash, cough etiquette and self isolation are recommended to minimise the risk of disease transmission to other members in the community.

There is no specific vaccine for h3n2 variant of influenza A virus but research to develop a vaccine has started. A pilot H3N2 virus vaccine was produced and preliminary clinical studies indicated that it leads to a significant immune response.Seasonal flu vaccine will not protect against H3N2v. Seasonal flu vaccines protect against seasonal influenza viruses. CDC recommends that everyone 6 months and older get a seasonal flu vaccine each year. Many types of seasonal influenza vaccines are available in the market and a new strain vaccine is produced every year according to the change that happens due to antigenic drift in the virus.

Vaccines are advised and are helpful in preventing serious form of the illness. Influenza vaccines, though, generally have variable and only moderate efficacy; they remain a critical preventive strategy for controlling the disease and its consequences. The egg-based quadrivalent vaccines have been recommended as they give protection to both influenza A and B variants.

In the case of influenza, effectiveness is expected to be lower than the efficacy ( reduction in risk of a disease in a given condition )because it is measured using the rates of influenza-like illness, which is not always caused by influenza. Studies on the effectiveness of flu vaccines in the real world are difficult due to many reasons vaccines and also because influenza is often confused with other influenza-like illnesses. However, most of the times the flu vaccine strains have been a good match for the circulating strains and even a mismatched vaccine can often provide cross-protection.

The effectiveness of seasonal flu vaccines varies significantly, with an estimated average efficacy of 50-60% against symptomatic disease, depending on vaccine strain, age, prior immunity, and immune function.

Though vaccinated people can still contract influenza, The effectiveness of flu vaccines particularly among the elderly and immunocompromised is still beneficial in reducing the mortality rate and hospitalization rate due to influenza as well as duration of hospitalization stay. Vaccination of school-age children has shown to provide indirect protection for other age groups as well.

Considering the point that seasonal flu vaccine reduced chances of serious illness and complication leading to hospitalization and even death in certain cases it is advised to take a flu shot. Especially immunocompromised and elderly people above 65 years are recommended to take the vaccine annually.

Views expressed above are the author's own.

END OF ARTICLE

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The effectiveness of seasonal influenza vaccine against h3n2 influenza ...

Quick takes: US RSV seasonality, CDC Marburg virus alert, US flu update …

April 8, 2023

The rate of US newborns with maternal-transmitted COVID-19 was five times higher during Omicron variant predominance than before, according to a study led by researchers at the Centers for Disease Control and Prevention (CDC).

In the study, published today in Pediatrics, the researchers parsed data on infants aged 0 to 6 months born to COVID-infected mothers in 2020 or 2021 in six US jurisdictions reporting data to the CDC's Surveillance for Emerging Threats to Pregnant People and Infants Network.

Massachusetts, Minnesota, Missouri, Puerto Rico, Tennessee, and Philadelphia reported cases before (March 22, 2020, to December 18, 2021) and during (December 19, 2021, to September 9, 2022) Omicron predominance.

Before Omicron predominance, 27,403 infants were born to mothers who tested positive for COVID-19 (rate, 3.1 per 100 person-years). During the Omicron wave, 14,115 infants tested positive for COVID-19 (rate, 15.3 per 100 person-years; incidence rate ratio [IRR], 5.00).

The proportion of infants infected within 14 days after delivery by mothers infected within 14 days before delivery fell from 31.4% before to 0.8% during Omicron predominance, which the researchers said suggests that the higher rate of infection during Omicron wasn't caused by increased perinatal transmission.

In a subanalysis limited to infants born to infected mothers pre-Omicron, the IRR rose to 5.83. "This finding aligns with other evidence of reduced protection against Omicron from previous infection with other variants," the authors wrote. "Increased transmissibility of the Omicron variant to infants who are ineligible to receive COVID-19 vaccination, raises the importance of preventing SARS-CoV-2 transmission through other means, such as vaccination of pregnant and postpartum people."

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Quick takes: US RSV seasonality, CDC Marburg virus alert, US flu update ...

This common hand hygiene mistake can spread stomach flu as cases …

April 6, 2023

As this winter's tripledemic respiratory virus surge winds down and gives way to allergy season, some doctors are cautioning about another highly contagious virus spreading across the United States and sickening children: norovirus.

Cases and outbreaks of the notorious wintertime stomach bug have been steadily rising in the U.S. since last fall, more recently spiking and reaching new highs for this season, according to the most recent surveillance data from the U.S. Centers for Disease Control and Prevention.

Norovirus commonly known as the stomach flu is actually a group of viruses that cause acute gastroenteritis, an inflammation of the lining of the stomach and intestines, which leads to acute vomiting and diarrhea, per the CDC. Unlike its nickname suggests, norovirus is not related to the flu or influenza viruses.

In the U.S., the percentage of norovirus tests coming back positive, averaged over three weeks, was over 18% for the week ending on March 25, which surpasses last year's peak, according to the most recent data from the CDC'sNational Respiratory and Enteric Virus Surveillance System (NREVSS).

Outbreaks of norovirus are also on the rise in the 14 states reporting data to CDCs NoroSTAT program, Kate Grusich, CDC spokesperson, tells TODAY.com in a statement.

"The most recent CDC data ....show that reported cases from state health departments and clinical laboratories are increasing, but still remain within the expected range for this time of year," Grusich says, adding that the U.S. typically sees about 2,500 outbreaks per year.

However, some experts tell TODAY.com they're still bracing for norovirus outbreaks, especially among school-age children.

In late March, hundreds of children at a high school in Long Island, New York, were out sick with what officials believe was norovirus linked to an outbreak at a school dance, NBC New York reported.

Charlottesville, Virginia, is also facing a norovirus outbreak, local outlet NBC 28 reported.

The situation across the pond doesn't ease concerns either. Earlier this month, health officials in England warned that norovirus cases had reached the highest levels for this time of year in over a decade. In mid-March, reports of norovirus were 77% higher than the five-season average during the same period, according to the U.K. Health Security Agency.

So what can we expect for spring in the U.S.? We spoke to experts about how this year's norovirus season may compare to others and what you need to know about symptoms, transmission, treatment and prevention.

Norovirus outbreaks are common in the U.S., says Grusich. Each year, norovirus causes 19 to 21 million cases of vomiting and diarrhea, 109,000 hospitalizations and 900 deaths, per the CDC.

Although norovirus can spread year-round, it has a wintertime seasonality in the U.S., says Grusich, so cases tend to peak during the colder months. The vast majority of outbreaks occur between November and April, according to the CDC.

While it is too early to tell exactly when exactly norovirus will peak in the U.S. and how the 2022-2023 will compare to prepandemic seasons, it is clear that cases and outbreaks are rising right now.

Its going up quickly right now. Its not yet at the peak weve seen in previous years, but its definitely on the rise and pretty suddenly in the past few weeks," Dr. Ali Alhassani, a pediatrician at Boston Childrens Hospital and head of clinical at Summer Health,tells TODAY.com.

A surge in norovirus outbreaks could lead to an increased number of emergency room visits, Alhassani notes, or a reduction in the already-strained health workforce.

Dr. Luis Ostrosky, an infectious disease specialist at UTHealth Houston and Memorial Hermann in Houston, tells TODAY.com that norovirus activity is higher and earlier than usual (right now), but definitely not a big outlier compared to pre-pandemic levels.

Children who managed to evade the virus over the past few years are now being exposed to norovirus and many other viruses that tend to peak and circulate among schools at this time of year.

"We've always had seasonal increases and waves of norovirus, and our hospitals would be filled with kids," Dr. Albert Ko, infectious disease physician and professor of public health, epidemiology and medicine at Yale School of Public Health, tells TODAY.com. "What kind of took us off was the pandemic," Ko adds.

Prevention measures implemented to curb COVID-19 were likely effective in preventing norovirus outbreaks, says Grusich, and as restrictions have relaxed, the number of outbreaks has returned to levels similar to pre-pandemic years.

This is certainly higher than what we experienced during COVID, but its in the order of what we saw prior to the pandemic, give or take theres variation year to year, says Ko.

While the jump in the norovirus test positivity is concerning, Ko says, it is not unexpected. I would be surprised if this years peak is worse than last years. ... I think were going to be starting to get back to the epidemiological pattern that we normally see, says Ko.

The same virus strains that circulate in the U.S. are often what surges in Europe, says Alhassani. Although cases are starting to level off in England, Ko notes, it's still unclear whether this record surge is a harbinger of how severe norovirus will get in the U.S.

Norovirus is transmitted primarily "when bacteria or viruses shed in stool ends up on our hands and surfaces and then eventually ends up in our mouth and we ingest it and get infected," says Alhassani.

Norovirus may be transmitted directly from an infected person or from contaminated surfaces, objects, foods or drinks.

"Anybody who is in close contact with someone who has an active infection with norovirus is at high risk of getting it," says Alhassani. Norovirus can spread through activities like caring for an infected person, changing diapers or sharing utensils.

"Norovirus is so infectious that even if somebody throws up and there's droplets of vomit aerosolized in the air, that can actually cause infection," Alhassani adds.

It takes a very small number of virus particles to transmit the disease, says Ko, which is why norovirus causes so many explosive outbreaks. Per the CDC, less than 100 norovirus particles can make you sick, and infected people typically shed billions of particles.

Most people are infectious from the time symptoms begin until about two or three days after symptoms resolve, Ko says, but some people can remain contagious or up to two weeks after recovery.

Outbreaks often occur in schools, day cares, nursing homes and cruise ships, the experts note.

The most common symptoms of norovirus are vomiting, nausea, diarrhea and abdominal pain, says Ko. Other possible symptoms include a headache, body aches and a low-grade fever. Norovirus symptoms usually develop within 12 to 48 hours after exposure, per the CDC.

"Norovirus ... will just last a few days," says Ostrosky. "For the majority of the population, its going to be just a nuisance."

Those at higher risk of developing severe or prolonged symptoms include babies, the elderly and the immunocompromised, says Ostrosky. If symptoms transition into chronic diarrhea and weight loss, this can lead to complications like dehydration or poor absorption of medications, he adds.

"There's actually no specific treatment or antiviral for norovirus," says Ostrosky. Hydration is key to replenish fluids lost from vomiting and diarrhea, the experts note, which means drinking plenty of water, Pedialyte or sports drinks.

"Then it's just eating bland foods and trying to let it pass through the body, which usually takes like one to three days," says Alhassani, adding that over-the-counter anti-nausea medicine and pain relievers may also be used to ease symptoms.

The vast majority of people can be managed at home and, in fact, should be isolated at home until theyre improving, given how contagious norovirus can be, says Ostrosky.

However, it's important to watch for signs of severe dehydration and to contact a health care provider if these occur, the experts note. These include dry mouth, decreased urination, dizziness and, in children specifically, crying without tears, fussiness or unusual sleepiness, per the CDC.

Children under 1, people who are immunocompromised, or those with prolonged or severe symptoms should also be seen by a physician, says Alhassani. While it infects many people, (norovirus) tends to not send as many people into the hospital and certainly the ICU, he adds.

A person can be infected with norovirus multiple times in their lifetime. After recovering, you may possibly develop some short-term immunity, says Ko, but it won't be robust and it wanes quickly.

It's only partial immunity ... because there are different types of norovirus, and being exposed to one doesnt give you complete protection to another, he says.

There's no vaccine against norovirus, says Ko, but there are steps you can take to prevent infection and transmission.

Hand hygiene is extremely important but the way you clean your hands matters, Ostrosky notes, and it has to be with soap and water. Hand sanitizer does not work against norovirus.

Norovirus is one of the few viruses that doesnt get deactivated by alcohol. You actually need to use soap and water to physically destroy it and remove it from your hands, says Ostrosky.

Wash your hands after using the restroom, before eating or cooking and after caring for someone with norovirus.

When cleaning surfaces or objects that may be contaminated with norovirus, Ostrosky suggests using a high-level disinfectant like bleach.

If you or your child are sick with norovirus, isolate to prevent the virus from spreading within the household, says Alhassani. Anyone sick with norovirus should stay home until they feel better. Avoid food preparation until at least 48 hours after symptoms stop, says Grusich.

"We can expect to continue seeing more viral illnesses, both respiratory and gastrointestinal, in this post-COVID era we're sort of approaching," says Ostrosky, adding that the basics of hand-washing, isolation and respiratory etiquette can go a long way.

This article was originally published on TODAY.com

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This common hand hygiene mistake can spread stomach flu as cases ...

A new flu is spilling over from cows in the U.S. How worried should we …

April 6, 2023

In 2011, a farmer in Oklahoma had a bunch of sick pigs. The animals had what looked like the flu.

"Just like a person with respiratory disease, the pigs had labored breathing, maybe a runny nose, cough and potentially a fever," says virologist Benjamin Hause.

At the time, Hause was working at the company Newport Laboratories, which develops custom vaccines for livestock. "We would detect and isolate pathogens from animals. Then we would grow the pathogens in the lab, kill them and formulate vaccines," says Hause, who's now an executive at Cambridge Technologies, another vaccine company.

The Oklahoma farmer took a few samples from the pigs' noses a bit like how you swab your nose for an at-home COVID test. He sent the samples to Hause so he could figure out what was making the pigs sick.

Hidden viruses: how pandemics really begin

NPR is running a series on spillover viruses that's when animal pathogens jump into people. Researchers used to think spillovers were rare. Now it is clear they happen all the time. That has changed how scientists look for new deadly viruses. To learn more, we traveled to Guatemala and Bangladesh, to Borneo and South Africa.

Hause immediately thought that the regular flu virus was infecting the pigs. "We expected to find influenza A," he says, "because that's the most common problem." It's also the same type of virus that often causes the seasonal flu in people.

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 thing? We've never seen anything like this before,' " he says. "Right away, we were concerned that this virus could infect people."

For decades, scientists thought that animal viruses seldom jump into people. They thought these spillovers were extremely rare. But in the past few years, studies have been showing that this thinking is wrong.

"I don't think [spillover] is extremely rare," says evolutionary virologist Stephen Goldstein at the University of Utah. "I mean, we know this because when people start looking, people find it."

In fact, there's likely a whole group of animal viruses making people sick all over the world that doctors know nothing about. They've been hidden. They masquerade as a regular cold, flu or even pneumonia.

For example, if you have a respiratory infection in the U.S., doctors can identify the pathogen causing the infection only about 40% of the time. There's growing evidence that the other 60% of infections could be caused by animal viruses such as a dog coronavirus found in Malaysia, Haiti and Arkansas, or even possibly the same virus Hause and his colleagues found in those pigs. Recent studies have made clear that this virus floats in the air at farms and is likely infecting people who work there.

Hause and his colleagues eventually figured out that they had stumbled upon an entirely new influenza virus, unrelated to the ones known to infect people. "It's completely different than influenza A," says virologist Feng Li at the University of Kentucky, who co-led the discovery of the new virus.

Once scientists started looking for signs of infections in other animals, besides pigs, they found it nearly everywhere they looked: in sheep, goats, camels, horses.

But Li says they hit the jackpot when they looked in one particular animal: cows.

"The percentage of cows in the U.S. that have antibodies to influenza D is way, way high," he says. "Whenever you look at herds, about 50% of individual cows have high levels of antibodies to this virus. That was really surprising."

And it's not just cows in Oklahoma but across the whole country, from west to east and north to south, Li says. "From California to Vermont, and North Dakota to Texas, cows are infected with this virus. They are the primary reservoir for the virus."

On top of that, this virus is incredibly stable, Li says. "It can survive at high temperatures and in acidic environments," he says. "That's why scientists have found influenza D in the air at airports in the U.S." They've also found it in the air at chicken farms in Malaysia.

And so the question has become: If this virus can infect so many different animals and is found in so many cows, does it make people sick? Especially the people who work closely with cows on dairy farms or ranches?

In 2019 and 2020, scientists at Boston University ran a small and simple experiment. They went to five dairy farms in the West and Southwest, and they washed out the workers' noses before and after their shifts working on the farms. Then they looked for influenza D inside the washes.

The researchers studied only 31 workers over the course of only five days. But they found quite a lot of the virus. "We found about two-thirds of the participants were exposed to influenza D at some point during our study period," says environmental epidemiologist Jessica Leibler, who led the study. They published their findings in November in the journal Zoonoses.

While Leibler and colleagues tested only a small number of workers, the high percentage who had the virus in their noses suggests that influenza D is quite likely common on dairy farms in the Southwest. If the virus was rare on the farms, then finding it at such high levels by chance would be highly unlikely. "To me, the findings suggest that if you look for influenza D, you probably will find it," she says.

Now Leibler and her team looked only for an exposure to influenza D. But previous studies have looked for signs of infections in cattle workers in Florida. Specifically, the study tested for influenza D antibodies in the workers' blood.

"They found a really, really high percentage of workers with influenza D antibodies," Leibler says. "Again, it was again a small study, but more than 90% of the workers had antibodies to influenza D, which implies these workers weren't only exposed, but they were also infected."

In contrast, the prevalence of influenza D antibodies in people who don't work on farms was much lower. Only about 18% of the general population showed signs of being infected, researchers reported in the Journal of Clinical Virology.

Now, no one knows yet if influenza D causes any symptoms in people. But altogether, these studies indicate influenza D is likely what's called an emerging virus, Leibler says. It's jumping into people who work with animals, such as dairy farmers, but it's not likely spreading much beyond that.

"This doesn't seem to be something, right now, that the general public is exposed to in a large way," she says. "But it's something that's a concern for these front-line workers exposed on farms."

That's because there's a real risk that the virus could adapt to people as more and more workers are infected, she says. "Influenza viruses mutate rapidly and frequently. So, over time, influenza D can evolve. It could increase its ability to infect humans and be more easily transmitted among humans or it could become more virulent" and start making people sicker.

For that reason, Leibler and her colleagues are calling for more research on, and surveillance of, this new flu to ensure the safety of the dairy workers but also to ensure that the virus doesn't surprise the world as SARS-CoV-2 did.

In fact, Stephen Goldstein of the University of Utah says, to stop the next pandemic before it occurs, scientists and officials should focus on these viruses that have already made the jump into people instead of cataloging viruses in wild animals.

"Doing virus discovery in wild animals is interesting from a scientific standpoint, but from the standpoint of predicting pandemics, I think it's a ridiculous concept," he says. "Instead we need surveillance active surveillance in humans and also in domestic animals."

Currently, at least one company Cambridge Technologies is working on a vaccine against influenza D for animals. But in general, very few farms are looking out for the virus in animals or workers, Jessica Leibler says.

For comments on this topic, NPR reached out to the National Cattlemen's Beef Association, the lobbying group for cattle ranchers. A spokesperson referred us to the U.S. Department of Agriculture. The USDA, along with the Centers for Disease Control and Prevention, said in emails that, at this point, there isn't any evidence that Influenza D is causing significant harm to livestock, so there aren't currently any surveillance systems in place for livestock or workers.

As Leibler points out, officials and scientists had a similar view of coronaviruses for a long time that they weren't a major concern because they only caused a cold.

"Sometimes an animal virus doesn't seem to make people very sick and so scientists brush it away as not really important," Leibler says. "That's what scientists thought about coronaviruses for a long time that they weren't a major concern because they only caused a cold.

"It only took a huge global pandemic to realize that viruses can change really quickly, and you don't know when they're going to change."

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A new flu is spilling over from cows in the U.S. How worried should we ...

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