Avian flu FAQ: H5N1 dairy outbreak in Texas, New Mexico, Michigan

The good news is that—at least for now—public health experts don’t see this latest wave of bird flu evolving into these forms. pandemic caused by coronavirus. But because the disease has spread to poultry in 48 states, dairy cows in nine states, and two each in Texas and Colorado, you may be worried about its potential impact on your health.

Luck spoke with a trio of epidemiologists, who below answer important public health questions about Avian flu.

What is bird flu?

The type of bird flu currently circulating is one type Highly pathogenic avian influenza (HPAI)—a disease that can cause serious illness in wild and farmed birds, posing a major threat to the poultry industry and thus the global economy, according to United States Department of Agriculture (USDA). The other type is low pathogenic avian influenza, which causes mild disease in wild poultry but can transform into HPAI in poultry.

Influenza virus divided into 4 types A, B, C and D, explained Edwin Michael, Ph.Dan epidemiologist at South Florida College of Public Health. What we think of as seasonal flu in humans is caused by types A and B. Avian flu is a type A influenza virus. The strain currently spreading in the US is H5N1, a type of HPAI named after the protein on the surface of the virus.

“It can spread very quickly through bird populations—wild birds. That could spread around the world,” Michael said Luck. “From poultry, the virus is released through mucus, saliva, and feces, which can then enter farmed poultry.”

When HPAI strains get into domestic poultry, they can kill entire flocks within days, according to the USDA. Birds infected with HPAI can exhibit a range of symptoms including diarrhea, lack of energy and appetite, and reduced egg production. Since HPAI cannot be treated, reducing poultry numbers is the only solution.

Such culling could be effective in limiting the spread of bird species important to U.S. agriculture and food production. Dr. William Schaffnera professor in Division of Infectious Diseases at Vanderbilt University Medical Center.

“This particular bird flu virus, with its variants, has actually been around for a long time — more than a decade,” Schaffner said. Luck. “It was gradually spreading but recently, somehow, for reasons that I at least don’t understand, its spread around the world has become much more obvious and much more widespread.”

DIGITAL/SCIENTIFIC PHOTO GALLERY VIA GETTY IMAGES

How does bird flu spread to humans and other mammals?

H5N1 is a shapeshifter, Michael explains, due to its fragmented DNA, so to speak.

“For example, if a person is infected with avian influenza and also carries the human influenza A virus, the two viruses can exchange genetic material. This is called genetic change“Michael said. “That could form very new viruses [and] cause epidemics.”

However, flu pandemics are rare, occurring about three times a century, Michael said. Perhaps most notable is the so-called “Spanish Flu” of 1918–1919when the Centers for Disease Control and Prevention (CDC) estimated “an avian-like H1N1 virus” had killed 50 million people and possibly as many as 100 million worldwide.

Surely you remember swine flu pandemic of 2009, caused by a previously unknown H1N1 virus that contains swine, human and poultry genes. How did that happen? Because avian flu viruses don’t always spread effectively in humans, they sometimes need help from other species to thrive, Schaffner explains.

“The pig’s respiratory tract is set up so that it can tolerate avian influenza infection and—And—viral infection in humans,” Schaffner said. “You can think of the pig as a test tube of avian flu and human flu, and if that happens at the same time in the same pig, those two viruses will combine and could potentially exchange. change genetic factors.”

Although the latest H5N1 strain has not yet spread to humans, it has spread to more than a dozen wild mammals, from black bears to bottlenose dolphins. Most recently on May 3, red foxes in New York and Michigan tested positive, according to the agency. USDA’s Animal and Plant Health Inspection Service (APHIS)..

“This avian influenza virus does not depend on pigs but mutates to become a virus that more effectively infects many different mammals,” Schaffner said. “The type reported is a dairy cow, which surprised every virologist.”

When did bird flu last appear in the US?

Government agencies have supervised the work Latest bird flu epidemic as of January 12, 2022, when a Northern Shovel ducks in Hyde County, North Carolina, tested positive for the Eurasian H5N1 strain.

In wild birds, the disease has spread everywhere more than 1,100 districts As of May 8, 2024, it has infected nearly 9,400 poultry.

The situation is even worse American poultry. As of May 7, nearly 91 million birds, incl commercial poultry and backyard flocks, was infected. This includes more than 1,100 outbreaks in 522 counties across 48 states.

APHIS recorded poultry infection for the first time in a commercial turkey flock in Dubois County, Indiana, on February 8, 2022.

Although H5N1 has spread nationwide in wild birds, poultry and mammals since 2022, you may have only heard about it recently because of its nature. switch to dairy farming. The first positive case was recorded in Texas on March 25, 2024.

As of May 7, nearly 40 herds of dairy cows have been destroyed. infected across nine states.

The logistics of modern industrial agriculture may have fueled the spread of H5N1 to livestock, Michael said.

“Look at the density of animals on those farms — it’s not a natural environment,” Michael said. Luck. “So as soon as you get it [an infection]These will spread very quickly among farm animals.”

“We have to demystify how farming is done,” adds Michael. It’s a trade-off, you want cheap meat and all that, but then you raise livestock this way and you’re opening the door for other things.”

Is it safe to drink milk and eat chicken?

The Food and Drug Administration (FDA) acknowledges the presence of avian influenza in dairy cattle as “a new and evolving situation”. That said, no previous studies have been conducted on the effects of pasteurization—a sterilization practice that kills harmful bacteria—on HPAI in cow’s milk. However, the FDA says current research provides insight and concludes that consuming milk is safe.

FDA and USDA are conducting a national commercial milk sampling study, including milk-based infant formula. As of May 1, no HPAI had been detected in any formula products. While avian influenza was present in samples of milk, sour cream and cheese, pasteurization inactivated the virus.

“No need to worry about milk, eggs, [and] chickens are the source of infection,” Schaffner said Luck. “I was out there drinking milk and we ate chicken last night.”

Both Schaffner and the FDA urge the public to stay away from raw, unpasteurized milk. CDC recommends Cook eggs and poultry to an internal temperature of 165 degrees to kill bacteria and viruses, including H5N1.

How worried should you be about H5N1 affecting people?

Simply put, don’t panic, say Michael Osterholm, Ph.DDirector of Center for Infectious Disease Research and Policy at the University of Minnesota.

“At this time, there is no evidence that this is an imminent risk to humans,” Osterholm said. Luck. “We have not seen it spread to humans in a way that would demonstrate that it will become the next pandemic virus.

“On the other hand, a reclassification event or continued mutations could occur tomorrow.”

According to the CDC, two people have been infected with H5N1 so far. A person exposed to dairy cows in Texas tested positive on April 1, 2024 and one person in Colorado participates in poultry culling tested positive on April 28, 2022. No human-to-human transmission has been confirmed and the patient’s only recent symptom was conjunctivitis or pink eye.

“We have two or three receptor sites in the eye, and so having conjunctivitis would not be considered unusual,” Osterholm says. “There is no evidence of any type of respiratory infection, which is a major cause of severe illness and subsequent transmission of the virus.”

The Texas incident marks the first time a person has been infected with H5N1 through contact with a mammal. World Health Organization (WHO). Despite this, WHO considers the public health risk to the general population to be low. For farmworkers and other industry employees potentially exposed to the virus, the risk is low to moderate.

Michael said going forward, ensuring the health and safety of agricultural workers will be paramount to preventing H5N1 from spreading to the wider population.

“I don’t think this outbreak will become a major outbreak (in humans),” Michael said. “[But] Risk is always present because of the way we manage nature.”

To know more about the latest bird flu outbreak: