by Adrianna Rodriguez; Edited by News Gate Team
Health officials are still monitoring and controlling one of the biggest bird flu outbreaks in history, but the virus is starting to spread to mammals, including humans.
Although there are still very few human infections, according to medical professionals, it just takes one ideal set of mutations for the virus to spread widely among humans.
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The current state of bird flu and potential future developments are both fraught with uncertainty, according to Dr. Jay Varma, head of Cornell University’s Center for Pandemic Prevention and Response.
Is the world prepared in case avian influenza becomes the next human pandemic? This is what we do know.
Tracking avian influenza: How widespread is it?
Bird flu has been on officials’ radar since the late 1990s, health experts say.
The strains causing widespread outbreak now – avian influenza A (H5N1) 2.3.4.4b viruses – first arose in 2020 and spread via migratory birds to Africa, Asia and Europe, according to the World Health Organization.
In late 2021, the H5N1 strains crossed to North America. The U.S. Department of Agriculture reports over 58 million chickens have been affected in 47 states. Nearly 6,200 wild birds have been infected including eagles, hawks, geese and ducks, as of this week.
“It seems like it spreads very easily among different bird species. You have so many different bird species that die off so rapidly from it,” said Varma, who is also the chief medical adviser at Kroll, a risk consulting firm.
Health experts, however, are more concerned with how the virus is affecting mammals. The USDA has detected H5N1 in various animals all over the country including skunks, foxes, raccoons, bears, mountain lions and dolphins, among others.
Most of these infections appear to be individual cases where the animal may have gotten sick from eating an infected bird, experts say.
Mammalian transmission: Why experts are concerned
However, two instances of possible mammalian transmission have rung alarm bells for health experts.
Between June and mid-July, over 150 dead seals in Maine were attributed to the bird flu, according to the National Oceanic and Atmospheric Administration. Although it’s possible the seals could have eaten infected birds, health experts say the large number of dead seals and their proximity to one another suggests mammal-to-mammal transmission.
Another outbreak on a Spanish mink farm suggests the virus may have adapted to mammal transmission. Scientific investigators were called when minks began showing signs of infection including loss of appetite, hypersalivation, depression, bloody snout and tremors.
After swabbing two infected animals, they determined the rest of the sickened minks had bird flu. It’s unclear exactly how many minks were infected, but researchers noted the animals began dying a few days after exhibiting symptoms.
More than 51,000 minks were killed to prevent further spread. Post-mortem examination of infected minks found pneumonia in their lungs. This also sounded the alarm for health experts, who say a mink’s respiratory tract is closer to that of a human than bird.
“Ferrets, which are close relatives of mink, are our best animal model for human influenza infection,” said Stephen Morse, a professor epidemiology at Columbia University’s Mailman School of Public Health. “So, finding natural infection in mink seems a step closer to potentially infecting humans.”
After sequencing the offending strain, researchers discovered the H5N1 had a slight mutation that doesn’t exist in strain affecting birds. This “uncommon” mutation – T271A in the PB2 gene – was also seen in the swine flu H1N1 virus responsible for the 2009 pandemic that the CDC estimates caused more than 12,000 deaths in the U.S.
“We worry that this might be the prelude to the virus mutating in such a way that becomes a human epidemic,” Varma said.
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Can humans get bird flu? How does it spread to humans?
As of December, the WHO has reported six human infections from the circulating bird flu strains in China, Spain, the U.K., the U.S. and Vietnam.
All four cases in the U.S. and Europe were asymptomatic or mild infections, with fatigue reported as the only symptom. The patient in Vietnam developed severe disease but recovered, while the patient in China died.
“So far, the virus is difficult to transmit between people and the overwhelming majority of cases have been in people who have in direct and close contact with birds,” said Dr. Hana El Sahly, professor of molecular virology and microbiology at Baylor College of Medicine.
Bird flu tends to infect the lower respiratory tract, showing “it has a preference” in the lungs, said Dr. Katherine Baumgarten, medical director for infection control and prevention at Ochsner Health.
This suggests it could be less transmissible between humans because not as many viral particles are concentrated in the upper respiratory tract, like the nose or mouth, she said. But it also suggests the virus may be more capable of causing severe disease.
Can avian influenza cause a human pandemic?
Although researchers have identified certain mutations that may be associated with mammalian adaptation, health experts say these genes don’t seem to support widespread transmission between animals.
But that doesn’t mean it can’t happen. The more virus spreads, the more opportunities it gets to mutate and adapt.
“Flu viruses are always evolving, making them very unpredictable,” Morse said. “Could it spill over to the human population, and could it eventually become a pandemic? We really can’t say. It’s possible, but we don’t know how likely or, if it happens, when.”
Government agencies and international organizations track and study cases among birds, mammals and humans to detect any abnormalities that would be a cause for concern.
Health experts say it’s important to prepare for the possibility of an H5N1 pandemic because humans don’t have any immunity to the virus and it’s likely to cause severe disease.
Is the US ready for a bird flu pandemic?
The United States requires vaccines, treatments, and personal protective equipment in addition to surveillance, according to health experts.
The most popular antiviral drug for the seasonal flu in the United States is Tamiflu, but medical experts say it’s not certain if it will work against the H5N1 strains that are currently circulating.
According to a representative for the FDA, the Food and Drug Administration has authorized an H5N1 vaccine for those aged 18 to 64 who are at increased risk of exposure.
According to a Health and Human Services official, the nation has a limited quantity of vaccination. The vaccine can be used to scale up as necessary to match against strains with pandemic potential, which may take up to six months, according to medical experts.
According to the CDC, about 100 public health laboratories across the nation have tests that can find H5 viruses or new influenza A viruses.
A CDC official told USA TODAY that even in the absence of testing, the majority of commercial tests for the seasonal flu would be able to identify a new influenza A virus should an outbreak take place.
How to protect yourself against the bird flu
The CDC advises avoiding unprotected contact with wild or farmed birds that may appear sick or have passed away to prevent infection. If interaction is unavoidable, the agency advises:
wearing personal safety equipment, such as protective eyewear, boots, N95 masks, and disposable gloves.
When in contact with birds or infected surfaces, avoid touching your mouth, nose, or eyes.
Use soap and water to wash your hands.
After making contact, change your attire.
by Adrianna Rodriguez; Edited by News Gate Team
