COMMENTARY·
HEALTH
No one wants another pandemic—but bird flu has already flown the coop
BY Carolyn
BARBER
June 11, 2024 at 11:57 am
At first glance, some of the expert reactions to the recent surge in bird flu virus cases, both in the U.S. and around the world, may appear contradictory. Isn’t a more urgent response required? How much livestock will be sacrificed? Is the risk to humans really so low that only moderate actions are called for?
In truth, though, most of the basics are no longer in question among epidemiologists. This H5N1 virus is certainly spreading. Thousands of
outbreaks have been documented in wild and farmed bird populations across all continents, spilling over into
mammal populations. In the U.S. alone, bird flu has resulted in the death of more than
96 million birdsin commercial and backyard flocks since February 2022, according to a
USDA database.
‘The virus has proven its versatility’
Since 1997, sporadic H5N1 infections have been reported in humans in
24 countries, though relatively
few cases were reported in recent years
. After only one case in the U.S. in the previous 25 years, three farmworkers here have become infected over the past two months.
So where do we go from here? That depends significantly, the experts say, on whether …
“I would like to see very widespread serologic testing done in humans—the farm workers, their family members, contacts,” says epidemiologist Michael Osterholm, director of the Center for Infectious Disease Research and Policy. (Serologic testing looks for antibodies in the blood.) “That way, we can see if we’ve had more transmission in humans that we’ve missed. We don’t have that right now.”
“There are just so many things we don’t know, and it’s the unknowns that concern us more than what we know so far,” says Rick Bright, a virologist, pandemic expert, and former head of the U.S. Biomedical Advanced Research and Development …,
…The virus has now been confirmed in cows in
more than 85 herds with as many as 12 states affected. This geographic spread, along with high levels of exposure by workers at farms, slaughterhouses, milk processing facilities, and milk itself, is part of what has experts concerned that the virus will be found in more people. The Centers for Disease Control (CDC) has warned against drinking
unpasteurized raw milk, which the CDC says may contain the H5N1 virus.
“The virus has proven its versatility to infect about any mammal it comes in contact with,” says Bright.
…..
“When you have a bird flu virus infecting mammal species, that raises the question of the virus becoming more adaptive for mammalian transmission,” says Amesh Adalja, a senior scholar at the Johns Hopkins Center for Health Security. “There are distinct barriers that bird flu viruses face when they’re infecting mammals in terms of which receptors they use. So that has raised the stakes……
The respiratory piece concerns health experts because someone with H5N1 virus in their airways could be more likely to spread the virus, perhaps via cough. To date, there’s been no evidence of human-to-human transmission of H5N1 virus, and the CDC
says the current health risk to the general public is low. But as CDC Principal Deputy Director Nirav Shah noted at a Council on Foreign Relations
eventin May, “The risk here of something going from one or two sporadic [human] cases to becoming something of international concern (is) not insignificant…..
…
Reuters recently reported that dairy cows in five states have
died or been slaughtered-because they did not recover from their infections, though the USDA says the majority-of cows do recover
. Should infection among cattle become more widespread, the potential cost to American farms is astronomical, as cows cost much more than chickens or turkeys to raise—ironically, one reason farmers may be reluctant to test them.
“What we’re seeing right now in dairy cattle is just another situation where the potential for that virus to change is, I think, surely increased,” Osterholm says. The rise in severe illness among many of the species who’ve been infected by H5N1 is concerning, he notes, partly because it isn’t clear exactly why that has happened. “If you look at genetic sequences and look what the virus has done, we can’t explain that any one mutation has caused this to happen.”
‘We’re just sort of letting it go and spreading it in a very naive way’
The CDC recently
confirmed the lethality of the H5N1 virus, isolated from a human infection in Texas, in ferrets that were experimentally infected with the same virus. All of …..
Osterholm and others are advocating for increased urgency on the testing front. This is a multifaceted ask; it includes more widespread and continuous testing of farm animals, workers, and their close contacts—and in the case of dairy herds, ongoing testing of the milk supply and any meat that is directed to the food supply for human or animal consumption.
It’s important to also test the farm environment, including equipment, transport vehicles, milking machines, and water systems that may be contaminated by disposal of infected milk. Raw milk from cows infected with bird flu has been found to contain
astounding amounts of viral particles, according to a non-peer-reviewed study. (The FDA says our commercial supply of
pasteurized milk remains safe to ……
“We’re not stopping it,” says Bright. “We’re not doing anything to keep that infected milk and infectious milk on the farm. We’re not testing these cows before they’re put back onto the milking line or sent to slaughter…We’re just sort of letting it go and spreading it in a very naive way.”
At almost every turn, there are complications. Absent a federal mandate, most of the testing being done is voluntary. A USDA spokesman told me the agency provides voluntary testing and monitoring options, and has a program that reimburses dairy producers for collecting samples. But, Bright says, “we are finding that many farms don’t want to test because they are afraid that they’ll be shut down or suffer a significant economic loss that is not yet being compensated by federal programs.”
……As of June 7, the CDC reported that only
45 people had been tested-nationwide since March.
A proactive testing and surveillance program would make rapid flu testing available at all farms, Adalja says. (Specific H5N1 tests don’t yet exist.) “We would be randomly testing cows all over, not just ones that appeared sick or ones that are transported from one state to another,” he adds. And experts have suggested pooled testing of milk from more cows on each farm in an effort to detect infected cows that might not show outward signs of infection.
Sharing data
quickly from cases of infected animals and people is critical, too, experts say. “The USDA is refusing to share the sequence data from the cows and the animals in a timely manner,” says Bright. “They have not shared a sequence that they collected from any infected animal in the last eight weeks.” And while the agency is sporadically submitting virus sequences to an international database, the data shared, Bright says, is largely from animals infected in March and early April…….
The federal, state, and local arms investigating and monitoring this strain of bird flu “have very collegial, collaborative, candid, discussions,” says Paul Friedrichs, the White House director of the Office of Pandemic Preparedness and Response Policy. “We don’t always agree, which is exactly what you expect from a complex situation, but what we always do is get to a decision and move out on it.”
For now, though, the researchers are consistent in their refrain about what’s needed: heightened surveillance and testing, testing, testing. “It is going to adapt,” Rick Bright says of H5N1. “We’ve watched it adapt over the years among bird species, and we know it’s what influenza viruses do.” The time to get ahead of that evolution, experts say, is now.
…….
:tiphat:
https://fortune.com/2024/06/11/pandemic-bird-flu-h5n1-spread-health/?abc123
