May 22, 2023 at 11:49 a.m.
Virulent strain of avian flu leads to death for millions of birds
Wisconsin, Minnesota hit hard by lethal virus
While the disease, Highly Pathogenic Avian Influenza (HPAI), poses a threat to humans only on rare occasions, it has decimated the nation's poultry and backyard bird flocks, causing a spike in egg prices, and it is killing wild birds in historic numbers.
It's impossible to know just how many birds have been killed, but, according to the U.S. Department of Agriculture, nearly 59 million birds in commercial poultry and backyard flocks have died - either from infection or by culling all birds on those premises where at least one confirmed infected bird was found.
At the other end of the spectrum, as of May 7, there had been 6,737 HPAI detections in wild birds in the U.S., indicating the number of confirmed positive wild bird samples through the National Wildlife Disease Program. However, scientists say the 6,737 known wild bird fatalities represent an exponential undercount because most birds become sick and die in the wild and are never seen by people.
In the latest numbers, Minnesota leads the way with 566 confirmed wild bird fatalities in birds carrying the H5N1 strain; Wisconsin recorded 214; Michigan, 213; Iowa, 205. No one knows why the Minnesota number is so high - it could represent a more infected population, driven by Minnesota's prominence as a wild bird thruway of sorts, or it simply could mean more birds were submitted for testing, experts have said.
One thing is for certain, though. The avian flu outbreak is one of the worst wildlife epidemics in recorded history. In Wisconsin last year, 29 domestic flocks in 18 counties were confirmed with HPAI, while the nationwide fatalities related to HPAI represented the largest animal disease outbreak ever, surpassing the 2014-15 bird flu outbreak.
There are multiple reasons scientists are concerned. For one thing, the contagion in wild birds threatens farmed bird flocks if security measures are breached (and they have been). For another, the flu threatens already endangered bird populations: Wildlife officials have already confirmed the deaths of three California condors found in northern Arizona due to HPAI.
And researchers at Cummings School of Veterinary medicine at Tufts University, led by virologist and senior scientist Wendy Puryear and post-doctoral researcher Kaitlin Sawatzki, concluded that an outbreak of HPAI was associated with the deaths of more than 330 New England harbor and gray seals along the North Atlantic coast in June and July 2022.
Then, too, infections in humans are rare but not out of the question. In late April, the CDC reported that one person in Colorado tested positive for avian influenza; that person was directly exposed while engaged in depopulating poultry with presumptive H5N1 bird flu. The patient suffered fatigue for a few days but was otherwise OK.
The strain has been circulating and on the hunt for host birds since 2020, but, this April, Tom Vilsack, the secretary of the U.S. Department of Agriculture, said there were hopeful signs that the corner was being turned on the outbreak.
The USDA is emphasizing biosecurity measures - such as the removal of standing water, keeping carcasses and compost piles covered at all times, and reducing food sources, among other things - as the best defense against HPAI.
According to Vilsack and USDA under secretary Jenny Moffitt, as of April, improved biosecurity measures by the commercial industry had vastly reduced the number of detections in the commercial sector. In March 2022, for example, there were a total of 51 commercial poultry HPAI detections, while in March 2023 there were only seven commercial poultry detections, a decrease of 85 percent year-over-year.
"All of these lessons learned have informed our current strategy of stamping out and eradicating HPAI - which continues to be the most effective strategy because it works," Moffitt said. "For example, during the 2014-2015 outbreak, 70 percent of HPAI cases were attributed to lateral spread. Whereas in this outbreak, lateral spread has been reduced to 15 percent. But we need to remain vigilant, especially as wild birds continue to pose disease risks. We all must recognize the important role biosecurity plays in limiting the impact of wild birds at farms and facilities."
In March, the Wisconsin Department of Agriculture, Trade and Consumer Protection (DATCP) cautioned poultry owners of the ongoing threat of HPAI, especially during the spring migratory period for wild birds.
This one is different
One of the alarming aspects of this virus is that it has spread in wild bird flocks as well in farmed birds, and a second concern is that it is less seasonal.
In an April study released by the University of Maryland, "Why this bird flu is different: Scientists say new avian influenza requires urgent coordinated response," researchers tracked the arrival and spread of H5N1, and concluded that its deadly impact on wild birds and a shift from seasonal to year-round infection signaled dangerous changes in avian influenza in the U.S.
"We've been dealing with low pathogenic avian influenza for decades in the poultry industry, but this is different," said Jennifer Mullinax, assistant professor in the University of Maryland Department of Environmental Science & Technology and a co-author of the study. "Low pathogenic disease is less contagious and easier to contain than the highly pathogenic variety."
In an interview at the University of Maryland, Mullinax said the HPAI was "wiping out everything in numbers that we've never seen before."
"This paper illustrates how unprecedented it is, and describes what we think is coming," Mullinax said. "It's really a call to arms saying, we can't afford to address this from our individual silos. Federal agencies, state agencies, the agriculture sector and wildlife management, we are all going to have to deal with this together, because we can't afford not to."
Johanna Harvey, a postdoctoral researcher at the University of Maryland and lead author of the study, said that, unlike H5N8, this disease is heavily impacting wild birds.
"It's difficult to estimate how many birds are truly affected across wild populations, but we're seeing dramatic disease impacts in raptors, sea birds and colonial nesting birds," Harvey said. "And we now have the highest amount of poultry loss to avian influenza, so this is a worst-case scenario."
The data also showed a transition from a seasonal to year-round disease. Previous outbreaks of avian influenza - whether low pathogenic virus that is endemic in the U.S. or highly pathogenic H5N8 in 2015 - typically occurred in the fall, the researchers wrote, which meant farmers could prepare for seasonal outbreaks, cull flocks to halt the spread of disease, and have nearly a full year to recover losses.
But the new virus appears sustained throughout the year, with summertime disease detections in wild birds and poultry outbreaks occurring in both the spring and fall.
In the paper, the research team recommended a management approach based on a method called Structured Decision-Making, which follows a specific process of identifying and bringing together relevant individuals with an interest, expertise or stake in an issue, distinguishing the unknown from the known factors, and establishing measurable goals and actions with quantifiable results.
The process is much like dealing with a human pandemic, Mullinax wrote.
"Good decision science is what you do when you don't know what is going to happen next," Mullinax said in a University of Maryland interview. "This is a novel virus for North American birds, so no one knows if their immune systems will adapt, or how long that will take, or what that will look like. Where do we direct our funds for maximum benefit? Is it a vaccine? How do we track it in wild birds? Do we test the water or the soil? What are the triggers for different actions, and how do we measure if we're succeeding? These decisions have to be made on multiple scales."
Possible vaccine
Both lawmakers and researchers are warming to the idea of a vaccine, but that step could be a few years away, given the need to adequately test any vaccine.
According to the USDA, its Agricultural Research Service (ARS) began avian influenza vaccination trials in April and its researchers are testing several vaccine candidates.
"Initial data from the animal study with a single dose of the vaccine are expected to be available in May 2023," the USDA states. "The researchers expect to have two-dose vaccine challenge studies with results in June 2023."
Should those trials be successful, and should USDA elect to continue development, the next step would be to identify manufacturers interested in vaccine production, and, after that, the USDA says there are 20 discrete stages to complete before vaccine delivery.
"These stages begin with feasibility work by the manufacturer and culminates with product label submission and review," the agency states. "General timeframes are 2.5-3 years; however, in emergency situations manufacturers may expedite development, resulting in a shortened timeframe to licensure."
From vaccine development to production timelines, to dissemination to flocks, there are many factors that make implementing a vaccine strategy a challenge and it would take time to deliver an effective vaccine, the USDA stated.
"In a best case scenario, USDA estimates an 18-24 month timeline before having a vaccine that matches the currently circulating virus strain, is available in commercial quantities, and can be easily administered to commercial poultry," the agency stated.
According to the USDA, wild birds can be infected with HPAI and show no signs of illness. They can carry the disease to new areas when migrating, potentially exposing domestic poultry to the virus. APHIS' wild bird surveillance program provides an early warning system for the introduction and distribution of avian influenza viruses of concern in the United States, allowing APHIS and the poultry industry to take timely and rapid action to reduce the risk of spread to the poultry industry and other populations of concern.
Among the domestic poultry affected are chickens, turkeys, pheasants, quail, ducks and geese - in both big commercial operations and increasingly popular backyard flocks. It can be spread by contact with infected birds or the premise where the birds are housed, equipment used on the premise with infected birds, and clothing worn by people working with poultry, the USDA states.
In May of 2022, the DNR confirmed that wild red fox kits in Wisconsin tested positive for a strain of HPAI. Additional cases have also been confirmed in other wild mammals including bobcats, skunks, bears, and seals.
HPAI can spread from birds to people and cause serious illness and even death. People who have gotten sick with HPAI have been in direct contact with infected birds or their premise.
In Wisconsin, the latest confirmed wild bird infected with HPAI was a bald eagle found in Sheboygan. Most of the confirmed samples have been found in Burnett and Door counties, though one was found in Forest County in October 2022, and two were found in Lincoln County in April of 2022.
Richard Moore is the author of "Dark State" and may be reached at richardd3d.substack.com.
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