Bird flu: Not just for the birds

Highly pathogenic avian influenza (HPAI), or “bird flu,” is on the move in dairy herds across the United States, and while scientists seemed baffled by the means of the H5N1 virus’ initial leap from poultry to a herd of Texas dairy cattle in March, poultry-industry insider William Wymore, of Owensville, believes its transmission can be easily explained.

The storage and land-application of poultry and meat-processing sludge is facilitating the spread of bird flu, he alleges.

Wymore, who broadcasts a podcast called “Good Morning, Sludge Truck,” is making it his business to educate the public about the hazards of stored and land-applied meat-processing residuals in Missouri and the nation as a whole.

“There has been virtually no pathogen-reduction on poultry-processing sludge before it leaves poultry-processing facilities,” Wymore said. “And, it’s known that meat-processing sludge contains pathogens, like E coli and viruses similar to the Avian flu.”

Wymore says sludge is composed of the residuals left after Dissolved Air Flotation (DAF) wastewater treatment separates the liquid portion from the solids. The liquid is pre-treated, then released into the environment. The sludge is then typically hauled away by waste-management companies for storage and land-application to farm- land in areas where it’s permitted.

“The sludge is a slurry of leftover chemicals from the DAF process, plus raw meat scraps, blood, feathers and whatever else might go down the drain in poultry plants,” Wymore said. “When the sludge is stored in open basins or containers, wild migratory birds like ducks and geese land in it, and when it’s land-applied, it’s a magnet for vultures and other predatory wild birds to pick through,” he said.

Wymore believes the land-application of meat-processing residuals holds the key to the transmission of the bird flu virus from poultry to cattle.

“Cattle graze on the pastures where the sludge has been land-applied and where vultures and geese have pooped,” Wymore said.

“[The] ingestion of feed contaminated with feces from wild birds infected with HPAI virus is presumed to be the most likely source of infection in the dairy farms,” a recent issue of Emerging Infectious Diseases, published by the U.S. Centers for Disease Control (CDC) stated.

Under certain conditions, Wymore said — according to a United States Geological Survey study published in The Scientist — the bird flu virus can be viable for up to 209 days.

“Two hundred and nine days is a lot longer than the amount of time the DNR recommends that cattle should be kept from grazing on pastures where sludge has been recently land-applied,” Wymore said.

An Environmental Assessment published by the Environmental Protection Agency confirms that meat-processing sludge can be a vector for the avian flu. Published in December 2023, the assessment details the environmental effects of pending new federal wastewater regulations for meat processing facilities.

It specifically lists the avian flu virus as a pathogen which can be present in the greater quantities of sludge which will be left for disposal after the new regulations are implemented.

In southwest Missouri, the prospective spread of bird flu from the land-application of meat-processing sludge is relevant.

Two companies, Synagro Central and HydroAg Environmental, currently have over 150 permits pending approval by the Missouri Department of Natural Resources (DNR) to land-apply meat-processing sludge and human biosolids to some 8,400 acres of Barry County farmland. A third company, Bub’s Inc., seeks to land-apply food-processing sludge in McDonald County.

Bird flu is outside of the DNR’s purview, said Heather Peters, Chief of the Water Pollution Control Branch of the DNR.

“We are required by law to make our permit decisions based on the state and federal laws and regulations,” she said. “[Bird flu is] regulated by the Department of Agriculture and/or the Department of Health. We don’t have specific criteria or inclusion in our regulations or underlying statutes for those diseases. As such, our ability or authority to limit them now in our regulations or permits may require some legal review.”

Peters did say that proposed rules can always be amended in the future, if additional statutory foundations are added.

“Avian flu and other animal diseases is a more difficult discussion,” Peters said. “But, one we are definitely willing to have.”

In addition to the possibility of land-applied poultry-processing sludge being a vector for bird flu, Wymore believes it can be the source of the virus itself, and can be present in sludge before it ever leaves poultry plants.

Wymore has been told that birds are checked for signs of avian flu before they enter the processing flow, but fears those checks aren’t extensive enough.

According to the Missouri Department of Agriculture (MDA), the flu virus is shed in the feces and respiratory secretions of infected birds.

“Virus in the feces indicates that it’s present in the digestive tract, but if lab tests (if they’re performed at all) are only conducted on respiratory samples, or vice versa, then there might be sick birds slipping into the processing flow,” Wymore said.

Sick, slaughtered birds mean avian-flu-laced sludge, Wymore said.

The MDA advises stringent biosecurity measures as a means of preventing the potential contamination of commercial poultry flocks on farms. However, Wymore wonders about the inconsistency of having biosecurity measures in place on the farm, while facilitating the spread of the virus at the end of the process.

“It’s ironic that the very birds they’re trying to protect from sickness on the front end, are being thrown out in raw pieces on open fields after they’re dead, so they can potentially contaminate the next live batch of birds — and now cattle and other mammals,” Wymore said.

According to a May article in the Springfield News-Leader, nine counties in Missouri have experienced new outbreaks in commercial poultry flocks since that time.

The total current U.S. poultry headcount of affected birds in 48 states is now well over 97 million, according to USDA figures.

As of July 3, H5N1 virus has been reported in 139 dairy herds across 12 states. In poultry flocks, the mortality rate for the HPAI virus can be 90-100%. Cattle usually exhibit mild symptoms, then recover.

On the Texas dairy farm where bird flu was first reported, 12 of 24 cats who drank raw milk produced by the sick cows died after exhibiting severe neurological anomalies. An autopsy performed on the cats at the University of Iowa revealed multiple brain lesions caused by the virus.

A few humans – four to date – have also been infected by the virus. All four people, located in states as disparate as Texas, Colorado and Michigan, worked with the sick dairy cattle. They experienced mild symptoms, then recovered.

In Missouri, avian flu has not been reported in humans or cattle, but the MDA is taking no chances. New protocols have been put in place for the Missouri State Fair in Sedalia, in August, requiring dairy cattle exhibitors to submit negative H5N1 milk sample test results prior to the fair, and to use their own milking equipment while at the fair.

While the CDC says the risk to humans from the bird flu currently remains low, they are closely monitoring the virus for signs of human-to-human transmission.

Wymore believes a simple test could limit the spread of the bird flu virus.

“Let’s test samples of sludge for the virus before it ever leaves meat-processing plants, before it’s stored in basins and land-applied to fields,” Wymore said.

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