APHIS Now Thinks Wild Birds Are to Blame for Highly Pathogenic Avian Influenza's Arrival on Four U.S. Dairies

The livestock industry continues to grapple with the first confirmed cases of Highly Pathogenic Avian Influenza (HPAI), more commonly known as bird flu, in cattle. On Monday, USDA's Animal and Plant Health Inspection Service (APHIS) confirmed a strain of HPAI was detected on four dairy farms, stating it believes wild migratory birds are to blame.

APHIS says additional testing was done on Friday, March 22, as well as over the weekend, after farms reported finding dead wild birds. Then, on Monday, March 25, APHIS said clinical samples of milk from sick cattle confirmed it was a strain of avian influenza.

“Based on findings from Texas, the detections appear to have been introduced by wild birds. Initial testing by the National Veterinary Services Laboratories has not found changes to the virus that would make it more transmissible to humans,” said APHIS in a release.

APHIS says animal health experts are working to better understand the situation, as well as the characteristics of the HPAI strain. Federal and state agencies are continuing to do additional tests for HPAI, including viral genome sequencing.

“The DNA testing they're doing on that virus is making it consistent with the wild bird flu that's in wild bird populations, but there is additional work being done,” Justin Smith, the Kansas Animal Health Commissioner told AgriTalk’s Chip Flory this week. “Right now, it looks like it's a wild bird incursion on our dairies, whether it be from the blackbirds or other birds.”

Related News: BREAKING: Mystery Illness Impacting Texas, Kansas Dairy Cattle is Confirmed as Highly Pathogenic Avian Influenza Strain

Federal and state agencies continue to assure consumers there is no concern about the safety of the U.S. milk supply, as the pasteurization process destroys any bacteria.

Avian influenza might be new to the dairy industry, but it’s taken a toll on the poultry industry. More than 80 million birds have been depopulated in the U.S. to control the disease in commercial poultry flocks. 

“In cattle, mortality appears to be zero. We don't have any reports of cattle directly dying from this disease,” says Dr. Fred Gingrich, cattle veterinarian and executive director of the American Association of Bovine Practitioners (AABP). 

“They're doing some genetic work on the virus itself. Mammalian markers show the given opportunity to pass from mammal to mammal, and they're not finding any of those markers in this virus at this point in time,” Smith told Flory.

HPAI in Minnesota Goat 

This is the first known case in cattle, but the first confirmed case in livestock occurred earlier this month in a young goat located in Minnesota. It's reported the goat lived on a farm in Stevens County in the same area where a poultry flock tested positive for the illness late last month. The goat shared the same pasture and water source as the poultry flock.  The case is still under investigation, but experts at University of Minnesota Extension are recommending producers check their biosecurity practices and not allow poultry, waterfowl and wildlife to share water sources or feed.

Symptoms and Signs of HPAI

According to the Texas Animal Health Commission, here’s a summary of what the industry knows right now:

• The symptoms of the illness last between 10 and 14 days.
• The exact cause of the illness is undiagnosed and still unknown.
• Clinical signs include a sudden drop in milk production.
• Some severely impacted cows are producing thicker, more concentrated, colostrum-like milk.
• The problem causes a drop in feed consumption with a simultaneous drop in rumen function, accompanied by loose feces and some fever.
• Impacted herds have reported older cows in mid-lactation may be more likely to be severely impacted than younger cows, fresh cows or heifers.
• Dry cows and heifers do not appear to be affected.
• Some herds have reported pneumonia and mastitis.

Gingrich says the main issue in impacted cattle is that they go off feed and milk production plummets.

“It appears the disease peaks in about three to four days and lasts 10 to 14 days. Older dairy cattle appear to be more clinically affected, with a more severely affected lactation,” Gingrich says. “Although it's not consistent with every herd, it appears it's mostly affecting animals in mid- to late lactation. It's pretty unusual that we have something going on in older animals but not in fresh cows."

Related News: Get the Facts Straight on Highly Pathogenic Avian Influenza

Gingrich says AABP understood there was a dire need to find answers for dairy producers. 

“We understand right now that the primary impact of this disease is economic. These herds lose about 20% of their milk production for 14 to 21 days, which is a huge economic loss," Gingrich says. “I think we always like to look for the bright side in a situation, and we don't appear to have mortalities associated with this disease. That's not happening, which is really great.”

What Dairy Producers Need to Know About HPAI

As more testing is done, and the industry tries to nail down the scope of the infections, Gingrich says his advice to dairy producers is simple: Be on the lookout for symptoms in your heard, and if you see an issue, immediately report it.

“Don't hide it, we all need to work together to continue the investigation,” Gingrich says. “If you have a sudden drop in appetite and milk production in your herd, the first person you should call is your veterinarian to get a diagnosis, whatever that might be. Secondly, we want dairy farmers to know the veterinary community cares about you. We certainly understand this is a scary time. So, make sure you're relying on your veterinarian and USDA and organizations such AABP for reliable information.”

The Kansas Animal Health Commission says the cases came on subtly, and dairies have already worked to step up biosecurity efforts to contain any potential outbreak.

Gingrich says his advice to veterinarians is to be aggressive with diagnostics.

“Even though we have these four positive samples, the investigation is ongoing,” Gingrich adds. “So, make sure you are working with your diagnostic labs and your state animal health officials to collect the appropriate diagnostics posted on our website. If you're an AABP member, we have a reporting portal where you can identify the herds with this syndrome.”