H5N1 Spread Still Uncertain

REDFIELD, Iowa (DTN) -- Even though it has been several months since the first case of HPAI in dairy cattle, the transmission source is still unknown as the spread continues across the country in both dairy and poultry operations.

In June, Iowa officials set up a mandatory surveillance zone for testing when a dairy farm has tested positive for highly pathogenic avian influenza (HPAI). See previous article here: https://www.dtnpf.com/…. Veterinarians haven't confirmed the transmission source for the H5N1 strain affecting both dairy cows and poultry, but several farms in these zones have tested positive for the H5N1 flu strain.

The Iowa zone radius is 20-kilometers for testing and has seen both positive and negative sites, which continues to baffle veterinarians on how the virus is spreading. Jeff Kaisand, Iowa's state veterinarian, said having this virus affect two different animals in the barnyard creates challenges for both those industries.

"The symptoms are different for dairy cows and poultry and the animals are treated differently if they have the virus," Kaisand added. "And with a zoonotic component with people contracting the virus in a few cases, then the CDC (Center for Disease Control) gets involved too."

Poultry have been diagnosed with HPAI in 48 states and 1,170 flocks, with over 100 million birds being euthanized. The virus has only been found in 175 head of livestock in 13 states as of Aug. 1. Only five human cases have been found in the U.S. since 2022.

VIRUS TRANSMISSION STILL UNSURE

Craig Rowles, a veterinarian and general manager of cage-free production for Versova Management Company based in Clive, Iowa, said he questions how one of their facilities in Sioux County, Iowa, broke with HPAI in a barn at the center of the operation with high biosecurity. "We don't understand how this virus spreads. We have very good biosecurity in our barns. The HPAI outbreak back in 2015 showed a lot of lateral transmission between poultry farms due to lack of biosecurity," he said. "This recent spread is not the same."

The Versova facility that broke with HPAI in May had to euthanize more than 4.2 million layer hens. Rowles said the northwest Iowa counties have been an area for several avian influenza cases in both poultry and dairy operations. The virus has been found in wild birds in all states which causes another challenge for both these industries. "We really don't know how this virus is transmitted, but we hope to find answers to that soon," he added.

Rowles, who has previously served as a pork veterinarian and raised pigs in the past, said the pork industry should be paying attention to how this virus is causing problems in other industries. He pointed out that many foreign animal diseases that cause issues in the pork industry could spread as quickly as HPAI has, and this virus could in fact be a problem at some point.

"The message for pork producers is that there haven't been any cases of this virus in pigs -- yet. Pigs are a great mixing vessel and there's a chance there could be avian influenza in pigs someday," Rowles said. "They need to know how to handle the personal protective gear for the employees in the operations and how animals will be treated."

Keeping contagious viruses and diseases out of the farm animal industries can help ensure and protect these operations. Kaisand said there are ways for livestock and poultry producers to help when a foreign animal disease is detected. These include registering for a premise identification number, having a biosecurity plan, reporting animals with clinical signs of a virus or disease, and having a biocontainment plan if their farm is infected and animals need to be euthanized.

Jennifer Carrico can be reached at jennifer.carrico@dtn.com

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