Dairy cattle moving between states must be tested for bird flu, Colorado Agricultural Commission rules

New protections have been put in place to prevent the spread of bird flu. The U.S. Department of Agriculture has confirmed Highly Pathogenic Avian Influenza -- or HPAI -- in dairy cattle in 34 dairy herds across nine states, including Colorado.

The Colorado Agricultural Commission held a meeting Tuesday to discuss an emergency rule to protect Colorado's poultry and livestock industries and residents by limiting the opportunity for the spread of HPAI.

The commission voted to approve the rule, which requires the testing of lactating dairy cattle moving between states. Prior to interstate movement, lactating dairy cattle are to receive a negative test for the virus.

Any positive result must be reported to the state veterinarian's office.

"At this point in time, it seems that the virus has a predilection for dairy cattle, specifically a predilection for mammary tissue and milk. We don't know why yet. We don't quite understand the mechanism of transmission," explained Dr. Maggie Baldwin, state veterinarian at the Colorado Department of Agriculture.

The USDA will begin sampling beef in states where cows tested positive. The USDA is also doing additional testing to see if there's any disease present in any of the state's other livestock commodities.

The FDA says commercial milk is safe to drink.

Dr. Jenna Guthmiller, assistant professor of immunology and microbiology at CU Anschutz Medical Campus, studies influenza viruses.

She also grew up on a dairy farm.  

"A very unique feature about these infections is that they actually are infecting the udders, so the part of the cow where the milk comes from," said Guthmiller. "One hypothesis for this transmission is the machinery used to milk the cow. This goes on the udders themselves and that is essentially taken from one cow to the next cow."

The CDC is working to monitor for infections in people commonly exposed to animals where the virus has been detected.  

"The odds of this becoming a pandemic leading to human-to-human spread does not seem to be a concern at the moment," said Guthmiller. "But that said, the more animals that get infected, and the more contact that people have with those animals that are getting infected, the odds that it can jump into humans and adapt to us and lead to human-to-human spread. That is really where the concern lies."

The Colorado Agricultural Commission says a town hall will be held in the near future for questions from the public.