The discovery of bovine spongiform encephalopathy, or BSE, in an 10-year-old dairy cow has raised questions across the U.S.
The fourth case of BSE in the U.S. was found in a 10-year-7-month old dairy cow from a dairy farm in Tulane County in California’s Central Valley, said U.S. Department of Agriculture chief veterinary officer John Clifford. Clifford confirmed the case on April 24.
According to Marty Zaluski, Montana State Veterinarian, the cow was presented to a facility that transports animals for rendering.
Rendering plants do not produce food for human consumption; rather they render animal carcasses into byproducts such as adhesives, grease, and more.
“She was spot sampled and it came up positive,” said Zaluski. “Interestingly, this animal came up with atypical BSE. While they don’t quite know the exact origin of this atypical type, we don’t think it is the kind spread through ruminant proteins like happened in England in the 1990s.”
BSE is not a contagious disease, Zaluski said. That means it is not spread from animal to animal through contract.
The primary means by which animals become infected is through consumption of contaminated feed, he said.
Yet, because this case is atypical, there is no evidence that it was contracted through feed infected with a BSE agent.
“It very well could be a spontaneous BSE mutation that happens through a random event,” explained Zaluski. In infected cattle, the symptoms typically appear when the animals are 30 months to 8 years of age.
Once symptoms begin to appear, the animal’s condition deteriorates rapidly, often as quickly as two weeks. According to the USDA, BSE causes degeneration of the nervous system.
Affected animals might display changes in temperament, such as nervousness or aggression, abnormal posture, loss of coordination, difficulty in rising, decreased milk production, or loss of body weight despite continued appetite, the USDA says.
Because of that long incubation period, the USDA has quarantined herds that have had contact with the infected cow. They have also traced her offspring and conducted tests but Zaluski said off-spring tested so far have tested negative for BSE.
“We don’t think this case is an indicator of a greater problem,” said Zaluski. “We actually have a surveillance system in place that goes well above and beyond the standards set by the international community.”
He said the international community is also viewing the case
with a “degree of logic.”
“They are not being overly reactionary so I don’t foresee a dramatic outcome - certainly nothing to compare to the diagnosis of BSE in December of 2003,” said Zaluski. “What I would tell folks is to stay vigilant, but not to get too amped up.”
To learn more about atypical BSE, Zaluski recommended producers check out the Internet at the following site: http://blogs.nature.com/news/2012/04/california-bse-prion-comes-with-a-different-twist.html.
The USDA is also covering the issue at: http://blogs.usda.gov/2012/04/25/usdas_chief_veterinary_officer_on_the_recent_bse_case/.