The USDA announced on April 24 that the nation’s fourth case of Bovine Spongiform Encephalopathy (BSE), a brain wasting disease affecting cattle, was discovered in a 10-year-old cow. The USDA didn’t elaborate on the cow’s symptoms other than to say it was “humanely euthanized after it developed lameness and became recumbent.” Outward signs of the disease can include unsteadiness and lack of apparent coordination. Cows which “go lame” and can not stand are immediately euthanized and examined.
It had been euthanized at a Tulare County dairy farm a week earlier. The carcass was then sent to the Baker Commodities rendering plant near the town of Hanford, CA. The random testing (the US tests less than half a percent of all cows bound for market) took place that day.
Two farms have been quarantined by the U.S. Department of Agriculture as the agency continues to investigate last month’s discovery. Another investigation into a calf ranch where the infected cow was raised 10 years ago has also been launched, according to a statement from the USDA. USDA officials said the cow was never presented for human consumption and was not a threat. Other cattle raised with the infected cow have yet to be identified or located.
The dairy farm where the cow was initially discovered has been under quarantine since the discovery, agriculture officials said. Wednesday’s announcement of a second quarantine involves a farm closely tied to the initial discovery, the USDA said. Quarantine is standard procedure when a positive test result occurs. The agency is still trying to determine if any at-risk cattle are present at either of the two farms, although they declined to name the dairies in question or what state they were located in.
USDA officials also said on Wednesday that within the last two years, the diseased cow gave birth to a stillborn calf. They did not elaborate on how that carcass was disposed.
Cows contract the disease by eating rendered remains from other sick cattle, which are processed into protein supplements. In the United States it’s no longer legal to feed cattle to cattle. Rendered cattle remains are, however, used in chicken feed. In turn, the chicken droppings and spilled feed are then rendered back into cattle feed. Little documentation exists studying the safety of such practices.
U.S. health officials say there is no risk to the food supply. The California cow was never destined for the meat market, and it developed “atypical” BSE from a random mutation, something that scientists find happens occasionally. A natural protein in the body folds abnormally, forming a prion. This mis-fold continues and propagates further prions, eventually killing the brains cells. Cattle that are “downers”, cattle which can’t stand by themselves, are not allowed for human consumption. Generally they are sold to pet food manufacturers, where no such restriction applies.
The FDA and the California Department of Food and Agriculture have been examining feed records for the affected dairy. Ten separate suppliers have been identified. The USDA tests 40,000 of the approximately 35 million cattle slaughtered annually for BSE. Other countries, including Europe, blanket test all animals over a certain age, generally 24 months. Baker Commodities is a voluntary participant in the testing program.
Eating contaminated meat or some other animal products from cattle that have been infected with BSE is thought to be the cause of Creutzfeldt-Jakob disease. The fatal brain disease was blamed for the deaths of 150 people in Britain during an outbreak in the 1980s and 90s.