The fourth case in U.S. history of bovine spongiform encephalopathy, better known as mad cow disease, was discovered Tuesday in a dairy cow in California’s Central Valley, setting off a health scare and prompting reassurances from food experts.
The infected animal was discovered in random testing by the U.S. Department of Agriculture, which randomly tests some 40,000 cows a year for the disease. Mad cow disease first received worldwide attention during an epidemic in Britain in the 1980s and '90s in which more than 150 people and 180,000 cattle died.
The outbreak led to a ten-year ban on exports of British beef and prompted the USDA to change the U.S. rules for cattle food in 1997 so that “rendered” cows, animals that are processed for things like tallow and animal feed, could not be used as feed for other cows.
Humans can contract mad cow disease by eating meat from infected cows, but not by ingesting their milk. In this most recent California case, the infected animal "was never presented for slaughter for human consumption, so at no time presented a risk to the food supply or human health,” according to the USDA’s chief veterinarian, John Clifford, in a statement. Mad cow disease is on the decline due to changes in food safeguards; there were only 29 cases worldwide in 2011, down from a peak of 37,311 in 1992.
Is there reason to be concerned about this most recent example of mad cow disease? What can agricultural experts and farmers do to protect our food sources?
Michael Hansen, PhD, senior scientist at Consumers Union, the advocacy arm of Consumer Reports
Dr. Tom Talbot is a cattle producer and a veterinarian from Bishop, California; he also serves as the Chairman of National Cattlemen's Beef Association’s Cattle Health and Well-being Committee