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Bovine spongiform encephalitis is a transmissible disease that causes degeneration of the nervous system in cattle. Although it has a long incubation period that can last as long as eight years, once the symptoms appear the animal will die within just a few short weeks or months. Since it causes damage to the brain and spinal cord, the symptoms can vary from changes in behavior to loss of coordination. Bovine spongiform encephalitis, also known as mad cow disease, is always fatal. There is no treatment.
A cow with bovine spongiform encephalitis may have trouble standing and walking. It may exhibit both changes in behavior and a gradual decrease in coordination. Although it may have a healthy appetite, the animal may lose weight and its milk production may decrease. It will continue to deteriorate until it either dies or is destroyed. Millions of cows have been destroyed in an attempt to prevent bovine spongiform encephalitis from spreading.
The disease was first discovered in November of 1986 when a new form of neurological disease was recognized in cattle on livestock lots in the United Kingdom. Studies showed that the cattle had been infected after ingesting feed that had been processed using parts from an infected cow. It was later determined that many people ate beef from diseased animals that had been slaughtered before any symptoms of bovine spongiform encephalitis had manifested.
Early in December of 2003, an event took place in the United States that was to have global repercussions. The US Department of Agriculture (USDA) assumed that a nonambulatory cow called a “downer” was disabled due to complications from giving birth and not from disease, and determined that its meat was safe. After the downer was slaughtered, its meat was sent off to be rendered into feed. Samples taken from the downer cow subsequently tested positive for bovine spongiform encephalitis, and 53 countries immediately banned the importation of US beef and beef products. Shortly afterward, the USDA banned downer cows from being rendered into animal feed, and also banned many bovine products from entering the human food chain.
Bovine spongiform encephalitis is transmissible to humans who can contract it by eating a meat product from an infected cow. In humans the disease is called Creutzfeldt-Jakob disease. Eating the meat from an infected animal isn’t the only cause of Creutzfeldt-Jakob disease, and the symptoms are identical to those of bovine spongiform encephalitis.