MAD COW DISEASE

During the last few years you have heard about "mad cow disease," which not only has wreaked havoc in the British economy but also brought fear into the hearts of the European people because man can be infected with it by eating contaminated meat.

This article is about the history of this disease and what causes it. You will see why it is important to make sure that cattle-raising people are not saving money by feeding the livestock with food from unknown and usually cheap sources.

First, it is important to know that mad cow disease belongs to a group of pathologies known as spongiform encephalopathies because the brain of the affected animals--or humans--becomes so full of holes that it resembles a sponge. In general, it takes years or decades for the symptoms to appear.

The most common form of the disease is scrapie, found in sheep and goats. Sick animals lose coordination and eventually they cannot stand. In some cases, they develop an intense itch that leads them to scrape off their wool or hair (hence the name "scrapie"). Other animal prion diseases are transmissible mink encephalopathy, chronic wasting disease of mule deer and elk, feline spongiform encephalopathy and bovine spongiform encephalopathy. The last one, mad cow disease, is the most worrisome and is abbreviated as BSE.

It was first identified in 1986 by G. A. H. Wells and J. W. Wilesmith of the Central Veterinary Laboratory in Weybridge, England .

In humans, Dr. Zigas from Australia and Carleton Gadjdusek from the USA first described a disease in the Fore aborigines from Papua New Guinea that started with loss of coordination (In medical terms, ataxia) and was followed by dementia and death. They called it "the laughing death" and the natives called it Kuru. Even though they did not know the cause of the disease they thought that it was probably due to the practice of the natives' honoring their dead by eating their brains. When such practices stopped Kuru disappeared.

Another similar human disorder is Creutzfeldt-Jakob disease, which is rare, striking one person in a million, typically around age 60. It can be inherited or it can be acquired iatrogenically. "Iatrogenic" means that it is caused by medical intervention, for example, by operating with instruments that have been used on sick patients and have not been properly sterilized.