the New York Times published an article entitled “Five drug makers use material with possible mad-cow link.” This article followed a Public Health Service statement on Dec. 22, 2000 in Morbidity and Mortality Weekly Report (MMWR). MMWR is written by the Centers for Disease Control and Prevention (CDC).
The New York Times article and CDC report were prompted by the confluence of several events:
First, as of July 2000, about 175,000 cows in the United Kingdom developed a disease called “mad-cow” disease — a progressive disease of the nervous system of cattle.
Second, at least 80 people in the United Kingdom developed a progressive neurological disease called variant Creutzfeld-Jakob disease (vCJD) that may have resulted from eating meat prepared from cows with “mad-cow” disease.
Third, some vaccines are made with serum or gelatin obtained from cows in England or from countries at risk for “mad-cow” disease.
vCJD is caused by an unusual protein called a prion (proteinaceous infectious particle). Prions are found in the brains of cows with “mad-cow” disease and in the brains of humans with vCJD. Prions can also be found in the spinal cord and in the back of the eye (retina).
However, blood from infected animals or blood from infected people has never been shown to be a source of infection to humans.