Mad cows and sick monkeys.

The emergence of 10 unusual cases of Creutzfeldt-Jakob disease (CJD) in the United Kingdom in April alarmed Europe and electrified the world's scientific community. It appeared that all 10 patients had contracted what scientists believe is a newly recognized human variant of "mad cow" disease (SN: 4/13/96, p. 228).

Now, two French scientists report in the June 27 Nature the first direct evidence of a link between mad cow disease and CJD. They have found provocative similarities between brain lesions in monkeys injected with brain tissue from affected cows and those in humans with the new form of CJD. The findings suggest that mad cow disease can be transmitted to humans; however, the researchers stress that their work, though suggestive, does not provide proof of the link.

The study began in 1991, when Corinne Lasmeszas and Jean-Phillipe Deslys of the French Atomic Energy Commission and that nation's Army Health Service injected crushed brain tissue from diseased cows into the brains of one newborn and two adult rhesus monkeys.

Three years later, all three monkeys developed the classic symptoms of the human version of mad cow disease, including anxiety and depression. After the monkeys died, necropsies revealed that all three had identical types of brain lesions. A comparison with the lesions found in the 10 recently described British victims showed that the brain abnormalities were "strikingly" similar, suggesting that the mad cow agent causes disease in humans.