Unless you live in the UK, it’s probable that your colleague has CJD, or Creutzfeldt-Jakob Disease. This is a very rare and always fatal brain disease, but probably has nothing to do with the consumption of beef. It’s been around for decades if not centuries. It’s only in the last decade that humans (in Europe) have gotten a variant form of CJD from eating beef from cows with the bovine form of the disease. There haven’t been any cases of that variant form of CJD transmitted by eating beef in the U.S.