This is creepy:

TWIN FALLS, Idaho (Reuters) - In late May Marjorie Skinner played golf well enough to place fourth in a Memorial Day weekend golf tournament. Yet within weeks, the previously vibrant retiree suddenly started losing her ability to speak.

By the time her family buried her on Friday, she was the fifth suspected victim in the same sparsely populated area of Idaho of Creutzfeldt-Jakob Disease (CJD), a rare brain-wasting disease that typically afflicts only one in a million people....

"Five (cases) in one valley is pretty serious," Sue Skinner, Marjorie's daughter in law, said in an interview. "It's a grave concern in our family."

..."Is what is happening in Idaho an anomaly, a statistical fluke? That is possible," said Ermias Belay, a top CJD expert with the Centers for Disease Control and Prevention in Atlanta who is helping advise officials in Idaho. "But once it exceeds 1.5 or 2 per million, you start asking questions."...

One in a million means that we should have had only about five cases in the whole of Idaho (population 1.3 million), not five in one valley.

Mad cow disease is variant CJD, and it's distinguishable from this spontaneous form of CJD, according to scientists. However, not everyone believes it's that simple; a 2004 New York Times article, on what may be a similar CJD cluster in New Jersey, notes that

John Collinge, the premier prion researcher in England ... [has] argued that experiments conducted in mice suggest that infections with mad cow can sometimes look like sporadic C.J.D. Collinge [has] recommended that ''serious consideration should be given'' to the idea that some of the more recent sporadic C.J.D. cases in Europe were in fact related to mad cow disease.

Oy...