Creutzfeldt-Jakob disease (CJD) belongs to a family of diseases called "prion disease" [pree-ahn] caused by abnormal "prions", microscopic infectious agents made of proteins. Prions cause a number of diseases in a variety of mammals, including bovine spongiform encephalopathy (BSE or "mad cow disease") in cattle and scrapie in sheep.

It is important to rule out other diseases, which may be treatable, before confirming a CJD diagnosis.

Early symptoms tend to include personality changes and impaired muscular coordination, memory, judgment, thinking and vision.

While each type of CJD varies slightly, the rapid progression is a distinctive characteristic of the disease.

CJD is not contagious in the same way as a cold or flu. Normal social contact with someone with CJD should not put you at any greater risk of acquiring it.

While there is no proven treatment or cure for CJD yet, there are ways to help relieve symptoms and participate in research studies to help find treatments.