Creutzfeldt-Jakob Disease (CJD) is a brain disorder characterized by memory loss, jerky movements, gait disorder, rigid posture, and seizures due to a rapid loss of cerebral cells caused by transmissible proteins called prions. The disease is correctly diagnosed in anywhere from one to two people per million and it usually appears in mid-life with an average disease onset age of 50.
The prion that is believed to cause Creutzfeldt-Jakob exhibits an amino acid sequence and configuration which makes it insoluble in water, while the normal protein is highly soluble. So, as the numbers of defective prion proteins propagate and increase exponentiallyly, the process leads to a huge load of insoluble prions in affected cells. This load of proteins disrupts cell function and causes cell death. Once the prion is transmitted, the defective proteins invade the brain like a forest fire and the patient dies within a few months time (a few patients live for about 1-2 years). The defective protein can be transmitted by human growth hormone products, corneal grafts or dural grafts (acquired form) or it can be inherited (hereditary form) or appear for the first time in the patient (sporadic form). In the latter two forms the defective protein is not transmitted from an external source but already exists in the genes of the individual.
Diagnosis is usually established by clinical findings and certain characteristic atypical electroencephalography findings. Biopsy of living brain tissue is definitive. There is currently no treatment for the disease, though as of December 2002 the first test of a proposed treatment (injection of pentosan polysulphate directly into the brain) has been approved in Britain.
A new variant of the disease (usually called just variant Creutzfeldt-Jakob Disease (vCJD) but sometimes new variant Creutzfeldt-Jakob Disease (nvCJD)) is distinguished from the classical type by its early onset (usually in the 20s) and a predominance of psychiatric and sensory symptoms. The prions in this form are thought to be transmitted by consuming the meat of bovines with so-called mad cow disease (Bovine Spongiform Encephalopathy), although there is no definite proof of this association as yet. However over 95% of identified cases of vCJD are in Britain, which suffered a mad cow disease epidemic in the mid-80s.
On September 26, 2003, it was reported that an experimental treatment given to a Northern Irish teenager halted the progress of brain damage caused by variant Creutzfeldt-Jakob disease. The drug, called pentosan polysulphate and commonly used to treat cystitis, was injected into the patient's brain. The patient weight and heart rate returned to normal levels after receiving the treatment. Still, there is no cure for vCJD, a fatal disease. 
The two German neurologists who first described this disease are Hans Gerhard Creutzfeldt and Alfons Maria Jakob. Interestingly, most of the clinical findings described in their first papers do not match current criteria for Creutzfeldt-Jakob disease, and it is considered highly likely that the patients in their initial studies were suffering from a completely different disorder.
The United States Centers for Disease Control and Prevention reports the following: