Creutzfeldt–Jakob disease (CJD) is a degenerative neurological disorder that is incurable and invariably fatal. It is a human form of mad-cow disease (bovine spongiform encephalopathy or BSE) even though classic CJD is not related to BSE. However, variant Creutzfeldt–Jakob disease (vCJD) is believed to be caused in humans by ingestion of beef infected with BSE (see also, Gerstmann–Sträussler–Scheinker syndrome). The disease is caused by abnormal misfolding and aggregation of the prion protein. This abnormally misfolded form of the protein is infectious not only among individuals, but also among species. Therefore, eating a misfolded bovine prion can cause the disease in humans. The first symptom of CJD is rapidly progressive dementia, leading to memory loss, personality changes, and hallucinations. Sporadic (non-inherited) CJD can be fatal within months or even weeks. Most victims die six months after initial symptoms appear, often of pneumonia due to impaired coughing reflexes. A similar disease caused by misfolded prion is Kuru, a disease in Papua New Guinea, which likely was transmitted through cannibalism before it was banned in the 1950s.