How is Creutzfeldt-Jakob disease acquired?

Creutzfeldt-Jakob disease (CJD) is one of several related disorders collectively called prion diseases. These disorders affect man and animals and are now known to be caused by the abnormal configuration of a naturally occurring protein, PrP(c). By mechanisms still not well understood, this natural protein is converted into a pathologic variant, PrP(sc). The disease is 'acquired' spontaneously perhaps by posttranslational conversion of a PrP(c) into a PrP(sc) population. This sporadic form of CJD has been reported worldwide with a frequency of 1/million. Other modes of acquisition include the following: ingestion of brain tissue from deceased victims through ritual cannibalism at burial ceremonies formerly (and no longer) practiced by New Guinea Highlanders; iatrogenically, through corneal transplants from infected donors, inoculation of human growth hormone and gonadotropin prepared from infected human pituitary glands; from inadequately sterilized depth electrodes introduced neurosurgically into the brain during workups of patients with epilepsy, and applications of infected dura mater in neurosurgical procedures. Most recently, an infected bovine source (bovine spongiform encephalopathy) has been implicated and produces a new variant of CJD. Clusters of CJD in families in some populations have been recognized which are inherited in Mendelian fashion. These clusters are related to mutations of the PRNP gene in specific codons (e.g. codon 200). Homozygosity for these mutations increases the chances of manifesting the disease. Other potential methods of acquisition, such as by blood transfusion, surgical sutures, tonometers, consumption of hog brain or other organs and tissue, remain unproven.