Reference

Creutzfeldt–Jakob Disease (CJD) exists in several forms, each with its own characteristics and modes of transmission. The main types of CJD include:

1. Sporadic CJD (sCJD):

   • Prevalence: This is the most common form, accounting for about 85% of cases.
   • Cause: It occurs for unknown reasons, with no identifiable origin.
   • Age of Onset: Usually affects people around 60 years old.
   • Symptoms: Rapidly progressive dementia, along with myoclonus (muscle jerks).

2. Familial or Inherited CJD (fCJD):

   • Prevalence: Constitutes about 10-15% of CJD cases.
   • Cause: Caused by inherited mutations in the PRNP gene, which codes for the prion protein.
   • Symptoms: Similar to sporadic CJD, but patients may have a family history of the disease.
   • Age of Onset: Often seen in younger individuals compared to sporadic CJD.

3. Iatrogenic CJD (iCJD):

   • Prevalence: Extremely rare, less than 1% of cases.
   • Cause: Results from exposure to infected nervous system tissue during medical procedures, such as contaminated surgical instruments or human growth hormone.
   • Symptoms: Similar to sporadic CJD, including rapidly progressive dementia and motor symptoms.

4. Variant CJD (vCJD):

   • Prevalence: Very rare, but has gained public attention due to links to Bovine Spongiform Encephalopathy (BSE), commonly known as "mad cow disease".
   • Cause: Acquired through consumption of beef infected with BSE.
   • Symptoms: Unlike other forms, vCJD affects younger individuals (average age of onset in late 20s) and features more psychiatric symptoms initially, such as depression and anxiety, followed by neurological dysfunction.

5. Acquired CJD (including vCJD and iCJD):

   • This includes any form of CJD acquired through external means, such as ingestion of prion-infected food (vCJD) or medical contamination (iCJD).

For more detailed information, you can refer to these resources:

• NHS on CJD
• Mount Sinai Health Library
• Mayo Clinic

Here is an image summarizing the different forms of CJD: