"PRION DISEASES"

PRION DISEASES

group of rare, fatal neurodegenerative disorders caused by misfolded proteins in the brain. These diseases lead to severe brain damage and are transmissible, affecting both humans and animals

• Prions are infectious agents composed solely of protein, with no nucleic acids (DNA or RNA).

MAD COW - bovine spongiform encephalopathy (BSE), is a fatal neurological disorder in cattle caused by misfolded proteins known as prions.

Symptoms in Cattle:

• Changes in behavior, such as nervousness or aggression.
• Lack of coordination and difficulty walking.

Transmission to Humans:

• Humans can contract vCJD by consuming beef products contaminated with BSE prions.

Types of Prion Diseases

In Humans:

1. Creutzfeldt-Jakob Disease (CJD):

   • Most common human prion disease.
   • Can be sporadic (sCJD), hereditary (fCJD), or acquired (iCJD).
   • Symptoms include rapidly progressive dementia, ataxia, and myoclonus.

2. Kuru:

   • Historically found among the Fore people of Papua New Guinea, transmitted through cannibalistic practices.
   • Symptoms include tremors, loss of coordination, and eventually death.

3. Fatal Familial Insomnia (FFI):

   • A hereditary prion disease characterized by severe insomnia, autonomic dysfunction, and cognitive decline.

In Animals:

1. Scrapie:

   • Affects sheep and goats, characterized by itching, behavioral changes, and neurological symptoms.

2. Transmissible Mink Encephalopathy (TME):

   • Affects farmed mink and is similar to scrapie.

3. Chronic Wasting Disease (CWD):

   • Affects deer and elk, leading to weight loss, behavioral changes, and eventually death.

 

 

Transmission

• Sporadic Cases: Most cases of CJD occur sporadically without any known cause.
• Genetic Transmission: Some forms are inherited due to mutations in the PRNP gene.

Symptoms

Symptoms of prion diseases vary but generally include:

• Rapidly progressive dementia
• Memory loss
• Personality changes
• Ataxia (loss of coordination)
• Myoclonus (sudden muscle jerks)
• Visual disturbances
• Difficulty speaking and swallowing
• In later stages, patients may become unresponsive and bedridden.

 

 

Diagnosis

• MRI: Magnetic resonance imaging can show characteristic changes in the brain.
• Electroencephalogram (EEG): May show specific patterns associated with CJD.
• Brain Biopsy or Autopsy: Definitive diagnosis is often made post-mortem through histopathological examination.

Treatment

• No Cure: There is currently no cure for prion diseases, and treatment is primarily supportive.