Transmissible spongiform encephalopathy

Transmissible spongiform encephalopathy
Synonyms	N/A
Pronounce	N/A
Specialty	N/A
Symptoms	Dementia, ataxia, myoclonus
Complications	Death
Onset	Varies by type
Duration	Progressive
Types	N/A
Causes	Prions
Risks	Genetic predisposition, exposure to infected tissue
Diagnosis	Clinical evaluation, MRI, EEG, CSF analysis
Differential diagnosis	N/A
Prevention	N/A
Treatment	Supportive care
Medication	N/A
Prognosis	Poor
Frequency	N/A
Deaths	N/A

Transmissible spongiform encephalopathies (TSEs) are a group of progressive, invariably fatal, conditions that affect the brain and nervous system of many animals, including humans. They are caused by prions, which are misfolded proteins that induce other proteins to misfold, leading to brain damage and characteristic spongiform changes.

Types

TSEs include several distinct diseases, each affecting different species:

• Creutzfeldt-Jakob disease (CJD): Affects humans and is characterized by rapid neurodegeneration, leading to dementia and death.
• Bovine spongiform encephalopathy (BSE): Also known as "mad cow disease," affects cattle and can be transmitted to humans as variant CJD (vCJD).
• Scrapie: Affects sheep and goats, causing itching and neurological symptoms.
• Chronic wasting disease (CWD): Affects deer, elk, and moose, leading to weight loss and behavioral changes.
• Kuru: Historically affected the Fore people of Papua New Guinea, transmitted through ritualistic cannibalism.

Pathophysiology

TSEs are caused by prions, which are infectious agents composed entirely of protein. Unlike bacteria or viruses, prions contain no nucleic acids. The normal cellular prion protein (PrP_C) is converted into the disease-associated form (PrP_Sc), which accumulates in the brain and leads to the formation of amyloid plaques and spongiform changes.

Transmission

Transmission of TSEs can occur through several routes:

• Ingestion: Consuming infected tissue, particularly brain or spinal cord material, can lead to transmission, as seen in BSE and vCJD.
• Iatrogenic: Medical procedures involving contaminated instruments or tissues can spread the disease.
• Genetic: Some forms of TSEs, such as familial CJD, are inherited due to mutations in the prion protein gene.

Diagnosis

Diagnosis of TSEs is challenging and often involves a combination of clinical evaluation, magnetic resonance imaging (MRI), electroencephalography (EEG), and cerebrospinal fluid (CSF) analysis. Definitive diagnosis is usually made post-mortem through brain biopsy or autopsy.

Treatment

Currently, there is no cure for TSEs. Treatment is supportive and focuses on alleviating symptoms and improving quality of life. Research is ongoing to find potential therapeutic interventions.

Prognosis

The prognosis for individuals with TSEs is poor, with most patients succumbing to the disease within months to a few years after onset.

Prevention

Preventive measures include strict controls on animal feed, surveillance of livestock, and careful handling of medical instruments to prevent iatrogenic transmission.

Also see

• Prion
• Neurodegenerative disease
• Infectious disease
• Protein folding