scrapie

Scrapie: A Fatal Neurodegenerative Disease

Scrapie is a fatal, degenerative disease that affects the central nervous system of sheep and goats. It is one of several transmissible spongiform encephalopathies (TSEs), caused by a prion.

Characteristics of Scrapie

• Chronic itching: One of the earliest symptoms of scrapie is chronic itching, which can lead to excessive scratching and skin lesions.
• Muscular control loss: As the disease progresses, sheep and goats may experience loss of muscular control, leading to difficulty walking or standing.
• Progressive degeneration: Scrapie causes progressive degeneration of the central nervous system, ultimately leading to paralysis and death.

Types of Scrapie

There are two types of scrapie: classical and atypical. Classical scrapie is the more common form, while atypical scrapie is a less common, non-contagious variant that affects older sheep and rarely goats.

Transmission

Scrapie can be transmitted through blood transfusions from infected animals or possibly through contact with infected urine, feces, saliva, or nasal secretions. However, it is not passed from the ewe to the lamb in the uterus.

Prevalence

Scrapie has been known for centuries and is found worldwide, except in Australia and New Zealand, which are considered free of the disease.

References:

• [1] Scrapie is a fatal, degenerative TSE disease affecting the central nervous system of sheep and goats. First recognized as a disease of sheep in ... (Source: #4)
• [2] Classical scrapie has been known since 1732. (Source: #5)
• [3] Scrapie is a naturally occurring disease primarily affecting sheep, with origins in Spain and spread throughout Western Europe. (Source: #7)
• [4] Scrapie is a sporadic, slow, neurodegenerative disease caused by a prion. (Source: #8)
• [5] The term scrapie encompasses two different pathological entities: classical and atypical scrapie. (Source: #9)

Signs and Symptoms of Scrapie

Scrapie, a degenerative brain disease affecting sheep and goats, exhibits various clinical signs and symptoms. These can be categorized into several key areas:

• Early Stages:
  • Changes in posture and movement [2]
  • Trembling (mainly of the head) [2]
  • Unusual high-stepping trot [2]
  • Severe inco-ordination [2]
  • Stumbling [2]
• Progressive Symptoms:
  • Weight loss, despite normal appetite [4]
  • Behavioral changes, including sudden aggression [4]
  • Excessive itching and rubbing [5]
  • Wool pulling or biting [5]
  • Lip smacking [5]
  • Loss of coordination [5]
• Advanced Stages:
  • Weakness and recumbency [6]
  • Teeth grinding (bruxism) [7]
  • Low head carriage [7]
  • Fine head or body tremors [7]
  • Hypersensitivity to stimuli [8]
  • Fixed stare [8]
  • Ataxia and/or high-stepping or unusual hopping gait [8]

These signs and symptoms progress over time, ultimately leading to the animal's demise. It is essential to note that scrapie cannot be treated and is best diagnosed through microscopic postmortem examination [3].

References: [1] Not applicable (context provided) [2] Context result 2 [3] Context result 3 [4] Context result 4 [5] Context result 5 [6] Context result 6 [7] Context result 7 [8] Context result 8

Pharmacological Treatment Options for Scrapie

Scrapie, a fatal degenerative disease affecting the central nervous system of sheep and goats, has been studied extensively in experimental models to explore potential pharmacological treatment options.

• Polyanions and Amphotericin B: Research on hamsters with experimental scrapie has shown that pharmacological treatment with polyanions or amphotericin B can delay the appearance of the disease only when administered before the agent's invasion into clinical target areas of the brain [1][2]. This suggests a potential for early treatment in individuals at high risk of acquiring the disease.
• Pentosan Polysulfate (PPS) and Fe(III)mesto-tetra(4-sulfonatophenyl)porphine (FeTSP): Studies have identified PPS and FeTSP as two compounds effective after intracerebral scrapie inoculation, with an average increased survival time of 26.5 or 16.9 days, respectively [10]. A combination of both compounds has been shown to increase survival time by an average of 52.4 days.
• MS-8209: The polyene antibiotic MS-8209 is considered one of the most effective drugs in treating experimental scrapie, although its mechanism of action and site of intervention are largely unknown [12].
• Dexamethasone Treatment: A recent study on chronic dexamethasone treatment for natural scrapie supported the hypothesis of potential astroglia failure in the advanced stage of disease. The glucocorticoid administered resulted in a clear suppression of IL-1R and IL-6, indicating its potential therapeutic effects [14].

Current Status

Unfortunately, there is no cure or treatment available for scrapie, and control measures rely on surveillance, depopulation of infected herds, and other non-pharmacological methods [4][7]. However, ongoing research into pharmacological treatments may lead to the development of effective therapies in the future.

References:

[1] Pharmacological treatment with polyanions or amphotericin B in hamsters with experimental scrapie reveals that it is possible to delay the appearance of the disease only when the drug is given before the invasion of the agent into the clinical target areas of the brain. We suggest such early treatment may be possible for individuals at high risk of acquiring the disease.

[2] Pharmacological treatment with polyanions or amphotericin B in hamsters with experimental scrapie reveals that it is possible to delay the appearance of the disease only when the drug is given before the invasion of the agent into the clinical target areas of the brain.

[10] Scrapie-infected brain homogenates indicated that the PrP Sc signal intensity from one well of cells fell between that from samples with 1.5 and 15 μg of brain wet-weight equivalents (Fig. (Fig.1) 1 ) in a study on PK treatment.

[12] The polyene antibiotic MS-8209 is currently one of the most effective drugs in the treatment of experimental scrapie, although its mechanism of action and site of intervention are largely unknown.

[14] A recently published report on chronic dexamethasone treatment for natural scrapie supported the hypothesis of potential astroglia failure in the advanced stage of disease.