Bovine Spongiform Encephalopathy

Bovine Spongiform Encephalopathy (BSE), commonly known as mad cow disease, is a neurodegenerative disease that affects cattle. It is part of a group of diseases known as transmissible spongiform encephalopathies (TSEs), which are caused by prions, misfolded proteins that lead to brain damage. BSE has significant implications for animal health, food safety, and public health.

History

BSE was first identified in the United Kingdom in 1986. The disease rapidly spread among cattle populations due to the practice of feeding cattle with meat-and-bone meal that contained the remains of other cattle, including those infected with BSE. This practice was subsequently banned in many countries to prevent further spread of the disease.

Pathophysiology

BSE is caused by prions, which are infectious agents composed of protein in a misfolded form. Unlike bacteria or viruses, prions do not contain nucleic acids. The prion protein (PrP) is normally found in the brain, but in BSE, it becomes misfolded and accumulates, leading to brain damage and the characteristic "spongy" appearance of the brain tissue.

Transmission

BSE is primarily transmitted to cattle through the consumption of contaminated feed. There is no evidence of direct transmission between cattle or from cattle to humans through casual contact. However, humans can contract a variant form of Creutzfeldt-Jakob disease (vCJD) by consuming beef products contaminated with BSE prions.

Symptoms in Cattle

Cattle affected by BSE exhibit a range of neurological symptoms, including:

• Changes in temperament, such as nervousness or aggression
• Abnormal posture
• Lack of coordination and difficulty walking
• Decreased milk production
• Weight loss despite continued appetite

Diagnosis

Diagnosis of BSE in cattle is challenging and typically occurs post-mortem. The definitive diagnosis is made by examining brain tissue for the presence of prions using techniques such as immunohistochemistry or Western blotting.

Prevention and Control

Efforts to control BSE focus on preventing the entry of prions into the food chain. Key measures include:

• Banning the use of ruminant-derived protein in cattle feed
• Surveillance and testing of cattle for BSE
• Removal of specified risk materials (SRMs) from the food supply

Public Health Implications

The emergence of vCJD in humans, linked to BSE, raised significant public health concerns. vCJD is a rare and fatal condition that affects the brain, leading to psychiatric symptoms, neurological decline, and death. Measures to protect public health include strict controls on beef products and enhanced surveillance of human cases.

See Also

• Prion
• Creutzfeldt-Jakob disease
• Transmissible spongiform encephalopathy

References

• Prusiner, S. B. (1997). Prion diseases and the BSE crisis. Science, 278(5336), 245-251.
• Will, R. G., et al. (1996). A new variant of Creutzfeldt-Jakob disease in the UK. The Lancet, 347(9006), 921-925.

External Links

• World Health Organization: Bovine Spongiform Encephalopathy
• Centers for Disease Control and Prevention: BSE