Transmissible spongiform encephalopathies(TSEs), also known as prion diseases, are a group of degenerative, progressive, and fatal disorders that affect both humans and animals. These diseases severely damage brain tissue, giving it a spongy appearance due to the buildup of misfolded prion proteins, also referred to as proteinaceous infectious particles.

Unlike normal proteins, abnormal prions influence healthy and harmless proteins to misfold as well, triggering a chain reaction that leads to widespread neurological damage. As a result, individuals with TSEs experience cognitive decline, personality changes, psychiatric issues, lack of coordination, and unsteady walking. Additional symptoms include unintentional jerking movements, unusual sensory experiences, insomnia, seizures, and vision problems.

As the disease advances into its terminal stage, patients suffer extreme mental decline and gradually lose the ability to move or speak, eventually leading to a painful death within a few months or years.

Although TSEs cannot be spread through casual contact, they are particularly concerning due to their various transmission routes and the challenges involved in preventing an outbreak. As demonstrated during the bovine spongiform encephalopathy(BSE), or mad cow disease, epidemic in the United Kingdom, humans can contract prions through the consumption of contaminated meat products, resulting in variants of Creutzfeldt-Jakob disease(CJD).

Additionally, a rare instance of prion transmission can occur through contact with contaminated surgical instruments, tissue transplants, or blood products. Unlike viruses or bacteria, prions contain no DNA or RNA, which makes them highly resistant to standard sterilization techniques and allows them to survive procedures that would typically impair other pathogens. This resilience, combined with their ability to evade the immune system and spread silently within the victim‘s nervous system for months or years before symptoms appear, contributes to the difficulty of protecting at-risk populations.

Diagnosis of TSEs is particularly challenging because definitive confirmation often requires examination of brain tissue, which is typically performed post-mortem. Imaging techniques, such as MRI, and tests to detect abnormal prion proteins in cerebrospinal fluid-which is the clear liquid that surrounds and protects the brain and spinal cord, acting as a cushion, shock absorber, and transport system for nutrients and waste-are utilized by doctors to aid in diagnosis, but they cannot prevent disease progression. Some TSEs are inherited due to mutations in a gene called PRNP, which provides instructions for making normal prion proteins, causing these proteins to misfold and initiate the disease. Sporadic cases, on the other hand, arise without a known cause.

Currently, no effective treatments exist to stop or reverse neurodegeneration, and medical care is limited to managing symptoms and providing supportive relief. Because TSEs are fatal, difficult to detect, and currently incurable, ongoing research, public health measures, and monitoring of both humans and animals are essential to prevent future outbreaks and protect the well-being of society.

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