Final answer:
Transmissible spongiform encephalopathies (TSEs) are fatal neurodegenerative diseases caused by prions, leading to brain damage and death. They are transmitted by eating contaminated tissue and can affect various species including humans and cattle. Diseases like kuru, BSE, and CJD are part of TSEs.
Step-by-step explanation:
Transmissible spongiform encephalopathies (TSEs) are a group of fatal neurodegenerative diseases caused by prions, which are acellular infectious agents. Prions induce abnormal folding of the prion protein (PrP), leading to brain damage and characteristic symptoms such as loss of motor control. Types of TSEs include kuru in humans, bovine spongiform encephalopathy (BSE), also known as mad cow disease, in cattle, and other variations affecting different species. Consuming meat, nervous tissue, or internal organs contaminated with prions can lead to transmission of these diseases within and between species.
The infectious form of PrP, known as PrPSC, converts the normal PrPC into the diseased form, leading to an aggregation of misfolded proteins which eventually result in the spongy lesions in the brain. These diseases are universally fatal and include Creutzfeldt-Jakob disease (CJD) in humans and scrapie in sheep. Due to the risk of transmission by blood, regions with BSE have faced blood donation bans to prevent spread to humans.