Transmissible spongiform encephalopahties (TSEs) are an unusual group of diseases characterized by the presence of numerous small cavities in the brains of affected individuals. These cavisties are casued by the loss of neurons, and can take decades to form following the initial infection by the causative agent.

TSEs include scapie in sheep, bovine spongiform encepholopathy (BSE( or “mad cow” disease, chronic wasting disease in deer, and Creutzfeld-Jakob disease (CJD) in humans.

TSEs can be transmitted experimentally by ijecting infected brain tissue into a recipient animal’s brain. TSEs can also spead via tissue transplants and apparently by consumption of tainted food. In the late 20th century, the diease kuru was discovered among member of the Fore people of Papua New Guidea. These members engaged in ritualistic consumption of their dead which lead to the spread of a commonly fatal TSE through the tribes.

Mad cod disease spread widely among cattle herds of England in the 1990s becaseu cows were fed bone meal prepared form sheep and cattle carcasses to increase the protein content of their diet. Like the Fore, teh cattle were eating the tissues of animals that had died of the disease.

TSEs are casued by prions (proteinaceous infectious particles).