Final answer:
Prion diseases, such as kuru and BSE, are spread in the food chain through the consumption of infected meat and tissues. This has led to significant health consequences for humans and animals.
Step-by-step explanation:
Prion diseases, such as kuru in humans and bovine spongiform encephalopathy (BSE) in cattle, are transmitted through the consumption of meat, nervous tissue, or internal organs from infected individuals of the same species. For example, kuru was spread among humans in Papua New Guinea through ritualistic cannibalism, while BSE was transmitted among cattle by including nervous tissue in their feed. This spread of prion diseases in the food chain has led to serious health consequences for both humans and animals, including loss of motor control and behavioral abnormalities.