Scrapie-susceptible sheep are typically infected in which manner?

• A. As lambs through contact with infected placenta and birth fluids, not necessarily mother to offspring
• B. From ram to ewe during breeding
• C. From ingestion of contaminated feed
• D. In utero from the ewe to the fetus

Answer: (A)

The main idea is that scrapie in sheep is most commonly acquired by newborn lambs from exposure to infectious placental tissues and birth fluids around birth. The placenta can carry prions, and lambs can pick up infection by contacting or ingesting material in the lambing environment or while nursing, even if the dam isn’t directly transmitting the disease to her offspring. Because prions are highly resistant and shed into the birth environment, the lambing area becomes a key exposure site.

While feeding contaminated material can spread scrapie in some contexts, the typical route is exposure to placenta and birth fluids during lambing. In utero transmission can occur, but it is not considered the primary route, and ram-to-ewe transmission during breeding is not the usual pattern.