Which parasite infects the bile ducts of livestock?

• A. Tapeworms
• B. Liver flukes
• C. Roundworms
• D. Pinworms

Answer: (B)

Liver flukes infect the bile ducts because their adult stage resides in the ducts of the liver, where they feed on blood and cause liver and biliary tract disease. Livestock pick up metacercariae on aquatic plants, the larvae migrate through liver tissue, and then settle in the bile ducts to mature. This localization in the biliary system explains both the pathology and how the parasite is transmitted.

Tapeworms, roundworms, and pinworms primarily inhabit other parts of the digestive tract or associated tissues, not the bile ducts. Tapeworms attach in the intestinal tract; roundworms mainly live in the gut (with some migratory larval stages elsewhere) and pinworms stay in the distal intestine and perianal area.