A dog becomes infected with Dipylidium caninum by ingestion of which?

A dog becomes infected with Dipylidium caninum by ingestion of which?

• A. Infected fleas
• B. Saliva from an infected dog
• C. Feces from an infected dog
• D. Tissues of an infected rabbit

Answer: (A)

Dipylidium caninum requires an intermediate host to complete its life cycle, and the dog becomes infected by ingesting an infected flea that harbors the cysticercoid larva. When a dog grooms and swallows such a flea, the cysticercoid attaches to the lining of the small intestine and develops into the adult tapeworm, which then sheds proglottids in the feces. This is why simply swallowing saliva, feces, or rabbit tissues won’t cause infection—the parasite needs the flea to carry the infectious stage. Controlling fleas reduces the risk because it interrupts that essential step in the parasite’s life cycle.

Dipylidium caninum requires an intermediate host to complete its life cycle, and the dog becomes infected by ingesting an infected flea that harbors the cysticercoid larva. When a dog grooms and swallows such a flea, the cysticercoid attaches to the lining of the small intestine and develops into the adult tapeworm, which then sheds proglottids in the feces. This is why simply swallowing saliva, feces, or rabbit tissues won’t cause infection—the parasite needs the flea to carry the infectious stage. Controlling fleas reduces the risk because it interrupts that essential step in the parasite’s life cycle.