Trichodectes

TRICHODECTES, Trichodectes, an insect of the order Mallophaga; has no wings, mouth parts are gnawing; lives on mammals, feeding on hair and desquamating scales of the keratinized epidermis. Spends its entire life, starting from the egg, on the host. Its flat body with an angular head is adapted to remain in the host's fur. Tr. canis parasitizes on dogs, Tr. subrostratus lives on cats. Cows, goats, sheep, and other mammals have their own parasites of the same genus. Medically significant are the dog and cat biting lice. By feeding on their hosts' hair, these biting lice swallow the eggs of the cucumber-like tapeworm (Dipylidium caninum), which often parasitizes the intestines of dogs and cats. The animal's fur easily becomes contaminated with the eggs of this worm from the host's feces. In the intestine of the Trichodectes, the oncosphere emerges from the egg, passes into the body cavity of the insect, and here transforms into a cysticercoid. For D. caninum, this fact was discovered by Melnikov; the natural infection of the cat's Tr. subrostratus with cysticercoids was discovered by E. K. Brandt. Trichodectes causes itching in its host. The dog scratches itchy areas of skin with its teeth, easily crushing and swallowing infected Trichodectes. From their cysticercoids in the dog's intestine, the adult worm develops. Since both hosts, the definitive and intermediate, live on each other, invasion by parasites is facilitated. Usually Dipylidium caninum is present in the intestine of its host in large numbers. If a person swallows a biting louse with cysticercoids, the latter also transform into adult worms (accidental parasitism).