Fleas play a necessary role in the life cycle and
reproduction of a certain type of tapeworm called Dipylidium caninum.
Humans can also be infected with Dipylidium caninum, but cats and dogs are
the primary hosts cause cats and dogs more often swallow a flea.
The adult form of the tapeworm Dipylidium caninum lives in the small
intestines of dogs and cats. The worm is made up of multiple segments. One at a
time, the segments, full of eggs, are passed in the feces. While warm, the
segments are active, but as they dry, they break open and liberate the eggs
inside. A flea larva
ingests the eggs. The egg develops into an immature form in the flea. When a dog
or cat eats the flea (usually while the animal is grooming), the immature form
of the tapeworm is released from the flea. This immature tapeworm then develops
into an adult in the dog's or cat's intestine and the life cycle is
The tapeworm D. caninum can not be passed directly from cat to cat
or dog to dog. It must live part of its life in the flea.
Pets may be infected with other types of tapeworms in which the larval form
of the parasite can be found in rodents, pigs, or fish, instead of