Cats are hosts for two types of tapeworms: Taenia taeniaeformis, which infects many small wild mammals, and Dipylidium caninum, which can also be caught by dogs. Humans can be infected with Dipylidium caninum, but are not natural hosts for Taenia taeniaeformis. Young children are most at risk for catching tapeworms from cats. Prevention, diagnosis and treatment is fairly simple.
Fleas are the intermediate hosts for Dipylidium caninum, and the cat swallows them while grooming, or by eating an infected rodent. The tapeworm microfilaria pass through the digestive system, attaching to the intestinal walls where they grow and reproduce. Small, egg-filled segments called proglottids break away from the tapeworm and are expelled through the anus.
Taenia taeniaeformis is found in the muscle tissue and organs of small mammals and cats usually get these tapeworms by eating mice.
How Humans Get Cat Tapeworms
Taenia taeniaeformis has been recorded in humans but is extremely rare. In order to get it, a person would have to eat raw, infected meat. Even then, humans are not natural hosts; the tapeworm microfilaria are unlikely to attach.
Children are more likely to get Dipylidium caninum than adults, through interacting with a cat. In order to be infected with this tapeworm, a human has to swallow either an infected flea, a proglottid or viable tapeworm eggs.
The symptoms of tapeworms are similar in both cats and humans: Mild diarrhoea, stomach upset and rectal itching from the emerging proglottids. There may be no symptoms at all if the infestation is limited to one or two worms. Diagnosis is confirmed by the presence of proglottids in the stool or underwear, around the anus or on furniture and bedding. These look like flattened grains of rice and disconcertingly enough, may still be moving.
Treatment is simple. It usually requires a single oral dose of praziquantel (called Biltricide for human use; Droncit for animals). This kills the tapeworms within 24 hours. In heavy or persistent infestations, a second oral dose, or a praziquantel injection, may be administered.
Flea control is the most important step in preventing tapeworms in both pets and humans. Use a veterinarian-prescribed topical flea preventive every 4-6 weeks if your cat goes outside. None of the topical treatments or regular wormers prevent or kill tapeworms. Talk to your veterinarian about prophylactically dosing your cat with Droncit once or twice a year if she is an avid hunter.
Even with preventive, cats can get tapeworms through hunting and eating infected prey. Be alert to signs of tapeworms in the stool. If the cat (or a child) seems to have an itchy bottom or the cat is grooming excessively, stay alert for signs of proglottids.