Can cat's tapeworms infect human?

Sunday, June 8, 2003


By Dr. John Koch

Question: The other day while petting my cat, I noticed that she had what appeared to be numerous sesame seeds stuck to the hair underneath her tail. While making this observation, I happened to notice that a small worm crawled out of her anus. I have been told that these are tapeworms and that I will need to worm my cat. More than anything else, I am concerned about whether or not these worms are contagious to humans?

Answer: It is possible for people to get tapeworms from pets, but it is very unlikely. By far the most common worm found in mature cats is the tapeworm. These segmented worms attack to the intestinal tract and eat the same food the cat eats. The relationship between the cat and the tapeworm is fairly symbiotic. In most cases the worm causes unthriftiness, but rarely serious illness.

Segments drop away from the end of the attached tapeworm and are passed through the anus and out of the pet's body. These segments are in reality a packet of eggs. After the segment is passed it crawls a short distance and dries into the sesame seed-like appearance you describe. This drying process causes the packet to split apart and the eggs to be released onto the hair of the cat. A flea comes along and ingests the eggs. Inside the flea, the egg hatches and forms a cyst. At some point in time the cat, while grooming itself, swallows the flea with the tapeworm cyst. Once inside the cat the cyst finished its life cycle and developed into an adult tapeworm.

If a human accidentally swallows a tapeworm egg, nothing will happen. In other words, you will not develop tapeworms. However, if you swallow a flea containing tapeworm cysts then you could become infected. Since humans rarely groom themselves by licking their bodies, tapeworm infection in our species is extremely rare in the United States.

The key to controlling tapeworms in pets is controlling fleas. Cats tend to be rather sensitive to insecticide. Not all over the counter flea products are safe and effective. It is advisable to consult with your veterinarian before purchasing worm medications and compounds for defleaing. Long-term flea control will be important because tapeworm eggs are capable of living as long as 15 months in the environment.

Dr. Koch is a Cape Girardeau veterinarian.

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