Worms That Infect Cats and Can Infect People

You usually don’t see them, but they are there. Where do they come from, what clinical signs can they cause in you and your cat, and (most importantly) how do you make them go away?

Roundworms are the most common intestinal parasite. Cats and kittens acquire the infection by eating parasite eggs, eating transport hosts (mice) or by nursing an infected mother. Children acquire the infection by ingesting contaminated soil. Infected kittens may show signs of coughing, diarrhea, poor growth or abdominal distention. In some people, the larva of this parasite migrates to the eyes or nerves and produces permanent eye damage. Wandering larva may produce no symptoms in people, and many cats show no signs of disease. Because this parasite is so common and there is a potential for severe disease, we recommend treating all new cats and all outdoor cats for this parasite. The medication is inexpensive, safe, efficacious and easy to administer.

Hookworms are very small worms (9-15mm) that can live as long as the cat. People and cats become infected by ingestion of parasite eggs or by the larva that penetrates skin. In cats these parasites attach to the lining of the intestine and can produce significant blood loss. People who are exposed to contaminated soil can develop red, itchy skin lesions when the parasite tries to migrate though their skin. Recent reports have also connected infection with this parasite to human intestinal disease.¹ Fortunately, there are excellent medications for this parasite for both people and cats.

Tapeworms are the parasites that are most frequently seen by owners. The segments are about ¼” long and resemble grains of rice when fresh and sesame seeds when dry. They are usually found under the cat’s tail or on its bedding. These segments are not infective. Most tapeworms require an intermediate host to become infective. Fleas and rodents are the intermediate host for common cat tapeworms. Cats are infected when they swallow fleas containing tapeworm larva. Cats who hunt may be infected when they eat rodents. Most cats show no signs of infestation. The two common feline tapeworms may be transmitted to people by accidental ingestion of the intermediate host but cause only mild disease. Other tapeworms cause serious disease in people. The pharmaceuticals that kill tapeworms are different than those for roundworms and hookworms. The current medications are very effective. Control of the intermediate hosts (fleas and rodents) will prevent infection.

Roundworms, hookworms and tapeworms are easily treated. They pose a heath risk to our cats and families. All kittens and newly acquired cats should be treated for these common intestinal parasites. If a cat lives outside and hunts he should be treated at least yearly and perhaps even more frequently. By following these guidelines you can reduce the transfer of these parasites to cats and people.

¹ Schantz, P.M.; Zoonotic Ascarids and Hookworms: The Role for Veterinarians in Preventing Human Disease. Supplement to Compendium on Continuing Education for the Practicing Veterinarian. 24:47-52, 2002