The most common intestinal parasite found in cats, roundworms most often infect kittens and outdoor animals. Adult cats can become infected by eating small animals that harbor the parasite or by licking their paws after walking on soil contaminated with the infective roundworm larvae. While adult cats usually have no notable signs of infection or very mild symptoms, kittens -- who usually get the worms while nursing from an infected mother cat -- are likely to develop gastrointestinal problems, such as vomiting and diarrhea. Additional serious complications may occur when the roundworms, or ascarids, migrate within the wall of the gastrointestinal tract or through other organs, such as the liver, lungs, and eyes. Roundworms are treatable with medication.
There are two species of the ascarid that infect cats, Toxocara cati and Toxocara leonina. The Toxocara cati roundworm also can affect humans, particularly young children who come into contact with the parasite when playing in a sandbox contaminated with feces from an infected cat; outdoor cats often use a sandbox or other area of loose soil as a litter box. While direct contact with an infected cat is not likely to lead to human exposure to the disease, litter boxes should be cleaned out daily so that any roundworm eggs shed into the feces will not pose a danger.
Humans who become infected with roundworms can suffer severe symptoms, including skin rash, fever, abnormalities of the central nervous system, coughing, enlargement of the liver or spleen, and vision problems such as blindness. Although human infections are rare, all kittens should be dewormed to prevent transmission of the parasite. Outdoor cats should have a periodic test for worms and be treated as needed.
