Roundworms are a common intestinal parasite of cats, as well as dogs. Cats are infected with two species of roundworms, one of which is transmissible to dogs.
Most commonly, cats get roundworms from infected water, food, or by eating rodents. Mother cats are able to pass the infection through their milk, so it is not uncommon for very young kittens to test positive.
After ingestion, the larvae migrate through the intestinal wall, into the liver, then the lungs, where they are then coughed up and swallowed. These larvae then infect the small intestine and some can encyst in the muscle tissue of cats.
The prepatent period (the time from ingestion to infection) is eight weeks. Clinical signs in adults are rare, but are more common in kittens. Signs are usually mild and include vomiting, diarrhea, weight loss, poor growth and a pot-bellied appearance. Very rarely, severe infections can cause intestinal obstruction and perforation.
This is an easily diagnosed condition and is easily treated as well. There is also zoonotic potential- meaning that humans can become infected. The eggs of roundworms are very hardy, so good mechanical removal from the environment is essential. It is currently recommended that kittens be dewormed every two weeks, and adults 3-4 times a year. Most topical flea preventatives also target these parasites.