When people think about troublesome parasites that can infect cats they usually think of heartworms, but those aren't the only microscopic pests that can cause trouble for your cat.  Roundworms are the most common parasitic worms found in both cats and dogs, and since they can be contracted in a variety of ways they can spread fast.  If you give your cat heartgard for heartworm prevention you may be in luck, the popular worming prevention medication also can treat roundworm and hookworm infection.  Pet owners should still learn about roundworm even if they give their pets preventative worming treatments; knowing the signs and symptoms could protect your cat in case they manage to contract them. 
An Easy to Contract Parasite
Cats usually contract roundworms in two main ways. Many kittens with roundworm infections become infected through their mother's milk.  Pregnant female cats with roundworm infections can have larvae present in their mammary glands, and the larvae get passed to the kittens when they drink their mother's milk.  Most cats become infected with roundworms when they ingest the eggs of roundworms, and roundworm eggs are extremely common.  They can ingest eggs from the soil, licking them off their feet after walking on them, or by eating a host animal like an insect or rodent.
What Makes Roundworm Infection So Common?
Roundworms are a strange breed of intestinal worms because of the way they live their lives.  Their unusual amount of mobility is part of what makes these parasites so easy to become infected with and transfer to other living things.  Once the eggs enter the mouth they hatch in the intestines, but once they hatch they like to burrow their way into other living tissues in the host's body.  Unlike other intestinal parasites these worms don't attach to the walls of the intestines, they're literally "swimming" freely within the digestive tract.  Roundworms have been found in the lungs, liver, and even heart.  It's also important to mention that it is possible for other mammals to contract roundworms from cats, including humans.
Signs of Roundworm Infection
Many cats don't show signs of roundworm infection if there are small amounts of the parasite in their bodies.  The ASCPA has a complete list of the signs of roundworm infection and other parasitic infections.  If your cat exhibits any of these symptoms, you should take them to a vet immediately:
  • Diarrhea
  • Worms visible in stool or segments of worm seen near anus
  • Bloody stool
  • Bloating or round, potbellied appearance to abdomen
  • Vomiting
  • Coughing
  • Trouble breathing