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Pet Parasites and People


Did you know that between 1 and 3 million people in the United States are infected with dog and cat roundworms every year? Many suffer from flu-like symptoms, but over 700, mostly children, suffer blindness or permanent visual impairment as a result.

Many parasites, including roundworms, hookworms, and Giardia, are infectious to people as well as pets. In dogs and cats, roundworm eggs hatch in the intestine. The larvae then migrate through the intestine into the abdominal cavity, feeding on tissue as they go. Then they travel through the liver and into the lungs. The larval worms are coughed up and swallowed, returning to the intestines to grow into adult worms and shed eggs in the stool for the next animal to pick up. In people, the larvae get confused because we aren’t their natural host. They may end up in the brain, spinal cord, or eyes, instead of the lungs.

Hookworm larvae get into a pet by burrowing into the skin of the paws or feet. They will do this in people, too, but again they get lost. They usually burrow for a while in the skin and underlying tissue, causing a severe rash and disfiguring scars. Since children are more likely to be outside barefoot, they are most frequently affected.

Giardia are one-celled protozoal parasites, not worms. They survive for a long time in ponds, streams, puddles of water, or damp soil. They are shed by dogs, cats, deer, and many other animals, and are contagious to people as well. It has been estimated that nearly 36 to 50 percent of puppies, 10 percent of adult dogs, and up to 100 percent of dogs in breeding kennels are infected with Giardia, which causes vomiting and diarrhea in both people and pets. A new vaccine for Giardia has come on the market recently and may be recommended for owners who breed their pets or whose dogs swim frequently.

Intestinal parasites are serious threats to pets and family members alike. We know it’s not much fun to pick up a pet’s poop and bring it to the veterinary clinic. However, it’s one of the most important things you can do to keep both your pets and your family members safe and healthy. We would also like to remind you to thoroughly wash your hands after cleaning your cat’s litter pan, cleaning your dog’s stool from the yard, or after gardening. Wash your children’s hands as well when they come in from the yard. Pick up stool from your grass often, and check children’s sandboxes for stool from outdoor cats before they play in it (or better yet, keep the sandbox covered when it’s not in use.)

All dogs and cats should have a fecal exam at least once a year. The more a pet is exposed to other pets (at a dog park or training class, for example), the more often testing is recommended. Twice-yearly stool checks are a good idea for dogs with high exposure. Outdoor cats, or those who hunt and eat rodents and birds, should be checked or dewormed frequently. Younger and elderly pets are at higher risk of becoming ill from parasites, so puppies, kittens, and senior pets should also be checked more often.

If your veterinary clinic does find parasites in your pet’s stool, they will prescribe the most effective medication available to treat the problem. Pets with a heavy parasite infestation may be thin, mopey, have dry skin and dull haircoats and suffer from vomiting and diarrhea. Hopefully, you won’t let it go that far! Bring those samples in today!