Is Roundworm in Cats Contagious?

A cat with roundworms may not show any outward signs.
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Most cats play host to some form of parasite during their nine lives. Roundworms are long, spaghetti-like worms that happily spend their lives swimming around your cat's intestines. Unfortunately, these freeloaders aren't exclusive to cats and can easily pass to other animals or humans.

Initial Infestation

Roundworms don't magically appear in your cat, even though you may not have any idea how they got there. These pesky parasites find their way into a feline host through ingestion in egg form. This could happen through tainted mother's milk, by grooming after contact with infected poop or soil or by eating an infected prey animal. Once in the cat's intestines, the eggs hatch and the larvae roundworms travel through the cat's innards as they mature. Weeks later, the well-traveled juveniles return to the intestines, where they mature into adults and begin laying their own eggs. These are then shed in the cat's poop or deposited around the cat's bottom to fall off and wait for another unsuspecting host. Thus the roundworm life cycle begins anew.

Symptoms, Diagnosis and Treatment

The frustrating and more than a little disturbing thing about roundworms is you may never know your cat is infected at all. In many cases, a cat with worms wiggling around in his gut may never show any symptoms of the parasite party going on. In fact, the first sign of a problem may be a few long strands of dead worms in your cat's litter box or vomit. Heavy infestations can cause health issues for the cat, as the worms leech away vital nutrients. Diagnosis is easy if you find discarded worms in your daily litter box scoop, or your vet can examine your cat's poop for signs of eggs. A few doses of dewormer medication typically kills the interlopers in your cat's belly, with the corpses of the worms ending up in a tangled mess in the litter box.

Preferred Host

Roundworms are not picky parasites and make themselves at home in cats, dogs and humans alike. An infected cat can pass his pesky squatters to every other member in the household. Feline housemates can ingest eggs from social grooming sessions or by stepping in infected poop during their potty break. Dogs typically become infected by “snacking” in the litter boxes or walking where eggs have dropped off and then swallowing them as they groom. Humans, especially children, usually pick up eggs when they interact with infected dirt or sandboxes and don't wash before touching their mouths.

Stop the Cycle

Even though treatment is fairly simple and straightforward, that doesn't stop the possibility that the infestation may happen again. Give all your pets -- both cats and dogs -- monthly preventive treatments to continually kill any roundworms that may move in, and scoop litter boxes daily to remove any infected poop before the eggs have a chance to find a new host. Thoroughly wash the litter boxes and any possibly contaminated surfaces, such as counters your cat may jump on and pet bedding, with hot water and bleach to thoroughly remove any shed eggs. Wash your hands after working outside in the garden or cleaning the cat boxes to minimize the chance of introducing creepy crawlies into your intestinal tract.

Always check with your veterinarian before changing your pet’s diet, medication, or physical activity routines. This information is not a substitute for a vet’s opinion.

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