Worms are a common parasite that almost all cats will experience at some point in their lifetime. The most prevalent intestinal worms to infect cats are roundworms, hookworms and tapeworms. These parasitic worms live in the gastrointestinal tract where they feed on nutrients that pass through the cat or in the case of hookworms, they attach to the intestinal wall and feed on the cat’s blood.
Intestinal worms carry the risk of zoonotic disease, that is, they can potentially infect humans.
How do cats get worms?
Each worm has its own mode of transmission, but all worms have evolved highly effective ways to infect their new host. Parasite eggs pass out of the body via the cat’s stool, from there they have different modes of infection. Adult cats, especially those who hunt are at increased risk, however, indoor cats can catch worms as eggs or infected cat fleas can be brought into the house on shoes or clothing.
The cat flea acts as an intermediate host in the tapeworm (dipylidium canium) life cycle. As the cat grooms, he or she ingests an infected flea, once inside the gastrointestinal tract, the flea breaks down, and the tapeworm is released where it matures into an adult. The adult tapeworm is made up of a chain of segments, each of which is self-sufficient and complete with male and female reproductive organs. Mature segments full of fertilised eggs (proglottids), detach from the tapeworm and pass out of the cat’s body via the feces. Pet owners may notice proglottids around the anus of cats, which have the appearance of grains of rice. Once in the environment, the proglottid desiccates, and the eggs are released. Flea larvae feed on the tapeworm eggs (which look like sesame seeds), ingest the infective larvae which remain with the flea into adulthood. If the cat has a flea infestation, there is a high chance he or she also has tapeworm.
Cats can also develop taenia taeniaeformis tapeworm from eating rodents infected with tapeworm larvae.
Roundworm infections (toxocariasis) are the most common gastrointestinal parasites in cats. The two roundworm species to infect cats are Toxocara cati and Toxascaris leonina.
Infection can occur via ingestion of infective roundworm eggs in the environment where they can remain viable for months or years, by ingesting prey infected with encysted roundworms in their tissues, or via the mother’s milk.
Most adult roundworms live in the gastrointestinal tract of their host. When the cat ingests embryonated eggs, they hatch in the intestine, penetrate the intestinal wall, and migrate through the liver to the lungs. From there they enter the alveoli and travel up the airways. Larvae in the pharynx are swallowed and reach the intestines once again where they mature into adults, mate and release their eggs. A single roundworm can lay up to 200,000 eggs a day. Roundworm eggs are not immediately infective, but take 2-4 weeks to reach third-stage larvae (L3), at which point they become infective if ingested.
If an adult ingests roundworm larvae, some may penetrate the intestinal wall but fail to migrate to the lungs. Instead, they travel to tissues and organs and become dormant hypobiotic larvae. Pregnancy can re-activate these encysted roundworms which migrate to the mammary glands and pass into the kittens via breast milk.
The hookworm (Ancylostoma ceylanicum, A. braziliense, A. tubaeforme and Uncinaria stenocephala) can infect cats in a number of ways.
- Skin penetration (percutaneous): When a cat comes into contact with an environment infected with hookworm larvae which can penetrate the skin, from there, they migrate to the intestine where they mature.
- Ingestion or inhalation: Cats can also become infected by ingesting infective third-stage larvae of uncinaria in the environment, during grooming or via contaminated water and food.
- In utero: Worm eggs may be passed on from the mother to her unborn puppies via the placenta. It hasn’t been established if this is the case with feline hookworms yet.
- Transmammary: It is possible to pass hookworm to puppies via breast milk, but it is not known if kittens can become infected the same way. When a dog becomes infected with hookworms most of them migrate to the small intestine. However, some enter other tissues of the body, where they remain dormant for years. During pregnancy, they reactivate, migrate to the mammary glands and out through the milk.
Cleaning a house after cat worms
Decontamination is essential to prevent reinfection or transmission to humans. Most worm eggs are resistant to chemical disinfection such as bleach. Their sticky outer coating makes them difficult to remove from surfaces, and eggs can survive for years under the right conditions. The only effective way to kill parasitic worm eggs is with extreme heat or steam.
- Rubber gloves
- Face mask
- Dishwashing detergent
- Warm water (for detergent)
- Boiling water
- Sponge, with a scourer
- Paper towels
- Vacuum cleaner
- Steam cleaner
Always wear rubber gloves and a face mask (preferably N95) when handling litter trays and decontaminating the home.
- Wash all cat bedding, human bedding, throws, and cushion covers in hot water and hang outside in the sun to dry. Be careful not to shake blankets or sheets to avoid spreading worm eggs into the air.
- Vacuum the home thoroughly including underneath furniture, and along skirting boards.
- Scrub all hard surfaces (floors, kitchen benches) with hot soapy water to dislodge worm eggs and remove as much organic debris as possible. Pay attention to areas the cat likes to hang out such as sleeping spots, litter trays and food bowls.
- Completely empty litter boxes and scrub with warm water and detergent. Pour boiling water into the litter tray and litter tray scoops and allow it to sit for ten minutes.
- Scrub rubber or plastic cat toys and soak in boiling water for ten minutes.
How to remove the vomit or feces of a cat with worms
Cats with heavy worm infections can pass roundworms in their vomit or stool which is an alarming sight for most of us.
- Lightly mist the vomit or feces to avoid stirring up debris.
- Wear rubber gloves and use paper towels or old newspapers to clean as much of the vomit or feces as you can. Place it into a plastic bag and dispose of it in the outside garbage.
- If the vomit or feces was old and has dried, spray with detergent and allow to sit on the stain for five to ten minutes to soften it. Fill a bucket with hot, soapy water and use a damp sponge to scrub the area. Rinse and repeat. Blot dry with paper towels. Dispose of the sponge and paper towels in the garbage.
- Remove as much vomit or fecal matter as you can with paper towels first.
- Use a suitable carpet or upholstery cleaner to remove the remainder of the stain. Always follow instructions on the packaging. If you don’t have carpet or upholstery cleaner, spray with household cleaner or detergent, and scrub the area well, blotting periodically and scrubbing again. Use paper towels to remove any remaining moisture.
- Once the area has been cleaned, steam clean to kill any eggs which may have contaminated the area.
Signs of worms in cats
Adult cats are often asymptomatic unless they are kittens or heavily infested. Common symptoms of worms include weight loss, pot-bellied appearance, unkempt coat and stunted growth in young kittens. Extreme cases may also have roundworms in the vomit or feces.
Can humans catch worms from cats?
Humans can catch roundworms from cats, however, the roundworm species that most commonly affect cats (Toxocara cati and Toxascaris leonina) can’t go past stage 3 development. Larvae migrate through the skin (cutaneous larva migrans) and can move to various tissues in the body (visceral larva migrans), including the lungs, brain, eyes, and liver. Larvae can remain alive for many months, causing inflammation as they migrate through the tissues.
- Cutaneous larva migrans (CLM): Larvae penetrate the skin and migrate under the skin surface causing itchy red
- Ocular larva migrans (OLM): The larvae enter the eye, which leads to an inflammatory and damage to damage to the eye; in severe cases, blindness.
- Visceral larva migrans (VLM): The larvae migrate to the various organs and cause an (inflammatory immune response), which leads to damage.
Reducing the risk of transmission
Prevention is always better than cure and households with pets should always practice routine measures to reduce the risk of parasitic worm transmission.
- Cover sandboxes when not in use.
- Remove urine and cat feces from the litter tray on a daily basis. Once a week, litter trays should be emptied, scrubbed, disinfected with a weak bleach solution (allow to sit for ten minutes and rinse), and re-filled with fresh litter.
- Discard dirty cat litter in the outside bin. Do not put on gardens, especially not where food is grown.
- Regularly treat all cats and dogs for intestinal worms and fleas. Veterinary deworming medications are a much more effective treatment than over the counter products.
- Always wash hands with warm soapy water after cleaning litter trays, cat bedding and animals.
- Discourage your cat from defecating in the garden by providing adequate litter trays inside the home. As a rule, there should be one litter tray per cat, plus one extra. If the cat does go to the toilet outside, remove feces where possible.
- Always wear shoes when outside if there is any chance a cat or dog has defecated in the area.
Frequently asked questions
Can I touch my cat if he or she has worms?
You can touch your cat as long as he or she has been recently treated for worms and always wash your hands afterwards.
Can cat worms live in the carpet?
Adult worms cannot live in the carpet, but worm eggs can survive in the environment (including carpet) for months or years. This highlights the importance of thoroughly cleaning the house, including steam cleaning carpets and rugs.
What home remedy can I use to deworm my cat?
There are no safe or effective home remedies. The only way to kill intestinal worms is with a veterinary-approved medication.