What Parasite Do Cats Give Humans?


Parasites are organisms that live on or in a host organism and get their food from or at the expense of the host. There are several types of parasites that cats can pass on to humans that can cause disease and illness. The purpose of this article is to provide information on the most common parasites transmitted from cats to humans, including toxoplasmosis, hookworms, roundworms, tapeworms, and fleas. We will cover the transmission, symptoms, diagnosis, treatment, and prevention of these parasitic infections.

One of the most well-known cat parasites that can infect humans is the protist Toxoplasma gondii, which causes the disease toxoplasmosis. T. gondii is found in cat feces and can be spread through contact with infected cats or environments contaminated with cat feces. Up to one third of the global human population is estimated to carry a T. gondii infection. Most infections produce no symptoms, but the parasite persists for life and can reactivate. We will cover toxoplasmosis transmission, epidemiology, and health effects in more detail later in this article.


Toxoplasmosis is a parasitic disease caused by Toxoplasma gondii, a single-celled parasite that can infect most animals, including cats, dogs, and people (source). Cats become infected by eating prey animals like rodents or birds that have cysts containing T. gondii in their tissues (source). These cysts survive passage through the cat’s stomach and intestinal tract, allowing the parasite to multiply and form oocysts that are shed in the cat’s feces.

Although most cats that ingest T. gondii will not show signs of illness, some may develop diarrhea or lethargy. The main public health concern is due to oocyst shedding. Oocysts in soil can survive and infect humans through ingestion of unwashed produce or gardening without gloves. Oocysts can also contaminate water or food sources. Humans may develop flu-like symptoms, blurry vision, or in severe cases damage to the brain, eyes, or other organs if infected.


Hookworms are parasitic roundworms that infect the small intestine of cats (https://www.petmd.com/cat/conditions/infectious-parasitic/hookworms-cats). There are two main species that infect cats – Ancylostoma tubaeforme and Ancylostoma braziliense. Hookworms attach themselves to the intestinal wall and feed on blood, causing anemia, diarrhea, and weight loss.

Cats typically get infected by hookworm larvae when walking through contaminated soil or sand where another infected animal has defecated. The larvae can penetrate through the skin and migrate to the intestines where they mature into adults worms. Cats may also become infected by ingesting an infected rodent.

Cats spread hookworms by shedding eggs in their feces into the environment. Humans can pick up hookworm larvae by walking barefoot through contaminated soil. Hookworms cannot mature or reproduce in humans, but the migrating larvae can cause a skin rash called cutaneous larva migrans.


Roundworms are parasitic worms that live in a cat’s intestines. The scientific name is Toxocara cati. Cats typically get infected with roundworms by eating rodents or birds infected with roundworm larvae (https://www.petmd.com/cat/conditions/infectious-parasitic/roundworms-cats). Roundworm eggs are also passed from mother cats to kittens before birth or through nursing. The eggs can survive and infect other animals long after being shed in the feces (https://www.smalldoorvet.com/learning-center/medical/roundworms-in-cats/).

Cats with roundworms can shed eggs in their feces, contaminating soil or surfaces. Humans, especially children, can accidentally ingest infective eggs by putting contaminated materials in their mouth. In humans, roundworm larvae migrate through tissues and can cause eye and organ damage (https://www.webmd.com/pets/cats/what-to-know-about-roundworms-in-cats).

Symptoms of roundworm infection in humans include cough, fever, abdominal pain, asthma, and eye inflammation. However, most people show no symptoms. Left untreated, serious organ damage can occur.


Tapeworms are intestinal parasites that attach themselves to a cat’s small intestine and feed off the partially digested food. Cats become infected with tapeworms after ingesting infected fleas or small animals that carry tapeworm larvae such as mice and birds. The most common tapeworm species that infect cats are Dipylidium caninum, Taenia taeniaeformis, and Echinococcus multilocularis.

Tapeworms are flat, segmented worms that can grow up to 20 inches long inside a cat’s intestine. As the adult worms mature, they shed segments containing eggs that are passed in the cat’s feces. These segments look like grains of uncooked rice. Cats often lick their fur while grooming and ingest these infective eggs, continuing the tapeworm lifecycle.

While tapeworms themselves rarely cause illness in cats, they can sometimes lead to intestinal blockages if a heavy worm burden is present. More concerning is that tapeworm eggs shed in the feces can infect humans through accidental ingestion. Children are especially at risk by ingesting infective eggs after contacting contaminated soil or pet fur. In humans, tapeworm infection may cause mild abdominal pain, loss of appetite, weight loss, vomiting, and diarrhea. The tapeworm species E. multilocularis can lead to a more serious disease called alveolar echinococcosis in humans if left untreated.

To protect family members, especially young children, prompt deworming and flea control is recommended. Tapeworm infection in humans is readily treated with medication prescribed by a doctor once diagnosed. Preventative measures include washing hands frequently, stopping cats from hunting prey, and preventing access to feces in litter boxes.


Fleas are some of the most common external parasites found on cats. The most prevalent species that affects cats and humans is the cat flea (Ctenocephalides felis). Fleas can carry and transmit several diseases to humans, including flea-borne typhus, plague, and cat scratch disease [1]. Some of the symptoms humans may experience from fleas include itchy rashes, hives, and infection at the site of flea bites.

Fleas can transmit a number of diseases to humans through infected flea feces. When an infected flea bites a human or cat, it can transmit Rickettsia typhi or Yersinia pestis, the bacteria that cause flea-borne typhus and plague, respectively. The flea feces can also contain the bacteria Bartonella henselae, which causes cat scratch disease in humans. This occurs when flea feces on the claws or teeth of a cat contaminate a bite or scratch wound. Cat scratch disease causes swollen lymph nodes, fever, and fatigue in humans.

Flea bites on humans often appear around the ankles and legs in clusters of small, red bumps that may itch intensely. Flea dirt, which looks like black pepper, may also be apparent in areas around flea bites. Humans can also exhibit hives or a rash in response to flea saliva. While flea bites themselves are not typically dangerous, they can lead to secondary infections if the skin is broken from excessive scratching. Therefore, controlling fleas on cats is important to prevent them from infesting human environments.

[1] https://www.goodhousekeeping.com/life/pets/a27199208/how-to-get-rid-of-fleas-on-cats/


There are several ways cat owners can help prevent the transmission of parasites from cats to humans:

Regular deworming – Work with your veterinarian to keep your cat on a regular deworming schedule, usually every 3-6 months. Deworming medications like pyrantel pamoate, fenbendazole, and praziquantel help remove roundworms, hookworms, and tapeworms. https://petlifesa.com/health-wellness/basic-care/parasites/preventing-cat-parasites/

Flea and tick control – Use monthly topical or oral flea and tick preventatives prescribed by your vet. Fleas can transmit tapeworms and also cause flea allergy dermatitis. Ticks can transmit other parasites and diseases.

Litter box hygiene – Scoop feces from the litter box daily and change the litter regularly. Feces can contain parasite eggs that become infectious after a couple of weeks. Keep litter boxes away from food preparation areas.

Wash hands – Wash hands with soap and water after handling cats, cleaning the litter box, or gardening areas cats may have defecated in. Handwashing prevents accidental ingestion of parasites.

Cover sandboxes – Sandboxes can become contaminated with parasite eggs from outdoor defecation. Keep sandboxes covered when not in use.

Control rodents – Prevent access of rodents like mice to cat food bowls and litter boxes. Rodents can spread some parasites to cats.


Testing cats and humans for parasites typically involves examining stool samples. For cats, vets may recommend bringing in a fresh fecal sample for analysis. There are also convenient at-home test kits like the Basic Fecal Test from Affordable Pet Labs that allow cat owners to collect and send samples themselves.

According to the Drake Center, fecal exams check for worm eggs, larvae, or adult worms that may be visible to the naked eye. Tapeworm segments may also be detectable in fecal matter. For humans, doctors can test stool samples or order blood tests to check for antibodies to certain parasites.

Early detection and treatment of parasites is important to stop their spread and prevent severe symptoms. Annual fecal exams for cats and discussions with doctors about parasite testing can help identify issues before they become serious.


There are several medications and procedures available to eliminate cat parasites in both felines and humans. Some of the most common treatments include:

For cats:

  • Topical flea and tick medications like Revolution, Bravecto, and Seresto collars which kill adult fleas and prevent re-infestation.
  • Oral deworming medications like drontal and profender that kill roundworms, hookworms, and tapeworms.
  • Vaccines for diseases like toxoplasmosis.
  • Anti-parasitic shampoos and dips.

For humans:

  • Oral antiparasitic drugs like mebendazole to treat common worm infections.
  • Topical creams and lotions to eliminate scabies.
  • Antihistamines and corticosteroids to reduce inflammation and itching from flea bites.
  • Hygiene measures like frequent hand washing and laundering bedding.

In some cases, infected cats may need to be rehomed temporarily during treatment to prevent reinfection. Regular veterinary checkups and strict flea control are key to preventing recurring parasites.


There are a several common parasites that cats can spread to humans, including toxoplasmosis, hookworms, roundworms, tapeworms, and fleas. Toxoplasmosis spreads through contact with infected feces and can lead to flu-like symptoms or more serious complications. Hookworms, roundworms, and tapeworms are intestinal parasites that are contracted through ingesting eggs in the environment or fleas. Fleas can bite both cats and humans and lead to itchy skin and infections. Luckily, there are precautions owners can take to minimize the risk of contracting these parasites. Keeping cats indoors, cleaning the litter box daily, washing hands after handling cats, controlling fleas, and deworming cats regularly can all help prevent transmission. If symptoms develop, visiting a doctor for a diagnosis and targeted treatment is important. Responsible cat ownership includes being diligent about parasite prevention for the health of both cats and humans.

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