Zoonotic Diseases in Cats

By Courtney Barnes, BSc, DVM; Krista Williams, BSc, DVM; Ernest Ward, DVM

What is a zoonotic disease?

Zoonotic disease or zoonoses are terms used to describe an infection or disease that can be transmitted from an animal to a human.

Are there many zoonoses?

Altogether, well over 100 diseases can be transmitted from animals to humans, although most are rare in North America. All domestic animals, including dogs, cats, birds, horses, cows, sheep, goats, and rabbits can potentially spread diseases to people, but it rarely occurs. Most of these potential diseases can be avoided If pet owners exercise basic hygiene principles, especially hand washing.

Am I at risk for contracting a zoonotic disease from my cat?

Current evidence supports the fact that pet cats pose a minimal zoonotic risk to their human companions. Cats kept indoors are exposed to fewer diseases that can be transmitted to humans. Risk may be slightly higher in people with a compromised immune system from disease or medications, such as:

  • people with AIDS/HIV
  • people on chemotherapy or receiving radiation therapy
  • people who are elderly or have chronic diseases
  • people born with congenital immune deficiencies
  • people who have received organ or bone marrow transplants
  • people who are pregnant (the fetal immune system is not fully developed, and the pregnant woman's immune system is altered during pregnancy)

If you fall into one of these categories, it does not mean you have to give up your pet. It simply means that you should take some precautions, such as monitoring your cat for any signs of illness, washing your hands after extensive handling of your cat, and avoiding direct contact with your cat's feces and urine.

It is important to keep in mind that numerous studies prove the benefits of having a pet far outweigh the risks. Sharing your home with a pet is often just what your doctor ordered.

What are the most common zoonotic diseases of cats?

The most common zoonotic diseases include the following:

  • ringworm
  • toxoplasmosis
  • salmonellosis
  • campylobacter infection
  • Giardia infection
  • cryptosporidium infection
  • roundworms
  • hookworms
  • cat scratch disease
  • rabies

What zoonotic diseases are the most likely to cause serious illness in people?

Zoonotic diseases most likely to cause serious illness in people include:

  • Rabies, caused by a virus, is almost invariably fatal in humans.
  • Cats can occasionally be the source of intestinal ailments, including some bacterial infections caused by Salmonella and Campylobacter, as well as intestinal parasites such as Giardia and Cryptosporidium. These diseases can be spread to people by direct contact with the feces of an infected cat or by contact with soil that has been contaminated by the feces of an infected cat. Many other animals also carry these infections. Salmonella and Campylobacter are most often spread through undercooked meat or improperly prepared food.
  • Roundworm and hookworm larvae can cause a condition called larval migrans, where the larvae migrate through various body tissues, causing inflammation. Direct handling of infected cat feces containing eggs can potentially cause an infection in a susceptible person.
  • Ringworm, a fungal infection caused by the fungus Microsporum canis, is relatively easily transmitted through direct contact. It can cause red, itchy, scaly skin lesions.
  • Toxoplasmosis is caused by the parasite Toxoplasma gondii. It is most often contracted by eating undercooked meats, but exposure to infected cat feces can also be a cause. The main risks are to immunosuppressed people and pregnant women, as it can lead to miscarriage and birth defects.
  • Cat scratch disease is caused by a bacteria called Bartonella henselae that is transmitted by fleas. It can be spread from a scratch or bite wound, from flea dirt (feces) or potentially from the fleas themselves. It can cause fever, swollen lymph nodes, and red bumps on the skin.

What can I do to reduce the risk of contracting a disease from my cat?

Proper litter box cleaning is the most effective way to reduce the risk of contracting a disease from your cat. Here are simple guidelines you should follow if you fall into a risk category:

  • Place your litter box away from the kitchen and other areas where you prepare or store food.
  • If possible, have someone who is not at risk clean the litter. Otherwise, clean the litter box daily, since the organism that causes toxoplasmosis takes at least 24 hours to become infectious.
  • Do not dump the litter. If you dump litter, you could potentially aerosolize an infectious agent and inhale it. Be sure to slowly pour the litter into the waste bin.
  • Clean the litter box at least twice a month with hot water, letting the hot water stand in the box for at least five minutes. This simple cleaning technique will kill the toxoplasma organism.
  • Wear disposable gloves and discard them after each use. Thoroughly wash your hands after cleaning the litter box.

How do I know if my cat has a zoonotic disease?

Cats that carry one of these infections will sometimes, but not always, have loose stools or diarrhea. Newly acquired cats are at a higher risk and should have their feces tested by your veterinarian as soon as possible. Cats with skin problems should be examined by a veterinarian right away. Many cats do not show overt symptoms of certain diseases, such as toxoplasmosis or cat scratch disease, so speak to your doctor if you have any health concerns following exposure to cat feces or cat scratches or bites.

What happens if I get one of these diseases?

This group of bacterial and parasitic infections will usually only produce temporary symptoms in someone with a healthy immune system. For people who are immunocompromised, however, some of these infections can be life threatening. Ringworm can be stubborn but is curable with persistent treatment.

How can I prevent my cat from getting bacterial infections and intestinal parasites?

Preventing these diseases is easier than you think. Some simple guidelines to keep your cat healthy are:

  • Feed your cat a high-quality commercial cat food.
  • Avoid raw meat, poultry, and eggs. If you must feed these items, cook them well.
  • Wash hands thoroughly after handling raw meat.
  • Keep your cat indoors and prevent it from hunting.
  • Keep your cat away from other cats and have any new cats examined by your veterinarian before exposing them to existing cats.
  • If your cat goes outdoors, use broad-spectrum deworming as well as flea and tick prevention products on a regular basis, as recommended by your veterinarian.

Can I get HIV or AIDS from my cat?

No, numerous studies prove that you cannot contract HIV/AIDS from your cat. Both feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) are contagious between cats, but neither of them can infect humans, nor can the human virus infect cats.

However, FeLV and FIV suppress the cat's immune system, making them more susceptible to zoonotic infections, which could then be passed on to you. If you are immunocompromised, it may not be healthy to keep a cat infected with FeLV or FIV. If you do keep a cat with one of these diseases, be extra cautious and carefully follow general hygiene and litter box guidelines. To minimize the risks of your cat contracting FeLV or FIV, keep them indoors. If your cat goes outdoors, have her tested and examined at least once a year by your veterinarian.

Can I transmit disease to my cat?

Transmission of disease can occur from people to cats. Common examples include certain viral respiratory infections, ringworm, MRSA bacteria, and fleas. Additionally, gastroenteritis due to Campylobacter and Salmonella infections can be passed from an infected family member to the family cat. Like people, immunosuppressed cats would be at a greater risk.

While technically not zoonotic diseases spread from cats, there are a number of vector-borne diseases that can be transmitted to both cats and humans. Examples include Tularemia spread by ticks, and Bartonella spread by fleas. Ticks, fleas, mosquitos, and flies are all considered potential vectors. Many diseases are regional and tropical climates have higher prevalence, but this can shift over time due to climate change and other factors.

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