Zoonotic Diseases of Cats

Zoonotic diseases are those that can be transmitted from animals to humans. Cats can carry and transmit several zoonotic diseases, some of which can be serious or even life-threatening. It is important for cat owners to be aware of these diseases and to take steps to prevent transmission to humans.

Some common zoonotic diseases that can be transmitted from cats to humans include:

Toxoplasmosis: This disease is caused by the parasite Toxoplasma gondii and is commonly transmitted through contact with infected cat feces. It can cause symptoms such as fever, muscle aches, and swollen lymph nodes in humans.
Ringworm: This fungal infection can cause skin lesions and hair loss in cats and can be transmitted to humans through direct contact with an infected cat or through contact with contaminated objects.
Bartonellosis: This bacterial infection, also known as cat scratch disease, is transmitted through bites or scratches from an infected cat. It can cause fever, swelling, and redness at the site of the scratch or bite.
Salmonellosis: This bacterial infection is transmitted through contaminated food or water and can cause symptoms such as diarrhea, fever, and abdominal cramps in humans. Cats can carry the bacteria and transmit it to humans through contaminated feces.

It is important to practice good hygiene when handling cats, including washing your hands after handling them or their litter boxes and avoiding contact with their feces. In addition, it is important to keep your cat up to date on their vaccinations to help prevent the transmission of zoonotic diseases. If you have any concerns about zoonotic diseases or the health of your cat, it is important to consult with a veterinarian.

The following are some of the more common and well-known diseases that cats can transmit to people. It is also important to remember that many of these pathogens may be carried by a cat without actually making the animal sick, and may therefore go undetected.

Infections that cause diarrhea:

These include the bacteria Campylobacter jejuni and Salmonella sp., and the protozoa Cryptosporidium sp. and Giardia intestinalis. All of these are notifiable diseases in people in Canada.

They may cause no illness at all, or they may cause diarrhea, or in higher-risk individuals (e.g. HIV/AIDS, transplant, cancer patients, young children) they may cause much more serious illness. They are transmitted by contamination of food or water that is ingested, or stool contamination of the hands which is transfered to the mouth.

Cat scratch disease (bartonellosis, benign lymphoreticulosis, bacillary angiomatosis):

An infection caused by a proteobacterium, Bartonella henselae, which infects up to 40% of cats, but does not make cats sick. It is believed to be transmitted to people when a bite or scratch from a cat is contaminated by the cat’s blood or flea excrement (which contains digested blood) from an infected cat.

Infection often causes fever and very swollen lymph nodes, but it can be more serious or even fatal in immunocompromised individuals.

Other cat bite wound infections:

It is estimated that 20-50% of cat bite wounds become infected. Usually multiple kinds of bacteria are present in each wound and infection can be very severe.

Cat bites can also create deep puncture wounds which may result in infection of deeper tissues such as bones and joints.

Larval migrans caused by hookworm and roundworm larvae:

This condition can be caused by various species of hookworms and roundworms, some of which infect cats. Eggs of the parasites are passed in the stool of infected animals, and release larvae which can penetrate a person’s skin or are accidentally ingested.

The larvae then migrate under the skin (cutaneous), through various internal organs (visceral) and occasionally the eye or brain (ocular or neurological), causing irritation and inflammation (larval migrans). The ocular form can result in blindness. Infection is most likely to occur in young animals and children.

Rabies:

A viral infection of the nervous system which is almost always fatal once clinical signs appear. Cats are usually infected by direct contact with a rabid animal, most often a skunk, fox, raccoon or bat.

Transmission occurs when the saliva of an infected animal comes in contact with a wound (such as a bite or scratch) or mucous membrane (eyes, nose, mouth). Rabies is a reportable disease in humans and animals in Canada.

Ringworm (dermatophytosis):

A fungal skin infection caused by one of several species of Microsporum or Trichophyton. It usually causes no signs in cats, but when it does it can look like almost any feline skin disease.

In humans it can cause distinct areas of red, raised, itchy skin with pale centers, which therefore look like “rings.” The fungus is transmitted by contact with the skin, fur or dander of an infected cat, particularly if the person’s skin is damaged or moist.

Toxoplasmosis:

An infection caused by the protozoal parasite Toxoplasma gondii. Exposure to this is common in people and in cats, but clinical disease is uncommon in healthy individuals.

Infection in pregnant women, however, can cause abortion, premature delivery or still birth. Cats shed oocysts (parasite “eggs”) in their stool that become infective after about 24 hours, but many people are more likely to be exposed to oocysts in soil or by eating undercooked meat. Transmission from cats is likely comparatively uncommon.

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