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Zoonotic Diseases & Cats

Zoonotic Diseases & Cats

A zoonotic disease is a disease that can be passed from animals to humans. These diseases can be caused by viruses, bacteria, parasites, and fungi. Humans can contract zoonotic or vector-borne diseases through contact with an animal, its bodily fluids, its infected waste or its living environment; by contact with water or soil contaminated by infected animal waste; by eating meat from infected animals or eating food such as fruits and vegetables that have been contaminated by infected animal waste; or through vectors—such from infected animals to humans via mosquitoes, fleas or ticks. Following are some zoonoses related to cats:

Cat Scratch Disease

Cat scratch disease (CSD) is a bacterial disease caused by Bartonella henselae. Approximately 90% of CSD patients have a history of cat contact. Symptoms include: swollen lymph nodes, especially those around the head, neck, and upper limbs; fever; headache; fatigue; and a poor appetite. Kittens are more likely to be infected and to pass the bacterium to people. About 40% of cats carry the bacteria at some point in their lives although they do not show any signs of the illness, so you cannot tell which cats may spread the disease.

To prevent CSD, avoid "rough play" with cats, especially kittens; this includes any activity that may lead to cat scratches and bites. Wash cat bites and scratches immediately and thoroughly with soap and water. Do not allow cats to lick open wounds. Contact your physician right away if you develop pronounced swelling and an infection with pus where you were scratched or bitten by a cat.

Methicillin-Resistant Staphylococcus Aureus (MRSA)

Transmission of MRSA infections between pets and humans are increasing, with the most common being infections of the skin, soft-tissue and surgical infections. Dog or cat bites can result in infection, caused by bacteria from the animal's mouth and on the patients' body. Animals are potential reservoirs of MSRA infection due to increasing prevalence of community-acquired MRSA (CA-MRSA) in humans and domestic animals such as dogs, cats and horses. MRSA-associated infections in pets are typically acquired from their owners and can potentially cycle between pets and their human acquaintances.

Treatment of MRSA infections in pets is similar to that used in humans. Resistant to penicillin and methicillin, CA-MRSA infections can still be treated with other common-use antibiotics. CA-MRSA most often enters the body through a cut or scrape and appears in the form of a skin or soft tissue infection, such as a boil or abscess. The involved site is red, swollen, and painful and is often mistaken for a spider bite.

Though rare, CA-MRSA can develop into more serious invasive infections, such as bloodstream infections or pneumonia, leading to a variety of other symptoms including shortness of breath, fever, chills, and death. CA-MRSA can be particularly dangerous in children because their immune systems are not fully developed. You should pay attention to minor skin problems—pimples, insect bites, cuts, and scrapes—especially in children. If the wound appears to be infected, see a healthcare provider.


While rare, there have been cases of plague in humans in Oregon. A cat in Crook County tested positive in 2011. And, in 2012, a Crook County man contracted the plague from a stray cat or mouse (that the cat had in its mouth).

Plague can be passed from fleas feeding on infected wild mammals to pets such as cats and to their human owners. People can protect themselves, their family members and their pets by using flea treatments on your pets to prevent them from bringing fleas into your home.

Symptoms of plague typically develop within one to four days after exposure and include fever, chills, headache, weakness and a bloody or watery cough due to infection. Three clinical syndromes have been described: bubonic (lymph node infection), septicemic (blood infection), and pneumonic (lung infection). Bubonic plague is the most common form and is characterized by high temperatures, lethargy and swollen lymph nodes, most commonly in the neck and under the jaw. Infected lymph nodes may spontaneously abscess and drain. 

People should contact their health care provider if plague is suspected and a veterinarian if pets or other animals exhibit symptoms consistent with the plague. Early treatment for pets and people with appropriate antibiotics is essential to curing plague infections. Untreated plague can be fatal for animals and people. Antibiotics to prevent or treat plague should be used only under the direction of a health care provider.


Rabies is an infectious viral disease that affects the nervous system. It is only transmitted by a bite from a rabid animal. If you are bitten by any animal—even a household pet—and especially if the bite is from a wild animal, such as a bat, it is important to consult with your health care provider.

Dogs, cats and ferrets should be vaccinated against rabies. Vaccinating pets not only protects them but it provides a “buffer zone” between humans and rabid wild animals. Oregon law requires all dogs to be vaccinated against rabies as early as three months of age. In addition, Multnomah County requires all cats to be vaccinated for rabies.

Oregon law requires that unvaccinated pets that may have been in contact with rabid animals to be vaccinated and quarantined for 4 months (dogs and cats) or 6 months (ferrets), or euthanized. The contact animal, such as a bat, is considered rabid unless it is tested and is negative.

Vaccinated dogs, cats, and ferrets exposed to a rabid animal should be revaccinated immediately, kept under the owner's control, and quarantined for 45 days. Any illness in an isolated or confined animal should be reported immediately to the local health department. If signs suggestive of rabies develop, the animal should be euthanized and tested.


Ringworm is not a worm, but a fungal disease that can infect a cat's hair, nails, or skin. Ringworm usually makes a bald patch of scaly skin or a ring-shaped rash that is reddish and may be itchy. Cats, especially young cats, can harbor the fungus without any noticeable clinical signs, so preventative care by your veterinarian is important. When diagnosed, ringworm should be treated because the fungus can be transmitted to humans by direct contact with an infected animal's skin, hair, bedding or other items.


Salmonellosis is caused by the bacteria Salmonella. It can cause diarrhea, fever and abdominal cramps 12 to 72 hours after infection. The illness usually lasts four to seven days, and most people recover without treatment, although it can be fatal to those with fragile immune systems. About 40,000 human cases of Salmonella infection are reported in the US each year. Pets with Salmonella infections may be lethargic and have diarrhea or bloody diarrhea, fever, and vomiting. Some pets will have only decreased appetite, fever and abdominal pain. Well animals can be carriers and infect other animals or humans. Scoop your cat's litter box daily and dispose of the stool in a tightly sealed plastic bag. It is possible to contract Samonella from handling contaminated pet food or treats.

To reduce infection risks, you should:

  • Wash hands after contact with pets, pet food and pet bowls. Wash with soap and running water for at least 20 seconds, then rinse and dry your hands with a paper towel.
  • Routinely clean pet food bowls, feeding areas, litter boxes and habitats.
  • Keep children younger than age 5 away from pet food and feeding areas.
  • Clean pets' food and water dishes in a separate sink or tub, not in the kitchen or bathtub.
  • Avoiding bathing infants in the kitchen sink.

Unfortunately, pet food can be contaminated by Salmonella, and recalls of pet food have occurred. Please check our Recalls & Warnings section for the latest information on current recalls.

Toxocariasis (Roundworm)

Adult roundworms are an intestinal parasite that resemble strands of spaghetti. Their eggs are shed through a pet’s feces and, while fresh feces are not infectious, the eggs become infectious over time as they sit in grass, soil or sand. This is why picking up pet waste promptly is important. Roundworms can cause vomiting or diarrhea. Children are more prone to contract roundworm as they are more likely to touch infected dirt or sand and then put their hands into their mouths. Do not let children eat sand or dirt. Children should wash hands thoroughly after playing in areas where pet waste may have been deposited. Keep sandboxes covered when not in use. In rare cases, roundworm infection can cause an eye disease that can lead to blindness; such infections can be more serious in children than adults. Gardeners should wear gloves and wash hands after working outside.


Toxoplasmosis is a disease caused by the parasite Toxoplasma gondii and can be passed to humans through contaminated cat feces. However, the risk of being exposed to the disease by your household cat is very small. It is not necessary to avoid contact with your cat while you are pregnant. You should continue to enjoy your cat's companionship during this time.

You may want to consider being tested for the antibodies to toxoplasmosis prior to becoming pregnant. If you have already been exposed and developed antibodies to the infection, you cannot be reinfected.

It's always best to practice reasonable prevention. With proper precautions, infection can be avoided:

  • It is important to note that it is more common to be exposed to the disease through gardening activities or by eating uncooked or undercooked meat or unwashed vegetables that may harbor the parasite than through contact with your cat or its litter box.
  • Wear gloves while gardening and wash your hands when you are through, as the parasite can be deposited in the soil by infected neighborhood cats to whom you have not had the same level of exposure to as with your own cat.
  • Avoid raw or undercooked meat and do not feed raw or undercooked meat to your cat.
  • Do not using a knife exposed to raw meat on cooked meat.
  • Keep your cat off countertops where food is prepared.
  • Clean the cat box daily and wash your hands thoroughly afterwards. The parasites are not infectious when first passed by cats in their feces. The cysts do not become infectious for 1 - 5 days after being passed. Most cats are fastidious about cleaning and do not leave feces on their fur; therefore, common contact with a cat is not a risk factor.
  • Try to keep your cat indoors (if the cat will accept it), especially if your cat tends to hunt rodents or birds, which is often how cats are exposed to the disease.


  • Regular veterinary care is important for the health of every animal. Because any cat at any age can become infected with parasites, an annual exam with a fecal exam is important. Your veterinarian can recommend a parasite prevention and vaccination protocol for your cat to keep it safe from infectious diseases.
  • One of the best ways to prevent zoonotic diseases is to promptly clean up pet waste. Many parasites or bacteria are not infectious in fresh pet waste, but become infectious over time and can contaminate the soil, sand or grass if allowed to sit. Wash your hands thoroughly with hot, soapy water after playing with your cat or handling its waste.
  • If you have any questions about these diseases or concerns about your pet's health, please consult your veterinarian. If you have concerns about your health, please seek medical attention from your health care provider.

Updated: June 25, 2019