Zoonotic Diseases & Cats

A zoonotic disease is a disease that can be passed from animals to humans. Following are some 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.

Influenza (including H1N1 and H5N1)

While the highly-pathogenic H5N1 strain of avian influenza has yet to be discovered in the US, it is expected to be found here in the future. H5N1 has been isolated from fatal infections of leopards and tigers in Thai zoos after they consumed infected birds. H5N1 has been isolated from a domestic cat and has been experimentally transmitted in laboratory cats. Keeping pets inside when possible and keeping an eye on what they might be consuming outside is their best protection.

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 five cases of plague in humans in Oregon since 1995. Most recently, a Crook County man contracted the plague from a stray cat or mouse (that the cat had in its mouth). A domestic cat in Crook County tested positive for bubonic plague in 2011.

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. According to the law, cats that bite humans should be quarantined for 10 days. Nationally, twice as many cats as dogs are reported to have rabies each year, which is why it’s important to vaccinate your cats for rabies. Multnomah County requires all cats to be vaccinated for rabies. Cats are natural predators and may be attracted to bats, which could be rabid. Oregon law requires unvaccinated pets that may have been in contact with rabid animals (such as bats) to be quarantined for six months or euthanized.


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 and feeding areas.
  • 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.

More tips from the FDA

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.


Approximately 30 to 40% of the world's adults have been infected with the parasite Toxoplasma gondii. Cats can shed the parasite in their feces; however, the cysts do not become infectious for 1 - 5 days after being passed, which is why daily cat box cleaning is recommended. Common everyday contact with a cat is not a risk factor.

This zoonosis can be of concern to pregnant women as it can cause birth defects or miscarriage. If you are pregnant or plan to become pregnant, have another person clean out the litter box every day and try to keep your cats indoors so they cannot eat infected rodents. Wash your hands thoroughly after contact with cat waste and after gardening, as the parasite can be deposited in the soil. Avoid undercooked meat, as it can harbor the parasite, and do not feed undercooked meat to your cat.

Eating raw or undercooked meat containing the parasite is the most common way humans contract toxoplasmosis. Most people who get toxoplasmosis do not get sick, but some people will get swollen glands, muscle aches, and feel as though they have the "flu."


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.

Take your cat to your veterinarian for regular check-ups (at least once per year), and if your cat exhibits any of the symptoms of these diseases. In the vast majority of cases, these diseases are treatable.

Updated: 2012-06-15 07:00:00

Author: Oregon Veterinary Medical Association