• Bartonellosis (also known as Bartonella infection) is a bacterial disease that can infect many different species, including cats and humans. People with weakened immune systems are at increased risk of infection.
  • Bartonella infection may cause chronic inflammatory conditions in cats, such as stomatitis (inflammation of the mouth), gingivitis (inflammation of the gums), and inflammatory bowel disease. Some cats may carry the disease but appear to be completely healthy.
  • Bartonellosis is primarily transmitted to cats by fleas. It can be transmitted to humans from cats through a scratch or bite. The disease is rarely transmitted to humans by fleas.
  • Treatment of bartonellosis includes administration of antibiotics and other medications, as necessary, to manage inflammation and pain.
  • Regular application of flea and tick preventives, as recommended by your veterinarian, is important for helping prevent the spread of bartonellosis.

What Is Bartonellosis?

Bartonellosis is a disease caused by several bacteria of the Bartonella family. Bartonella organisms can cause bacterial infection in many species, including humans. Certain strains of Bartonella are known to infect cats. Bartonella organisms can be transmitted from a cat to a human via a bite or scratch, so bartonellosis in humans is commonly called cat-scratch disease.

Cats can become infected with Bartonella through exposure to infected fleas. For this reason, cats that roam outdoors are at greater risk for exposure. There is some evidence that ticks may also transmit the disease.

Some reports state that 12% to 50% or more of cats have been infected with Bartonella. The risk of exposure varies greatly depending on the region of the United States. Areas with warmer climates have a higher incidence of fleas and, therefore, a higher percentage of cats infected with Bartonella.

Signs of Bartonellosis

Many cats that have been exposed to Bartonella do not get sick and, therefore, do not show clinical signs of disease. However, these cats may still transmit the disease to humans. Clinically affected (sick) cats may have various clinical signs, including chronic inflammatory conditions that affect the eyes, mouth, respiratory tract, gastrointestinal system, and even the heart. More specific clinical signs may include:

  • Uveitis (inflammation of a part of the eye)
  • Stomatitis (inflammation of the mouth)
  • Gingivitis (inflammation of the gums)
  • Chronic upper respiratory disease (sneezing, nasal and eye discharge)
  • Inflammatory bowel disease (chronic vomiting and/or diarrhea)
  • Fever

Infected cats may show one or more of the signs listed above. It is very important to discuss these illnesses with your veterinarian because other diseases may also cause these signs.

Symptoms of bartonellosis in humans generally occur about 3 weeks after a cat scratch or bite and include fever and swollen lymph nodes along with a number of other possible symptoms. Consult with your physician regarding any concerns or questions about Bartonella infection.

Diagnosis and Treatment

Your veterinarian may perform a blood test on your cat to check for Bartonella infection. The test indicates the presence of antibodies, which the body uses to fight specific infections. A positive test result means that your cat has been exposed to Bartonella. If your cat is showing signs of disease and has a positive test result, your veterinarian may recommend antibiotics to treat the disease. There is controversy about whether to treat cats that test positive for Bartonella but are not showing signs of illness. It is best to discuss treatment options with your veterinarian.


Regular application of flea and tick preventives, as recommended by your veterinarian, will help to prevent Bartonella infection.

To reduce risk of human infection from cats, keep your cat’s nails trimmed and do not tease or entice play that may result in a bite or scratch from your cat. If you have difficulty trimming your cat’s nails, take him or her to your veterinarian or a professional groomer for nail trimming.