Most people have heard of “cat scratch fever” –– or at least they’ve heard the Ted Nugent song. But few know how the disease affects cats and, potentially, their people. The infection, officially called bartonellosis and caused by a bacteria carried by fleas, can bring on a host of symptoms in cats –– fever, sneezing, eye inflammation –– or none at all. And it can be transmitted to humans through a scratch or bite.


Bartonellosis is caused by several bacteria of the Bartonella family. Bartonella organisms can infect many species, including humans and cats. The specific organism transmitted from cats to humans via bites or scratches is called Bartonella henselae. This version of bartonellosis in humans is commonly called “cat scratch disease” or “cat scratch fever.”

Cats usually become infected with Bartonella after exposure to infected fleas. For this reason, outdoor kitties –– especially those that roam freely and don’t receive regular flea preventives –– are at greater risk for the disease. This doesn’t mean, however, that indoor cats are immune.

Some reports state that Bartonella has infected 12 percent to 50 percent or more of cats, but 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 the disease.

Bartonellosis in humans generally occurs after a cat scratch or bite. About 20,000 humans in the US are reportedly sickened every year by this infection. The disease causes fever and swollen lymph nodes along with a number of other possible symptoms.

Signs and Identification

Plenty of cats that have been exposed to Bartonella don’t get sick and, therefore, don’t show clinical signs of the disease. Nonetheless, these cats may still transmit the disease to humans.

Sick cats may display a variety of 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 –– or none of the above.

Diagnosing bartonellosis can be as simple as testing a blood sample for the presence of antibodies. A positive test result means the cat has been exposed to Bartonella, but that doesn’t necessarily mean he or she is currently ill or that treatment is required. That’s where the complexity (and frustration) lies in diagnosing this disease.

Affected Breeds

This disease has no breed predilection.


Antibiotics are typically indicated for cats that test positive for the disease and show symptoms of it. If a cat is not showing symptoms yet tests positive on a screening, antibiotics are considered controversial. But because bartonellosis is a disease that’s transmissible to humans, some veterinarians will initiate antibiotic therapy, especially if members of the household are very young, very old, pregnant, or otherwise immunologically challenged.


Regular application of flea and tick preventives, as recommended by most veterinarians, will help 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. Children should be taught to play gently with cats and avoid petting stray cats.

This article has been reviewed by a Veterinarian.