Overview

Most commonly known as “cat scratch fever,” the disease one can get following a cat scratch is in fact an infection caused by the bacterium Bartonella henselae. The bacterium parasitizes fleas, so generally speaking a cat is much more likely to be a carrier of cat scratch disease if it has a flea problem. Dogs may also be infected by this bacterium; however, in both dogs and cats there are generally no symptoms, and it is believed that the bacterium does not influence the animals’ long term health. When humans contract the bacterium, the resulted infection is generally benign and usually can resolve by itself. However, in patients with weak immune systems, it is a much more serious condition and complications can occur.

Since the bacterium causing this disease is flea-borne, careful flea control is the most effective way to prevent contracting and spreading cat scratch disease. The disease is not transmittable amongst cats in the absence of fleas. People who are at higher risk, including young children and immunosuppressed patients, should avoid rough play and other situations where cat scratches are likely. Any wounds caused by cats should be disinfected promptly.

Symptoms and Diagnosis

In a normal, healthy person cat scratch disease is usually relatively mild. The scratched or bitten site develops small, red bumps (papules), and the patient will later develop swollen, painful lymph nodes, muscle aches, fatigue, and slight fever. Symptoms may appear as late as two months after contact with cats. In patients with weakened immune systems the infection can spread and create serious complications, including heart valve infection, and enlarged spleen. Immuno-competent patients sometime can develop more serious infections, although this is very rare. Most cases will resolve spontaneously, sometimes without treatment. The disease is most commonly found in children, because their immune systems are not yet fully developed.

Diagnostic criteria for this disease include symptoms, the history of contact with cats, and a skin reaction test. It is also possible to test the cat for the presence of the bacterium in its blood, however the tests can be time consuming and not entirely reliable.

Treatment

Infected humans can be given antibiotics such as ciprofloxacin and doxycycline. As the disease is benign and the symptoms are generally self-limiting, sometimes treatment is not necessary for patients with no other complications. However, since the symptoms can sometimes persist for weeks or even months, medication can be given to accelerate the recovery process.

Around 40% cats carry Bartonella bacteria at some point in their lives, and they do not usually show any symptoms; however, it is possible to treat infected cats with antibiotics. Kittens are more likely to be carriers of the bacterium than adult cats.