Dr. Dan Meakin
By Dr. Dan Meakin

Ted Nugent made cat scratch fever (actually called cat scratch disease) nearly a household name with his song in the late seventies, but most people still know little about this infection other than it involves a fever spread by cat scratches. In fact, it involves infection by a bacterium called Bartonella henselae, which is spread by fleas.

Classically, cats transmit the organism when they are parasitized by fleas, scratch themselves, and get infected flea dirt (digested host’s blood excreted by fleas) in their claws, and scratch a person or another cat with their dirty claws. 

The Human Disease 

Infection with Bartonella henselae in the immunocompetent (healthy) person leads to cat scratch disease. The inoculation site (a scratch from a claw containing bits of flea dirt) develops a small red bump called a papule. About 2 to 3 weeks following contact with the infected cat, the lymph node in the area of the contact will swell and become painful and a fever develops. These signs generally resolve on their own and the condition is minor. 

If the patient does not have a competent immune system (HIV positive, pregnant), one of several much more serious syndromes can result. The infection goes deeper into the body causing spleen enlargement, and potentially encephalitis, heart valve infection, and other conditions.

Prevention of Human Infection: Guidelines from the Centers For Disease Control 

Prevention of Exposure 

HIV-infected persons, particularly those who are severely immunosuppressed, are at unusually high risk for developing relatively severe disease due to infection with Bartonella, which can be transmitted from cats. These persons should consider the potential risks of cat ownership. Persons who acquire a cat should adopt or purchase an animal aged greater than 1 year that is in good health.    

Although declawing is not generally advised, HIV-infected persons should avoid rough play with cats and situations in which scratches are likely. Any cat-associated wound should be washed promptly. Cats should not be allowed to lick open wounds or cuts of HIV-infected persons. 

How likely is it for a Cat to be Infected? Since fleas carry the bacteria, cats with insufficient flea control are at highest risk. This means cats living in climates that are warm and humid (conditions fleas thrive best in) are most likely to be infected. If conditions are right, up to 40% of cats in an area may be infected. If a person is diagnosed with cat scratch disease, there is a 90% chance that the cats they own will be found infected as well. This sounds somewhat concerning for the cat-owners in a flea area but it is important to realize that an infected cat cannot transmit the infection without a claw full of flea dirt. If the fleas are removed from the infected cat, there will be no flea dirt in the coat and no risk of disease transmission. 

Several illnesses seem to have been associated with Bartonella infection (fever, deep eye inflammation, lymph node enlargement, muscle pain, reproductive failure, and bacterial heart valve deposits called endocarditis.)  

Bartonella henselae infection may be one of main causes of the progressive oral disease of cats called plasma cell stomatitis. It seems that cats infected with both Bartonella henselae and the feline immunodeficiency virus have an increased incidence of this condition compared to what would be expected from either infection alone. 

Bartonella infection may be at the root of numerous chronic inflammatory conditions of cats. With such regionally high numbers of infected cats (up to 40%), it is difficult to prove one way or the other whether there is a real association or just coincidence. 

Is my Cat Infected? 

Any cat who is exposed to fleas or who has either respiratory or oral problems could be infected.

A veterinarian can easily test for it and treatment is available to infected pets. If you suspect that your pet has cat scratch disease, please call us at 513-797-PETS to schedule a test.

Proper care for cats should always include flea prevention to reduce the risk of this and other diseases.