Bartonellosis is the current medical name for the condition that has long been known as cat scratch fever. Almost all information on this disease is very new – including the identification of the causative organism. The causative organism was not discovered until 1992 and it was during this current century that the method of transmission was finally discerned. However, now that the bacterium has been identified, a PCR assay (a type of lab test) has discovered the Bartonella organism in 800 year old cat teeth from France. The Bartonella genus includes twenty different species of which eight are zoonotic (can infect humans). Cats seem to be relatively resistant to developing active disease although the organism is harbored in the blood stream of up to 40% of normal cats.
The bacteria are transmitted from cat to cat mainly by the flea and from dog to dog mainly by the tick. Cats do not transfer the bacteria from cat to cat by fighting, mating, grooming, or in-utero. Humans become infected when flea feces from a carrier cat are inoculated into a cat scratch or bite. The Bartonella organism lives within the cat’s red blood cells. When fleas bite, they get a blood meal from the infected cat. This blood meal then puts the bacterium in the flea’s digestive tract. Subsequently, the flea defecates the digested blood and the Bartonella organism onto the cat’s hair and skin. Then, because of their natural grooming habits, cats often have teeth and claws contaminated with flea feces and the Bartonella organism. Human exposure occurs when these contaminated claws and teeth break the human’s skin. Most human beings exposed to the Bartonella organism will not develop active, clinical cat scratch fever.
The Communicable Disease Center estimates that there are approximately 24,000 cases of bartonellosis (cat scratch fever) in humans per year. It appears as though up to 15% of the population of the United States are seropositive to Bartonella; that is, 15% of the American population have been exposed to the Bartonella organism through a cat bite or cat scratch although most of them never had clinically recognizable cat scratch fever or the clinical signs were so mild that they passed unnoticed by the patient. However, another study showed that up to 50% of veterinarians and veterinary technicians that have practiced for more than ten years are seropositive even though most of those professionals also report that they never had clinical cat scratch fever.
Clinical signs of bartonellosis rarely occur in the cat. Bartonellosis is thought to be associated with some of the chronic oral and gingival infections in cats although this could be a casual occurrence rather than cause and effect. Clinical signs of the disease in dogs seems to be associated with heart disease or general lethargy. In humans, cat scratch fever manifests itself as a rash or a pustule or an ulcer in the area of the scratch which develops 3-5 days following the scratch. There can be an associated fever that ranges from minimal to significant. There can also be enlargement of regional lymph nodes. All these clinical signs usually resolve within 4-8 weeks. On rare occasions, the disease can progress to a systemic condition that includes muscle weakness, shortness of breath, constant muscle pain and discomfort, and possibly liver and heart problems. The inflammation and extreme soreness that immediately occurs following a cat scratch or cat bite is not cat scratch fever.
There are several tests available to determine which cats are carrying the Bartonella bacteria but none of them are 100 % reliable. It appears as though fleas are the real problem. The best way to acquire a cat that is not a carrier is to get a kitten from an environment that has scrupulous flea control. Remember, the queen cat cannot give the bacteria to her kitten in any manner except through fleas. Also, be advised that cat scratch fever is a relatively uncommon disease in people that are not immunocompromised (taking steroids, chemotherapy, or have any of the lupus like diseases). Even if your cat is a carrier of the bacteria, the bacteria will not get to you except by flea feces. THEREFORE, ABSOLUTE FLEA CONTROL IS THE NAME OF THE GAME IF YOU ARE CONCERNED ABOUT PREVENTING BARTONELLOSIS.