Ron Hines DVM PhD 4/42/06

Cat scratch fever or disease is a bacterial infection of cats and humans caused by a small, fragile (fastidious), intracellular bacteria, Bartonella henselae . It appears that other Bartonella species occasionally cause the disease as well (B. clarridgeiae). These organisms were previously called Rochalimaea. Most people develop this disease after being scratched or bitten by an infected cat. It occasionally affects dogs.

Signs In Humans:
Cat scratch fever was first recognized in people in 1931. Cases occur worldwide. The disease is most frequently associated with the bite or scratch of a kitten under six month of age. Children and young adults 2-24 years of age and veterinarians make up 80-90% of the human cases. Most cases occur in the fall and winter months. People who have been scratched or bitten first develop one or more pustules (pimples) at the site of the wound. One to four weeks later, nearby lymph nodes become swollen and tender. These are usually the lymph nodes at the armpit. Mysteriously, patients with no known exposure to cats will occasionally develop the disease. Fever, headache and fatigue are common. Some people develop a concurrent tonsillitis and neck pain. It is rare for more serious signs to develop in healthy people and most recover without treatment over a three-week period. However, when a person’s health is not good or the immune system that protects the body is compromised, a series of much more serious diseases can occur. The symptoms of this atypical bartonellosis are highly variable and can be fatal. Often these are people who have undergone organ transplants, chemotherapy or have AIDS. One of these unusual forms called bacillary angiomatosis in which blood-filled cysts appear on the skin. A second is called Parinaud’s oculolandular syndrome. When it affects the liver and spleen it is called peliosis hepatitis or splenic peliosis. It sometimes affects the linings of the heart (endocarditis) and other times the eye (retinitis) and optic nerve. It can also affect the lungs and brain.

Signs In Cats:
Most cats that are infected with B. henselae show no disease at all, although the bacteria can be cultivated from their blood for long periods. It is a very common infection in cats – forty percent of all cats contract bartonellosis sometime in their lives and many cats are asymptomatic carriers for long periods of time. Some cats with this disease run a fever for two to three days. These signs are usually missed by their owners. The cat’s lymph nodes may swell and they may become moderately anemic for a few weeks. Sometimes it is a trip to the vets or a minor surgical procedure that precipitates the diseases. It appears that a few cats that contract bartonellosis show mild loss of sensation in their paws, lack of balance and disorientation that resolves within a few days. At the microscopic level, there is evidence that the organism attacks the liver, kidney, spleen and lining of the heart. But damage to these organs is usually temporary and without symptoms.

Recently, an article reported that 58% of cats with uveitis or inflammation of the anterior portion of the eye,51% of cats with conjunctivitis and 86% of cats with chorioretinitis (inflammation of the retina) as well as 75% and 58% respectively of cats with keratitis and corneal ulcers respectively, were positive for Bartonella. This would make Bartonella one of the most common causes of eye inflammation in the United States. This condition responded well to treatment with Doxycycline (5mg/pound twice a day for 6 weeks) azithromycin (5mg/pound once a day for 21 days) or rifampin (5mg/pound once a day for 21 days). When using doxycycline capsules one must follow the capsule administration with a considerable amount of water to keep the capsule from lodging in the esophagus. Azithromycin is the preferred drug for this condition because it is also effective against mycoplasma which may be present. Journal of the American Animal Hospital Association pages 6-12 January/February 2004.

Mode Of Transmission:
The role of various insects such as fleas and ticks in spreading this disease is not fully understood. Experimentally, cat fleas will transmit the disease from one cat to another as will a blood transfusion.

Cats in the warmer and more humid portions of the United States have the highest incidence of Bartonellosis. Prevalence ranges from 30-50% of all cats in warm states to 5-7% in colder states. The high-prevalence areas are the same areas where cat fleas are most common.

Cats are capable of spreading B. henselae infection to people. Kittens and young stray cats spread the disease more commonly than adult, indoor pet do. The majority of cats that spread the disease to humans are not clinically ill. The bacteria can persist in infected cats for at least two years. Some authorities state that cat fleas can spread the disease to people and others state that they can not. We do know that dried “flea dirt” which is digested blood, harbors living bacteria for over nine days. We think that this dirt becomes lodged under the cat’s claws from where it is passed to people through a scratch. We also suspect that ticks can also transfer the disease to humans. Cat bites can also pass along bartonellosis. cat scratch fever bartonella bartonellosis
Tick bites are also known to spread the disease. It is possible that cat urine can also spread the disease. When it affects dogs, it may be transmitted by ticks.

Diagnosis: cat scratch fever bartonella bartonellosis
Diagnosis in people is not straight forward or easy. Most physicians rely on a history of exposure to a cat, typical enlarged painful lymph nodes, fever and the lack of another likely cause. Diseases such as tuberculosis, lymphoma and brucellosis need to be ruled out. A skin test similar to the tuberculosis tine test is available for the disease, as are blood tests for use in cats and humans.

Diagnosis in cats relies upon growing the organism from blood or lymph node or through a test called a polymerase chain reaction.

Treatment:
Although ninety percent of the cases will resolve without treatment with antibiotics, they may take several months to do so. Doxycycline, erythromycin and rifampin are the antibiotics of choice in humans but the course of the disease can also be shortened using azithromycin, ciprofloxacin, trimethoprim/ sulfamethoxazole, or clarithromycin.

In cats, 2-4 week treatment with doxycycline or enrofloxacin alleviates symptoms of the disease. Treated cats are still subject to relapse or carrier states.

Prevention:
Keep your cat indoors. Indoor cats are much less likely to be exposed to Bartonella.

Do not let your children roughhouse with kittens – especially kittens that were recently obtained from an animal shelter or found as strays.

If you or your children are scratched or bitten vigorously and immediately wash the wound out with warm running water and hydrogen peroxide or isopropyl alcohol.

If you have sores or scratches on your hand wear gloves when handling your cat or allowing it to lick you.

Keep your cat’s toenails clipped short and filed. Although it is not one hundred percent effective in reducing contagion, high risk people in fragile health should have their cat declawed on all four feet.

Use one of the newer flea-control products on your cat.

Neuter and spay your cats so they do not roam, fight and stress out.

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