Contributing Factors

A cat scratch is sometimes, but not always, associated with this disease. In one study, 99% of patients with CSD had exposure to cats. An increased risk of transmission is present when a kitten is involved as opposed to adult cats.

Most cases are reported in the fall and winter, but the reason for this apparent seasonality remains unknown.

Clinical Signs

This is generally a mild disease in humans. Many people experience only fever, chills, and lethargy that last a few days. Unless a skin test is performed or the organism is cultured, it may be diagnosed as influenza.

Severe forms of the disease produce very high fevers, marked lethargy, anorexia, and swollen lymph nodes, usually in the axillae (armpit) or groin. The lymph nodes may enlarge to the point of rupturing, or they may need to be opened surgically to establish drainage and relieve pain.

Antibodies are proteins which are produced by the immune system in response to certain stimulus. About 5% of the United States population is known to have antibodies to CSD. Interestingly, about 20% of U.S. veterinarians will test positive for CSD antibodies while very few have actually had the disease. The majority have had inapparent infections or have been exposed to the CSD organism without any symptoms of the disease.

Cause

The cause of CSD has recently been identified as a bacterium called Bartonella henselea. A cat scratch is not necessary to transmit the organism; contact alone is sufficient.

Researchers are currently investigating the role of fleas and ticks in the life cycle and transmission of the organism.

Diagnosis

The organism does not appear to cause disease in the cat. When humans are infected, the physician may make a diagnosis based upon clinical signs, exposure to cats, blood tests, and studies of lymph node biopsies.

Treatment

The appropriate course of therapy will be prescribed by your physician. In many cases, the disease is self-limiting and requires little or no treatment. In others, antibiotics, pain medication, and bed rest may be indicated.

Prognosis

Again, the disease is usually self-limiting: it runs a course of several days to several weeks and then subsides. Even the severe forms respond to treatment within a few days, although complete recovery may take several weeks.

Transmission to Humans

The cat is involved because many cases of CSD are preceded by a cat scratch. Our best understanding of the cat's involvement is as follows:

The cat is almost always a kitten; adults are rarely involved.

The cat appears to be contagious for only about 2-3 weeks.

Declawing does not appear to decrease the transmission. The organism lives in the cat's mouth and can be transmitted to the paws by grooming.

One should be very concerned about a family member having CSD. However, indefinitely banning cats from one's household is generally not warranted. It has been shown that less than 10% of family members scratched by the same cat develop the disease. In addition, there has not been a person recorded as having had the disease twice.

Prevention

At present, there is no available test to determine which cats carry the CSD organism. General considerations are as follows:

Declawing is not generally considered useful since the organism may be transmitted by contact alone.

When a kitten is involved, the likelihood of spreading the organism decreases as the kitten matures.

Euthanasia is not indicated because the involved cat is usually healthy.

If a cat does scratch or bite, wash the wound thoroughly with soap and water and, if indicated, contact a physician.

When an immunodeficient person receives any animal scratch or bite, always contact a physician.