Bartonellosis, also known as
Cat Scratch Disease or
Cat Scratch Fever, is an infectious disease of humans. Evidence is increasing that perhaps the cat becomes infected with the causative organism, but it does not appear to produce any disease in the cat. Very little is known or understood about the role of the cat as a reservoir for this disease.
What are the risk 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 its apparent seasonality remains unknown.
What are the clinical signs?
Antibodies are proteins which are produced by the immune system in response to some 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. Very few of those testing positive have actually had the disease. The majority have had inapparent infections or have been exposed to the CSD organism without any disease occurring.
This is generally a mild disease in humans. Many people experience fever, chills, and lethargy which last only a few days. Unless the skin test is performed or the organism is cultured, it may be diagnosed as influenza. However, the more severe forms of the disease will 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.
Is the cause known?
The cause of CSD has recently been identified as a bacterium called
Bartonella henselae. A cat scratch is not necessary to transmit the organism;
contact alone is sufficient.
The role of fleas and ticks in the life cycle and transmission of the organism is an area of research interest at present.
How is it diagnosed?
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.
What is the 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.
What is the prognosis?
The disease is usually self-limiting. It runs a course of several days to several weeks and then subsides.
Can it be transmitted to me or my family?
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.
How is it prevented?
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.
- Always contact a physician whenever an immune-deficient person receives any animal scratch or bite.
