Definition

A life-threatening but curable infection that causes an eruption of purple lesions on or under the skin that resemble Kaposi's sarcoma. The infection, which occurs almost exclusively in patients with AIDS, can be a complication of cat-scratch disease.

  Description

Bacillary angiomatosis is a re-emerging bacterial infection that is identical or closely related to one which commonly afflicted thousands of soldiers during World War I. Today, the disease, caused by two versions of the same bacteria, is linked to homeless AIDS patients and to those afflicted with cat-scratch disease.

The infection is rarely seen today in patients who don't have HIV. According to the U.S. Centers for Disease Control and Prevention (CDC), an HIV patient diagnosed with bacillary angiomatosis is considered to have progressed to full-blown AIDS.

  Causes and symptoms

Scientists have recently isolated two varieties of the Bartonella bacteria as the cause of bacillary angiomatosis: Bartonella (formerly Rochalimaea quintana) and B. henselae (cause of cat-scratch disease).

B. quintana infection is known popularly as trench fever, and is the infection associated with body lice that sickened European troops during World War I. Lice carry the bacteria, and can transmit the infection to humans. The incidence of trench fever was believed to have faded away with the end of World War I. It was not diagnosed in the United States until 1992, when 10 cases were reported among homeless Seattle men.

The related bacteria B. henselae was first identified several years ago as the cause of cat-scratch fever. It also can lead to bacillary angiomatosis in AIDS patients. Bacillary angiomatosis caused by this bacteria is transmitted to AIDS patients from cat fleas.

These two different types of bacteria both cause bacillary angiomatosis, a disease which is characterized by wildly proliferating blood vessels that form tumor-like masses in the skin and organs. The nodules that appear in bacillary angiomatosis are firm and don't turn white when pressed. The lesions can occur anywhere on the body, in numbers ranging from one to 100. They are rarely found on palms of the hands, soles of the feet, or in the mouth. As the number of lesions increase, the patient may develop a high fever, sweats, chills, poor appetite, vomiting, and weight loss. If untreated, the infection may be fatal.

In addition to the basic disease process, the two different types of bacteria cause some slightly different symptoms. Patients infected with B. henselae also experience blood-filled cysts within the liver and abnormal liver function, whereas B. quintana patients may have tumor growths in the bone.

  Diagnosis

This life-threatening but curable infection is often misdiagnosed, because it may be mistaken for other conditions (such as Kaposi's sarcoma). A blood test developed in 1992 by the CDC detects antibodies to the bacteria. It can be confirmed by reviewing symptoms, history and negative tests for other diseases that cause swollen lymph glands. It isn't necessary to biopsy a small sample of the lymph node unless there is a question of cancer of the lymph node or some other disease.

  Treatment

Recent research indicates that antibiotics used to treat other HIV opportunistic infections can both prevent and treat bacillary angiomatosis. Treatment is usually given until the lesions disappear, which typically takes three or four weeks. A severely affected lymph node or blister may have to be drained, and a heating pad may help swollen, tender lymph glands. Acetaminophen (Tylenol) may relieve pain, aches, and fever over 101°F (38.3°C).

  Prognosis

In most cases, prompt antibiotic treatment in patients with AIDS cured the infection caused by either variety of the bacteria, and patients may resume normal life. Early diagnosis is crucial to a cure.

  Prevention

Studies suggest that antibiotics may prevent the disease. Patients also should be sure to treat cats for fleas.

   Key Terms:

Cat-scratch disease An infectious disease caused by bacteria transmitted by the common cat flea that causes a self-limiting, mild infection in healthy people. Kaposi's sarcoma A malignant condition that begins as soft brown or purple lesions on the skin that occurs most often in men with AIDS.

   Resources:

Periodicals

• Koehler, J. E. "Zoonoses: Cats, Fleas and Bacteria." Journal of the American Medical Association 271 (1994): 531-535.
• Tsang, W. Y., and J. K. Chan. "Bacillary Angiomatosis: A "New" Disease With a Broadening Clinicopathologic Spectrum." Histology and Histopathology 7 (Jan. 1992): 143-52.