Bacillary angiomatosis

Bacillary angiomatosis (BA) is a bacterial infection caused by either Bartonella henselae or Bartonella quintana. Bartonella henselae is most often transmitted through a cat scratch or bite, though ticks and fleas may also act as a vector. On the other hand, Bartonella quintana is usually transmitted by lice.

BA is characterised by the proliferation of blood vessels, resulting in them forming tumour-like masses in the skin and other organs. It most commonly manifests in people with AIDS, rarely appearing in those who are immunocompetent. While curable, it is potentially fatal if not treated.

Symptoms
Cutaneous BA is characterised by the presence of lesions on or under the skin. Appearing in numbers from one to hundreds, these lesions may take several forms:


 * papules or nodules which are red, globular and non-blanching, with a vascular appearance
 * purplish nodules sufficiently similar to Kaposi's sarcoma that a biopsy may be required to verify which of the two it is
 * a purplish lichenoid plaque
 * a subcutaneous nodule which may have ulceration, similar to a bacterial abscess

While cutaneous BA is the most common form of BA, BA can also affect several other parts of the body, such as the brain, bone, bone marrow, lymph nodes, gastrointestinal tract, respiratory tract, spleen and liver. Symptoms vary depending on which parts of the body are affected; for example, those whose livers are affected may have an enlarged liver and fever, while those with osseous BA will experience intense pain in the affected area.

Treatment and prevention
BA responds dramatically to several antibiotics. Usually, erythromycin will cause the skin lesions to gradually fade away in the next four weeks, resulting in complete recovery. Doxycycline may also be used. However, if the infection does not respond to either of these, the medication is usually changed to tetracycline. If the infection is serious, then a bactericidal medication may be coupled with the antibiotics.

If a cat is carrying Bartonella henselae, then it may not exhibit any symptoms. Cats may be bacteremic for weeks to years, but infection is more common in young cats. Transmission to humans is thought to occur via flea feces inoculated into a cat scratch or bite, and transmission between cats occurs only in the presence of fleas. Therefore, elimination and control of fleas in the cat's environment are key to prevention of infection in both cats and humans.