An acute infectious disease caused by Bartonella quintana or B. henselae. It is characterized by skin lesions that may vary from small papules to pyogenic granulomas or pedunculated masses. These occur anywhere on the skin and may involve mucous membranes. If the lesions ulcerate, they can extend to and destroy underlying bone. In addition, the organisms are disseminated to the fiver, spleen, bone marrow, and lymph nodes. In the fiver there may be painful, multiple, cystic, blood-filled spaces (peliosis hepatitis). Most patients with this disease are immunocompromised or infected with human immunodeficiency virus (HIV). In the untreated immunocompetent patient, recovery may be prolonged but is usually complete. In the untreated immunocompromised patient, death is the likely outcome. When the organisms are disseminated, treatment for several months with oral doxycycline or oral erythromycin will be of benefit in altering the course of the disease. Culture of the organism provides diagnosis.