The diseases caused by Bartonella species are listed in Table 1. Because B. quintana and B. henselae are more common causes of infections in humans, these agents are addressed in greater depth.
Table1. Organisms Belonging to the Genus Bartonella and Recognized to Cause Disease in Humans*
Trench fever, caused by B. quintana, was largely considered a disease of the past. Clinical manifestations of trench fever range from a mild influenza-like headache and bone pain to splenomegaly (enlarged spleen) and a short-lived maculopapular rash. During the febrile stages of trench fever, infection may persist long after the disappearance of all clinical signs; some patients may have six or more recurrences. B. quintana has reemerged and has been reported in cases of bacteremia, endocarditis, chronic lymphadenopathy, and bacillary angiomatosis primarily in low socioeconomic groups in Europe and the United States, as well as in patients infected with the human immunodeficiency virus (HIV). Bacillary angiomatosis is a vascular proliferative disease involving the skin (other organs such as the liver, spleen, and lymph nodes may also be involved) and occurs in immunocompromised individuals such as organ transplant recipients and HIV-positive individuals. Prolonged bacteremia with B. quintana infections may be associated with the development of endocarditis and bacillary angiomatosis.
B. henselae is associated with bacteremia, endocarditis, and bacillary angiomatosis. Of note, recent observations indicate that B. henselae infections appear to be subclinical and are markedly underreported, as problems with current diagnostic approaches are recognized. In addition, B. henselae causes CSD and peliosis hepatitis. About 24,000 cases of CSD occur annually in the United States; about 80% of these occur in children. The infection begins as a papule or pustule at the primary inoculation site; regional tender lymphadenopathy develops in 1 to 7 weeks. The spectrum of disease ranges from chronic, self-limited adenopathy to a severe systemic illness affecting multiple body organs. Although complications such as a suppurative (draining) lymph node or encephalitis are reported, fatalities are rare. Diagnosis of CSD requires three of the four following criteria:
• History of animal contact plus site of primary inoculation (e.g., a scratch)
• Negative laboratory studies for other causes of lymphadenopathy
• Characteristic histopathology of the lesion • A positive skin test using antigen prepared from heat treated pus collected from another patient’s lesion
Bartonella clarridgeiae is a newly described species capable of causing CSD and bacteremia.
Peliosis hepatitis caused by B. henselae may occur independently or in conjunction with cutaneous bacillary angiomatosis or bacteremia. Patients with peliosis hepatitis demonstrate gastrointestinal symptoms. Symptoms include fever, chills, and an enlarged liver and spleen that contain blood filled cavities. This systemic disease develops in patients infected with HIV and other immunocompromised individuals.
