B. bacilliformis is considered the most deadly species to date, with a death rate of up to 90% during the acute phase, which typically lasts two to four weeks.

Neurologic manifestations (neurobartonellosis) are altered mental status, agitation, or even coma, ataxia, spinal meningitis, or paralysis.

[citation needed] The chronic manifestation consists of a benign skin eruption with raised, reddish-purple nodules (angiomatous tumours).

It manifests as gradual regional lymph nodes enlargement (axilla, groin, neck) which may last 2–3 months or longer, and a distal scratch and/or red-brown skin papule (not always seen at the time of the disease).

[citation needed] B. henselae and B. quintana can cause bacillary angiomatosis, a vascular proliferative disease involving mainly the skin, and other organs.

[9] Differential diagnoses include Kaposi's sarcoma, pyogenic granuloma, hemangioma, verruga peruana, and subcutaneous tumors.

[citation needed] B. henselae is the etiologic agent for peliosis hepatis, which is defined as a vascular proliferation of sinusoid hepatic capillaries resulting in blood-filled spaces in the liver in HIV patients and organ transplant recipients.

Classical presentations include a febrile illness of acute onset, headache, dizziness, and shin pain.

Chronic infection manifestations include attacks of fever and aching in some cases and persistent bacteremia in soldiers and homeless people.

Bartonella species also have a tropism for endothelial cells, observed in the chronic phase of Carrion's disease (also known as verruga Peruana) and bacillary angiomatosis.

[citation needed] There are several methods used for diagnosing Bartonella infection including microscopy, serology, and PCR.

[citation needed] ELISA (enzyme-linked immunosorbent assay) is another method that has been used to detect Bartonella, but it has a low sensitivity (17-35%).

[27] It is endemic in some areas of Peru,[28] is caused by infection with the bacterium Bartonella bacilliformis, and transmitted by sandflies of genus Lutzomyia.

[citation needed] Trench fever, produced by Bartonella quintana infection, is transmitted by the human body louse Pediculus humanus corporis.

[31] The disease was named after medical student Daniel Alcides Carrión from Cerro de Pasco, Peru.

Carrión described the disease after being inoculated at his request with the pus of a skin lesion from patient Carmen Paredes in 1885 by Doctor Evaristo M. Chávez, a close friend and coworker in Dos de Mayo National Hospital.

Barton originally identified them as "endoglobular" structures, bacteria living inside red blood cells.

[32] In 1988, English et al. [33] isolated and cultured a bacterium that was named Afipia felis in 1992 after the team at the Armed Forces Institute of Pathology that discovered it.

are commonly treated with antibiotics including azithromycin, based on a single small randomized clinical trial.