As the sandflies bite, the bacteria are inoculated into the capillaries, where in a variable period of time (around 21 days) it invades the red blood cells producing severe intravascular hemolytic anemia (acute phase of Carrion's disease). This phase is a potentially life-threatening infection, and it is associated with high fever, anemia, and transient immunosuppression. The acute phase typically lasts two to four weeks. Peripheral blood smears show anisomacrocytosis with many coccobacilli adhered to red blood cells. Thrombocytopenia is also seen and can be severe. Neurological involvement is sometimes seen (neurobartonellosis) and the prognosis in this case is poor. The most feared complications are super-infections, mainly by enterobacteria such as Salmonella, or parasites such as Toxoplasma gondii and Pneumocystis. When the bacterium invades endothelial cells, it produces the chronic manifestation of the disease known as verruga peruana. This phase consists of a benign skin eruption with raised, reddish-purple nodules (angiomatous tumours). Visualization of the bacteria is possible using silver stain (the Warthin–Starry method) on biopsies.
Bartonella bacilliformis
Bartonella rochalimae
Cryptosporidium parvum
Prevotella bivia
Yersinia pestis
Salmonella enterica subsp. enterica
Yersinia rohdei
Bartonella henselae