Carrión’s disease is an infectious disease caused by a microorganism of the genus Bartonella. Two species have been described, the bacilliformis type and the verrugiformis type. These bacteria are parasites of human red blood and histiocytic cells. The bacilliformis type produces two stages of the disease, a febrile acute hemolytic anemia known as “Oroya fever,” followed by a granulomatous mucocutaneous eruption known as “Verruga Peruana.” The verrugiformis type produces only the verrucose stage.

Etiology and Epidemiology

B.bacilliformis are pleomorphic bacteria, well stained with the Romanovsky stain. In the red blood cells and in the histiocytic cells, the bartonella assumes a rodlike (bacillus) or coccoid shape, 1 to 3 microns in size (Figure VIII.22.1). The electron microscope shows the flagella of the bartonella. It grows well in liquid and in semisolid blood media. The human bartonella is closely related to the nimal bacteria Hemobartonella, Eperythrozoon, and Grahamella.

In 1913 Charles Townsend identified the sandfly Phlebotomus verrucarum as the insect vector of the disease. The female is the only transmitter, and the transmission occurs during the night. Carrión’s disease is a rural disease, and, like yellow fever, it does not need a human reservoir because the bartonella lives in the small animals in the area.

Immunology (Experimental Transmission) Between 1948 and 1950, the author and collaborators conducted a series of experimental transmission on human volunteers. Thirty healthy men were inoculated with parasitic blood through subcutaneous, intramuscular, and intravenous routes. None of the volunteers developed the disease, and the blood culture remained negative after more than 120 days.