CARRION'S DISEASE

Bartonellosis or Carrion’s disease is caused by Bartonella bacilliformis, a small gram negative cocobacillus that infects RBCs. It was named after Dr. A.L Barton, who described its association with this disease. As a medical student, Daniel Carri�n had injected himself in 1885 with blood from the skin lesion of a patient who had verruga peruana and he subsequently developed Oroya fever. The disease is geographically restricted to region of western Andes such as Peru, Bolivia, Chile, Guatemala, Ecuador, and Columbia.

Transmission & clinical types: This insect borne disease is spread by the bite of its vector, the sandfly (Lutzomyia verrucarum). This vector often bites during the night. Carrion’s disease is biphasic in nature; the first phase is known as Oryoya fever and the second phase is known as Verruga peruana.

Oroya fever: Bacteremia of Oroya fever begins 3-12 weeks after a bite from an infected sand fly. Oroya fever is severe in manifestation and is characterized by high fever, lymphadenopathy, hepatosplenomegaly, and hemolytic anemia as this bacterium can infect more than 90% of RBCs at this stage. After invading RBCs the organism replicates in vacuoles. It also secretes an endothelial cell’stimulating factor that causes proliferation of both endothelial cells and blood vessels. If untreated, mortality may be 40-90%. Survivors may be more susceptible to salmonellosis or toxoplasmosis during the convalescent period. Survivors may also develop persistent bacteremia. Persistently infected humans are the main reservoir of B. bacilliformis.

Verruga peruana: It is the second phase of the disease, and is also known as Peruvian wart. Lesions develop in untreated survivors as crops that begin weeks to months later. During this stage the bacteria are absent in the blood but multiple disfiguring skin eruptions occur, which are characterized by vascular endothelial proliferation. Various stages of small to larger nodules, mulaire lesions, and fibrosis may occur simultaneously. These tumor-like proliferations may persist for a year but this condition is not fatal. Verruga peruana can also occur in patients without Oroya fever.

Laboratory diagnosis: Oroya fever is diagnosed by demonstration of bacilli in blood smears stained by Giemsa or Wright stain. Both thick and thin smears must be made. They appear as red, pleomorphic, rod shaped � slightly curved organisms that measure 1-3 �m x 05-0.75 �m. Bacteria are often found attached to or inside erythrocytes. In biopsy specimens stained by Giemsa, they appear inside endothelial cells. It can be cultured on brain hear infusion agar with 5% blood and incubated at 25^oC. The organism is oxidase negative, catalase positive, and motile. Direct detection of the organisms or their nucleic acids is a viable option if fresh or frozen tissue or blood is available.

Treatment: Choloramphenicol is the drug of choice. Penicillin, tetracycline or streptomycin may also be used. Antibiotic susceptibility is not routinely tested in patients with bartonellosis because susceptibility studies may fail to predict response to therapy.