Bartonella bacilliformis anemia (Oroya fever) is a febrile hemolytic anemia with distinguishing clinical and hematologic characteristics. It occurs as an infrequent clinical form during the invasive stage. The onset is variable with or without chills, followed by a moderate temperature which does not parallel the intensity of the anemia. Hemorrhages, petechial spots, epistaxis may occur and are due to thrombocytopenia. Clouding of the sensorium and delirium are rather uncommon. There is a generalized lymphadenopathy but no splenomegaly.

The anemia is macrocytic and frequently hypochromic with signs of intense blood formation: young granulocytes, polychromatophilia, reticulocytosis and nucleated red cells. The reticulocytosis may increase to 50 per cent. The pathognomonic sign of the disease is the presence of bartonella bacilliformis on the erythrocytes. The leukocyte count varies; slight leukocytosis is not uncommon but marked leukocytosis is extremely rare in cases without intercurrent infections. There is a shift of the polymorphonuclear series to the left, characterized by the presence of myeloblasts, myelocytes and metamyelocytes. The anemia is normoblastic and not megaloblastic. It is hemolytic and the destruction of erythrocytes is dependent on the presence of bartonella bacilliformis on the erythrocytes. There is no spherocytosis and the fragility of the erythrocytes is normal. Histologically there is evidence of erythrocyte phagocytosis in the cells of the reticulo-endothelial system; the Kupffer cells, the littoral cells of the spleen and the lymph nodes.

The disappearance of the bartonellae from the erythrocytes occurs in a very few days and is called "critical stage" of the anemia. The hematologic changes of this transition are as follows: a change in the shape of the bartonellae from the "bacilliform" to "coccoid" form before complete clearance will take place, an increase in the erythrocyte count, reduction in the indirect hyperbilirubinemia to normal, increase in the number of reticulocytes, reversion to normocytosis, lymphocytosis, reappearance of monocytes and eosinophiles, a "shift to the right" of the polymorphonuclear series. Corresponding with the clearance of bartonella from the erythrocytes, the symptoms dependent on the anemia as well as the fever disappear. Clinical improvement, however, may not parallel the clearance of bartonellae because of intercurrent infections or an atypical course of the bartonellosis itself.

Bartonella bacilliformis anemia has a very severe prognosis, due largely to the occurrence of intercurrent infection by enteric organisms. The treatment today is largely symptomatic as there is no specific agent against the bartonellae bacilliformis infection.

It is suggested that the prognosis may be improved by the use of adequate blood transfusions and the prophylactic use of antibiotics to control intercurrent infection. At present there is no specific agent against bartonella bacilliformis anemia.

ACKNOWLEDGMENT I wish to acknowledge my indebtedness to the attending physicians of "Dos de Mayo," "Arzobispo Loaiza," "San Bartolome" and the Maternity and Children’s Hospitals in Lima, Peru, for permission to study the above patients. I am also very grateful to Dr. Alberto Hurtado for facilities to do the hematologic studies in his Laboratory of Clinical Research, Arzobispo Loaiza, in Lima, and also to Doctors Charles Spurr, Eleanor Hnmphreys and Matthew Block for advice and criticism in the preparation of this manuscript.