Studies on the pancytopenia of kala-azar.

I T HAS long been recognized that visceral leishmaniasis (kala-azar) is accompanied by marked changes in the peripheral blood, namely; pronounced leukopenia, anemia and thrombocytopenia.'' Pathologically, the disease is characterized by a marked hyperplasia of the reticulo-endothelial system, particularly of the spleen, liver, bone marrow and lymph nodes. As a result of this reticulo-endothelial hyperplasia there is a marked enlargement of the spleen, and a moderate enlargement of the liver and lymph nodes. The bone marrow is hyper-plastic and infiltrated with reticulo-endothelial cells, many of which are parasitized.