Leishmania donovani
Leishmania species, amastigote 
  or Leishman-Donovan bodies, Giemsa’s stain. These organisms are intracellular 
  in the reticuloendothelial cells, particularly those of the spleen, liver, and 
  bone marrow. This slide is from a bone marrow preparation from a case of visceral 
  leishmaniasis (Leishmania donovani).