A 27-year-old male presents with fever and loss of
weight. He has spent several months traveling across the countries around the
Mediterranean, Africa and Asia. He admits that he did not bother about
protecting himself from insect bites and was frequently bitten.
On examination he appears to have lost weight, his skin
is pigmented and he has lymphadenopathy and hepatosplenomegaly. Haematology
Aspirates are taken from bone marrow and Giemsa stained
smears of these aspirates show amastigotes.
In this patient the infecting organism is likely to be: