Leishmania donovani is the cause of visceral leishmaniasis or Kala Azar disease.
Disease / Pathogenesis
Leishmania donovani will cause a disease that unlike other leishmania will affect the visceral organs preferentially. The disease causes fever, and weight loss. But most importantly is the affects on the visceral organs which lead to hepato and splenomegaly.Without treatment the infection leads to death. The disease is particularly dangerous to the immunocompromised such as persons with HIV.
A skin condition which occurs in in some individuals after successful treatment may appear months to years later. This condition is known as post-kale-azar dermal leishmaniasis or PKDL. While not life threatening the skin condition can be disfiguring and produce stigmatization within society. These persons can still transmit the disease.
Location in the Host
Leishmania donovani localizes primarily in the visceral organs of the infected host.
Geographic Distribution
Leishmania donovani is found primarily in impoverished areas of Brazil, Africa (Ethiopia and Kenya, Somalia, South Sudan and Sudan), India. It is endemic in at least 60 countries including Iran.
Life Cycle
Leishmania donovani is transmitted by the bite of the female sandfly.

Morphology & Diagnosis
Leishmania donovani is diagnosed by the detection/identification of amastigotes in tissue biopsies of infected visceral organs and a good clinical history indicating the high likely hood of exposure to the parasite.