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Visceral Leishmania

Scientific name. Leishmania donovani, Leishmania infantum, Leishmania chagasi

Disease. Kala-azar, visceral leishmaniasis

Geographic distribution. India, China, Bangladesh, Middle East, Mediterranean countries, Tropical Africa, Central and South American countries.

Infection rate. Thousands of new patients appear annually in endemic areas.

Life cycle. The dog is the reservoir host and the vector is the sandfly (Subfamily: Phlebotominae). In mammalian hosts, amastigotes proliferate in the cytoplasm of mononuclear phagocytic cells of the viscera. When a female sandfly sucks blood of the infected dogs, the amastigotes enter into the vector and transform to promastigotes. As the promastigote-carrying sandflies suck blood of dogs or humans, the promastigotes are introduced into the new hosts. They are transformed to amastigotes and invade the phagocytic cells and proliferate. Human hosts are infected by sandfly- biting.

Pathology and clinical symptoms. The mainly involved organs are liver, spleen, and bone marrow. Most of the cells of the organs are destroyed and replaced by granulation tissues. Characteristic symptoms are splenomegaly, hepatomegaly, anemia, and fever. General weakness, emaciation, secondary infection, and pancytopenia are also frequent.

Diagnosis. Detection of amastigotes by biopsy of the liver or spleen confirms the diagnosis. Serology or PCR may support the diagnosis.

Prevention. Protection from sandfly bite is essential.

Sung-Tae Hong

Amastigotes of Leishmania donovani are seen in an impression smear. The nuclei of L. donovaniis are clearly visible (Giemsa stain, 1000x).

DY Min/MH Ahn/JS Ryu

A section of liver tissue from a case of visceral leishmaniasis. Kupffer cells containing many amastigotes are seen. (H&E, 1000x).

DY Min/MH Ahn/JS Ryu

Many sandflies are sucking blood on the skin of a hand. Note the small size of flies.

Sung-Tae Hong

Photograph of the abdomen of a kala-azar (visceral leishmaniasis)patient shows severe hepatomegaly and splenomegaly. Subcutaneous petechial hemorrage is seen around the umbilicus according to the stimulation of plastering after liver biopsy.

Sung-Tae Hong

Histopathological finding of the liver of a kala-azar (visceral leishmaniasis) patient, HE stained, x300. Normal hepatocytes are rare and amastigote-including cells and fibroblasts are increasing.

Sung-Tae Hong

Amastigote stage of Leishmania donovani. Showing Leishman-Donovan (LD) bodies in spleen smear of experimentally infected hamster. Many intracellular and extracellular LD bodies are seen. x400

Hae-Seon Nam