Question

Kala-azar is caused by
(a) Entamoeba
(b) Leishmania dono vani
(c) Trypanosoma gambiense
(d) Leishmania trophica

Answer 1

Kala-azar also known as visceral leishmaniasis, Kala jwar, black fever, etc. It is a disease occurring in tropical and subtropical Asia and Africa, tropical S.America, and Mediterranean areas. It is a protozoan disease. Major clinical features include eruptive pyrexia, generalized granular enlargement of spleen and liver, dry, rough, and often pigmented dark skin, brittle hairs, which may fall out shortly, emaciation and anemia in the advanced stage.

Complete step by step answer:
Kala-azar is caused by parasitic haemoflagellate Leishmania Donovani, an intracellular endoparasite living in macrophages of the spleen, liver, intestinal mucosa, lymph glands, bone marrow, etc. of man. The disease spreads through the bite of a sandfly. The lifecycle of L. donovani is completed in two hosts, namely man and sandfly. Its amastigote stage occurs in man and the promastigote stage in sandfly. In the reticuloendothelial cells of man, the amastigote forms undergo continuous multiplication by rotated binary fission. When the host cell becomes packed with parasites, they rupture and release parasites into the blood circulation. Natural transmission of Leishmania is mostly inoculative and it occurs when the female sandfly bites human beings for its blood meal. Direct man to man transmission includes; congenital infection of a child in utero, transmission through blood transmission, transmission through coitus, etc. In normal cases, transmission from man to flies occurs when the flies bite leishmania infected persons. Together with blood, they suck in large numbers of cells also, which contain amastigote parasite.
So, the correct answer is ‘(b) Leishmania dono vani’.

Additional information:
- Kala-azar is almost endemic in nature, and it regularly occurs in specific areas and populations
- Kala-azar is usually more prevalent in villages where houses have mud walls and earthen floors, and cattle and other livestock are kept close to human dwellings.
- There are two major pathological changes namely; the proliferation of histiocytes and secondary infiltration of spleen, liver, lymph nodes, and bone marrow.
- Visceral Leishmaniasis has a profound immunosuppressive effect. It may disrupt the immune mechanism, allowing secondary bacterial invasion which the patient cannot resist or defend.
- In some Kala-azar patients, non-ulcerative nodular cutaneous lesions may be formed.

Note: Studies have revealed that people with HIV infection are nearly 400 times more likely to become victims of kala- azar AIDS and Kala- azar make up a deadly cocktail. Co- infected patients are at a greater risk of death since both diseases reinforce each other and weaken the immune system of the patient. Hence, Kala- azar cannot be completely eradicated, without addressing kala- azar - HIV co-infection.