Which is caused by Leishmania donovani?

Appeared in: PGICH Noida NO-2025

Explanation

Kala-azar, also known as visceral leishmaniasis, is directly caused by the protozoan parasite Leishmania donovani.
The parasite is transmitted to humans through the bite of infected female sandflies.
Once in the body, L. donovani infects cells of the immune system, particularly macrophages in the spleen, liver, and bone marrow, leading to the characteristic symptoms of the disease.
The name Kala-azar means 'black sickness' and refers to the hyperpigmentation of the skin seen in advanced stages of the disease in some patients.

Option A: Scrub typhus is a bacterial infection, not a protozoal one. It is caused by Orientia tsutsugamushi.
Option B: Malaria is caused by a different type of protozoan parasite, belonging to the Plasmodium genus.
Option D: Filariasis is caused by a parasitic worm (helminth), not a protozoan. The causative agent is typically Wuchereria bancrofti.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Causative agents of vector-borne diseases as background academic context rather than a clinical decision trigger.
For a nurse, knowing the specific causative agent and vector is crucial for patient education on prevention (e.g., using bed nets for mosquitoes, avoiding sandfly bites).
Differential diagnosis of fever in endemic areas is critical. A patient with prolonged fever and splenomegaly from Bihar, India, would raise high suspicion for Kala-azar, whereas the same symptoms in a patient from a different region might point towards malaria or another infection.
What if? If a patient presents with fever and an enlarged spleen but has a recent travel history to sub-Saharan Africa instead of eastern India, the suspicion for malaria (P. falciparum) would be much higher than for Kala-azar, guiding initial diagnostic tests.

How to Approach the Question

First, identify the core of the question, which is to match a specific pathogen, Leishmania donovani, to the disease it causes.
This is a factual recall question from microbiology or community health nursing.
Systematically review the options provided.
Recall or deduce the causative agent for each listed disease: Scrub typhus (bacterium), Malaria (Plasmodium), Kala-azar (Leishmania), and Filariasis (worm).
Match Leishmania donovani from the question stem with the correct disease from your review.
Select the option that correctly links the pathogen to the disease.

Concept Tested & Keywords

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E6 Pathology- ROBBINS & COTRAN PATHOLOGIC BASIS OF DISEASE 10TH Ed p. 395-397

E6 Ghai Essential Pediatrics(pp 26-904 of 913) p. 279-281

Practise the full PGICH Noida NO-2025

Attempt every question from this paper in a timed mock, then review the full solution for each one.