Paper II
Question
Laboratory diagnosis of kala azar
Answer
Laboratory diagnosis of kala-azar (visceral leishmaniasis), caused by Leishmania donovani:
- Demonstration of amastigotes (LD bodies) in Giemsa-stained smears of splenic aspirate (highest sensitivity, but risk of haemorrhage) or bone marrow aspirate (safer, standard alternative).
- rK39 rapid diagnostic test — immunochromatographic strip test detecting antibody against a recombinant Leishmania antigen; rapid, field-deployable, now the first-line diagnostic tool.
- Serology — direct agglutination test (DAT), ELISA.
- Culture — on NNN (Novy-MacNeal-Nicolle) medium, demonstrating promastigote growth.
- PCR — highly sensitive, increasingly used where available.
- Supportive findings: pancytopenia, hypergammaglobulinaemia (with albumin-globulin ratio reversal), raised ESR.