A villager in Bihar presents with fever, massive splenomegaly, weight loss and pancytopenia. Splenic aspirate smear stained with Giemsa shows oval bodies with a large nucleus and a kinetoplast (rod-shaped) within macrophages. Which of the following laboratory serological tests has the highest sensitivity for diagnosis of visceral leishmaniasis in endemic settings?

• A Aldehyde (formol-gel) test
• B rK39 immunochromatographic strip test ✓
• C Direct agglutination test (DAT)
• D Complement fixation test

Explanation

The rK39 ICT strip (based on a kinesin-related antigen of L. chagasi/donovani) has sensitivity of 93–100% and specificity of >98% for visceral leishmaniasis in the Indian subcontinent and is the recommended point-of-care test by WHO. The formol-gel (aldehyde) test detects polyclonal hypergammaglobulinaemia and is non-specific, turning positive in many other conditions. DAT has good sensitivity but requires titration, refrigeration and trained personnel. Complement fixation is obsolete in this context.

Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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