Visceral leishmaniasis — DTM&H MCQ

Correct answer: D — rk39 serology followed by parasitological confirmation where feasible

The correct answer is D, rk39 serology followed by parasitological confirmation where feasible. This man from eastern Sudan has the classic triad of visceral leishmaniasis (kala-azar): prolonged fever, massive splenomegaly and pancytopenia, with polyclonal hypergammaglobulinaemia reflecting chronic reticuloendothelial stimulation. rK39 immunochromatographic testing is the recommended first-line, point-of-care diagnostic in endemic areas because it is rapid and needs no laboratory infrastructure, but its sensitivity is reduced in East African foci such as Sudan compared with the Indian subcontinent, so a negative or borderline result in this setting must be followed by parasitological confirmation (splenic, bone marrow or lymph node aspirate microscopy or PCR) before treatment decisions are finalised. This staged approach balances practicality with diagnostic accuracy in exactly the population this patient comes from. Why the other options are wrong: B. Thick blood film for malarial gametocytes: malaria can cause fever and splenomegaly but does not typically produce three months of illness with massive splenomegaly and marked pancytopenia plus hypergammaglobulinaemia; gametocytes are not diagnostic of severity or explain this syndrome. C. Urine microscopy for terminal-spined eggs: this detects Schistosoma haematobium, which causes haematuria and bladder pathology, not a chronic febrile wasting illness with pancytopenia. A. Stool culture for Salmonella Typhi: typhoid causes fever and can cause splenomegaly but is typically a shorter, acute illness without pancytopenia or hypergammaglobulinaemia of this degree, and stool culture is an insensitive diagnostic method. E. Chest radiograph for miliary tuberculosis alone: TB can mimic chronic fever and splenomegaly, but relying on a chest radiograph alone, without microbiological confirmation, is inadequate and does not fit the specific geographic and haematological clues pointing to leishmaniasis. Key point: In a patient from an East African leishmaniasis focus with fever, massive splenomegaly, pancytopenia and hypergammaglobulinaemia, use rk39 as the initial test but confirm parasitologically because serological sensitivity is lower in East Africa than in South Asia.

Reference: Cochrane Database of Systematic Reviews: Rapid tests for the diagnosis of visceral leishmaniasis in patients with suspected disease (2014), summarising rK39 ICT performance and the need for regional validation, https://pubmed.ncbi.nlm.nih.gov/24947503/