Reliable diagnosis of post‐kala‐azar dermal leishmaniasis ( PKDL ) using slit aspirate specimen to avoid invasive sampling procedures

Objective Confirmatory diagnosis of post‐kala‐azar dermal leishmaniasis ( PKDL ) is primarily based on invasive skin biopsy procedure. We evaluated the utility of minimally invasive slit aspirate specimen for serological and molecular diagnosis of PKDL . We compared the PKDL diagnosis using slit aspirate and skin biopsy specimens from the same patients. Methods Serological diagnosis using rK39 strip test was performed with serum and slit aspirate sample; molecular diagnosis for parasite detection and quantification was carried out by quantitative real‐time PCR ( Q ‐ PCR ) with skin biopsy and slit aspirate sample. Results The rK39 serological strip test was positive in all PKDL cases with both slit aspirate and serum samples ( n  = 50) and negative in all control cases ( n  = 24), giving a sensitivity of 100% (95% CI : 92.9–100%) and a specificity of 100% (95% CI : 86.2–100%). Quantitative ‐ PCR detected parasite in all PKDL slit aspirates ( n  = 50, sensitivity = 100%, 95% CI : 92.9–100%) and tissue biopsies ( n  = 46, sensitivity = 100%, 95% CI : 92.3–100; it was negative in all controls including dermal tissues ( n  = 24) and slit aspirates ( n  = 24), giving specificity of 100% (95% CI : 86.2–100%). The parasite load in tissue and slit aspirate samples was significantly ( P  < 0.0001) correlated ( r  = 0.82). Conclusions Slit aspirates are a simpler and minimally invasive sampling technique for initial screening by serology followed by confirmatory diagnosis of PKDL with microscopy and/or Q ‐ PCR . The simplified procedure has the potential for epidemiological studies and assessment of cure in PKDL .