Diagnostic Accuracy of the Leishmania OligoC-TesT and NASBA-Oligochromatography for Diagnosis of Leishmaniasis in Sudan

Abstract

BackgroundThe Leishmania OligoC-TesT and NASBA-Oligochromatography (OC) were recently developed for simplified and standardised molecular detection of Leishmania parasites in clinical specimens. We here present the phase II evaluation of both tests for diagnosis of visceral leishmaniasis (VL), cutaneous leishmaniasis (CL) and post kala-azar dermal leishmaniasis (PKDL) in Sudan.MethodologyThe diagnostic accuracy of the tests was evaluated on 90 confirmed and 90 suspected VL cases, 7 confirmed and 8 suspected CL cases, 2 confirmed PKDL cases and 50 healthy endemic controls from Gedarif state and Khartoum state in Sudan.Principal FindingsThe OligoC-TesT as well as the NASBA-OC showed a sensitivity of 96.8% (95% CI: 83.8%–99.4%) on lymph node aspirates and of 96.2% (95% CI: 89.4%–98.7%) on blood from the confirmed VL cases. The sensitivity on bone marrow was 96.9% (95% CI: 89.3%–99.1%) and 95.3% (95% CI: 87.1%–98.4%) for the OligoC-TesT and NASBA-OC, respectively. All confirmed CL and PKDL cases were positive with both tests. On the suspected VL cases, we observed a positive OligoC-TesT and NASBA-OC result in 37.1% (95% CI: 23.2%–53.7%) and 34.3% (95% CI: 20.8%–50.9%) on lymph, in 72.7% (95% CI: 55.8%–84.9%) and 63.6% (95% CI: 46.6%–77.8%) on bone marrow and in 76.9% (95% CI: 49.7%–91.8%) and 69.2% (95% CI: 42.4%–87.3%) on blood. Seven out of 8 CL suspected cases were positive with both tests. The specificity on the healthy endemic controls was 90% (95% CI: 78.6%–95.7%) for the OligoC-TesT and 100% (95% CI: 92.9%–100.0%) for the NASBA-OC test.ConclusionsBoth tests showed high sensitivity on lymph, blood and tissue scrapings for diagnosis of VL, CL and PKDL in Sudan, but the specificity for clinical VL was significantly higher with NASBA-OC.

Diagnosis of leishmaniasis

“…Recently, an evaluation of an oligochromatography-PCR for diagnosis of VL, cutaneous leishmaniasis (CL), and post kala-azar dermal leishmaniasis (PKDL), showed a high sensitivity (> 95%) on lymph, blood, and bone marrow samples from confirmed VL patients [105].…”

Expanding the MDx toolbox for filarial diagnosis and surveillance

“…Indeed, highlyefficient RNA-based isothermal technologies are available including RT-LAMP [52] for Leishmania [85] and Plasmodium [86], signal-mediated amplification of RNA technology (SMART) [87], and nucleic acid sequence-based amplification (NASBA) [88], also known as transcription-mediated amplification (TMA) [89]. A commercially available kit using NASBA technology is available for Leishmania (Leishmania OligoC-TesT, Coris Bioconcept, Belgium) [90].…”

Molecular Diagnosis of Leishmaniasis, Species Identification and Phylogenetic Analysis

“…Several QT-NASBA assays have been developed for the detection of Leishmania parasites including QT-NASBA combined with electro-chemiluminescence (ECL) [57,58] and QT-NASBA combined with oligochromatographic technology (OC) [12,59] for the detection of NASBA products. The QT-NASBA assays developed, are commonly based on amplification of single-stranded 18S ribosomal RNA sequences [12,57,58,60,61]. This target is considered to be highly efficient for the diagnosis of leishmaniasis as each parasite contains a large number of copies of the 18SrRNA gene [62] while also the cytoplasm is assumed to contain approximately 104 rRNA copies [62].…”