Background: PCR based diagnosis for Visceral Leishmaniasis (VL), despite numerous published primers, remains far from being applied in the field. The present study was planned to design a Leishmania specific diagnostic assay and to evaluate its sensitivity and specificity on a sample size, which to the best of our knowledge is the largest ever screened in one study. Methods: Leishmania specific primers were developed using 18S rRNA gene and their sensitivity was evaluated on 500 parasitologically confirmed patients with VL and 25 Post Kala-azar Dermal Leishmaniasis (PKDL) patients. Specificity was calculated on 250 healthy endemic controls, 250 healthy non endemic controls and 250 non leishmanial diseases like malaria. Results: Our PCR assay had a sensitivity of 87.8% (95%CI: 84.189.8) using 200 µL of patient's peripheral-blood. Specificity was absolute in non-endemic healthy controls and in subjects with different diseases while in endemic controls it was 84% (95%CI: 78.988.0). Its overall specificity was 94.6% (95%CI-92.896.1). Conclusions: The PCR assay developed is sensitive enough to detect the 18S rRNA gene in an amount equivalent to a single parasite or less in a one million human cell environment. The high sensitivity of this PCR diagnostic test with relatively non-invasive peripheral blood sampling method opens up the possibility of its deployment in field for the routine diagnosis of VL.
Srivastava, P., Mehrotra, S., Tiwary, P., Chakravarty, J., & Sundar, S. (2011). Diagnosis of indian visceral leishmaniasis by nucleic acid detection using pcr. PLoS ONE, 6(4). https://doi.org/10.1371/journal.pone.0019304