Universal PCR assays for the differential detection of all Old World Leishmania species

For the epidemiological monitoring and clinical case management of leishmaniasis, determination of the causative Leishmania species gains importance. Current assays for the Old World often suffer from drawbacks in terms of validation on a geographically representative sample set and the ability to recognize all species complexes. We want to contribute to standardized species typing for Old World leishmaniasis. We determined the ribosomal DNA internal transcribed spacer 1 sequence of 24 strains or isolates, and validated four species-specific polymerase chain reactions (PCRs) amplifying this target. They discriminate L. aethiopica, L. tropica, L. major, and the L. donovani complex, use the same cycling conditions, and include an internal amplification control. Our PCRs amplify 0.1 pg of Leishmania DNA, while being 100% specific for species identification on an extensive panel of geographically representative strains and isolates. Similar results were obtained in an endemic reference laboratory in Kenya. Species could also be identified in clinical specimens. The presented PCRs require only agarose gel detection, and have several other advantages over many existing assays. We outline potential problems, suggest concrete solutions for transferring the technique to other settings, and deliver the proof-of-principle for analyzing clinical samples.