Identification of Leishmania tropica from micro-foci of cutaneous leishmaniasis in the Kenyan Rift Valley.

We performed diagnosis and species identification of parasites in lesion samples from suspected cutaneous leishmaniasis patients in four villages, three of which are in a known Leishmania tropica endemic region in Kenya. Samples were analyzed both by microscopy and PCR for Leishmania, and typed by an assay using four ribosomal DNA-based species-identification PCRs. The lesions were demonstrated to be caused by L. tropica, which confirms the re-emergence of cutaneous leishmaniasis from this species after a period of reduced incidence in the endemic zone. Our report highlights the importance of an intervention and sustained Leishmania control program.

Evolution of the Leishmania braziliensis species complex from amplified fragment length polymorphisms, and clinical implications.

In order to get more insight into its evolution and geographical distribution, we investigated the Leishmania (Viannia) braziliensis species complex using amplified fragment length polymorphisms and sequencing of a heat-shock protein 70 gene fragment. Previously, several assays had alluded to the high genetic diversity of the group, and single-locus assays typically identified two species, i.e. L. braziliensis and Leishmania peruviana, with occasional genetic signatures of both in the same strain. By analysis of 53 parasite isolates from Peru, and eight additional ones from other countries, we identified an atypical L. braziliensis cluster, and confirmed the origin of L. peruviana from the L. braziliensis cluster during the colonization of the western Andean coastal valleys. We discuss the clinical and taxonomical implications of our findings in relation to currently used species typing assays.

Natural Leishmania donovani/Leishmania aethiopica hybrids identified from Ethiopia.

Natural hybridization events have been demonstrated between closely and distantly related Leishmania groups despite a predominantly clonal and endogamically sexual mode of reproduction. Here we report the first natural hybrid between Leishmania aethiopica and Leishmania donovani, as evidenced from the analysis of several clones from strain MHOM/ET/94/ABAUY. Targeted species-identification PCRs revealed the presence of both genotypes, and amplified fragment length polymorphisms indicated that the clones are genetically in an intermediate position between both parental species, being more closely related to L. aethiopica. The possible scenario facilitating hybrid formation is not clear, but is discussed in relation to epidemiological data.

Leishmania AFLP: paving the way towards improved molecular assays and markers of diversity.

Diversity, phylogenetic, and population genetic studies of the genus Leishmania, causative agent of leishmaniasis, nowadays generally involve multilocus microsatellite and multilocus sequence typing. Even though these are well established and useful applications, amplified fragment length polymorphisms (AFLP) can provide complementary information. In addition, as the technique essentially probes the entire genome at random, without prior sequence knowledge, it is ideally suited as a screening tool for molecular markers linked with biological and clinical traits. We developed an AFLP protocol adapted to the Leishmania genome, tested its repeatability, and validated it on a panel of samples from the Leishmania donovani complex previously analyzed by multiple molecular tests. The technique proved highly reproducible, and showed that genetic relationships between L. donovani strains generally reflect geographic distance. Four main groups were identified: Leishmania infantum, African L. donovani, Indian L. donovani, and a mixed group consisting of L. donovani from India and Africa. Results were highly congruent with previous analyses on essentially the same sample set, indicating that the developed assay produces trustworthy data. This opens possibilities for application in studies of speciation and population dynamics. Moreover, it allows random screening of the entire Leishmania genome for linkage with biological and clinical parasite properties, such as fitness, drug resistance, and disease profile.