Twelve unlinked microsatellite markers were used to determine the microsatellite profiles of 50 newly and 46
previously typed strains of L. tropica from various Israeli and Palestinian foci. Their microsatellite profiles were
compared to those of 99 previously typed strains of L. tropica from 15 countries. Israeli and Palestinian strains
of L. tropica fell into three different groups, one of which contained 75 of the 96 Israeli and Palestinian strains.
This population separated fromall the others at the first hierarchical level by Bayesian statistics and formed a distinct
monophyletic group on applying genetic distance and allele frequency analyses. The second cluster
contained ten Israeli strains from a specific focus north of the Sea of Galilee,whichwere previously shown to differ
from all other strains of L. tropica in their serological, biochemical and molecular biological parameters. This
clusterwas closely related to clusters comprising strains of L. tropica from Africa. Four Israeli and five Palestinian
strains fell into different genetic entities mostly related to strains from Asian foci of CL.
Importation during numerous migrations of humans and, perhaps, infected reservoir animals in the past and,
now, through modern travel is the most likely explanation for the existence of so many locally encountered genetic
variants of L. tropica in the Israeli-Palestinian region. Geographical and ecological variation may play a role
in expanding the genetic heterogeneity once given importations had become established in different foci. Currently,
one population is expanding in the area comprising almost all of the Palestinian and Israeli strains of L.
tropica isolated since 1996 and investigated in this study, which differ clearly from all other strains ofwhatsoever
origin. This population seems to result from the re-emergence of a previously existing genotype owing to environmental
changes and human activities.
Background: Many cases of cutaneous leishmaniasis (CL) have been recorded in the Jenin District based on their
clinical appearance. Here, their parasites have been characterized in depth.
Methods: Leishmanial parasites isolated from 12 human cases of CL from the Jenin District were cultured as
promastigotes, whose DNA was extracted. The ITS1 sequence and the 7SL RNA gene were analysed as was the
kinetoplast minicircle DNA (kDNA) sequence. Excreted factor (EF) serotyping and multilocus enzyme electrophoresis
(MLEE) were also applied.
Results: This extensive characterization identified the strains as Leishmania tropica of two very distinct sub-types
that parallel the two sub-groups discerned by multilocus microsatellite typing (MLMT) done previously. A high
degree of congruity was displayed among the results generated by the different analytical methods that had
examined various cellular components and exposed intra-specific heterogeneity among the 12 strains.
Three of the ten strains subjected to MLEE constituted a new zymodeme, zymodeme MON-307, and seven
belonged to the known zymodeme MON-137. Ten of the 15 enzymes in the profile of zymodeme MON-307
displayed different electrophoretic mobilities compared with the enzyme profile of the zymodeme MON-137. The
closest profile to that of zymodeme MON-307 was that of the zymodeme MON-76 known from Syria.
Strains of the zymodeme MON-307 were EF sub-serotype A2 and those of the zymodeme MON-137 were either A9
or A9B4. The sub-serotype B4 component appears, so far, to be unique to some strains of L. tropica of zymodeme
MON-137. Strains of the zymodeme MON-137 displayed a distinctive fragment of 417 bp that was absent in those
of zymodeme MON-307 when their kDNA was digested with the endonuclease RsaI. kDNA-RFLP after digestion
with the endonuclease MboI facilitated a further level of differentiation that partially coincided with the
geographical distribution of the human cases from which the strains came.
Conclusions: The Palestinian strains that were assigned to different genetic groups differed in their MLEE profiles
and their EF types. A new zymodeme, zymodeme MON-307 was discovered that seems to be unique to the
northern part of the Palestinian West Bank. What seemed to be a straight forward classical situation of L. tropica
causing anthroponotic CL in the Jenin District might be a more complex situation, owing to the presence of two
separate sub-types of L. tropica that, possibly, indicates two separate transmission cycles involving two separate
types of phlebotomine sand fly vector.
