The 40 Israeli and 56 Palestinian strains included in the data set were isolated between 1949 and 2011. All Palestinian and 27 of the Israeli strains were obtained from human cases of CL. Eleven strains from Israel were isolated from sand fly vectors, six from P. sergenti and five from P. arabicus, one strain from a rock hyrax and one from a human case of VL. The collection sites of all strains are summarized in Table 3 and shown in Figure 32. Both territories, Israel and Palestine, should be considered as one area for several reasons. First, they cover only a relatively small area and, despite the political situation and the boarder separating these two countries, people are extensively travelling between them. Furthermore, the WHO code gives the country where human cases were diagnosed, but patients might have gotten infected elsewhere.
Figure 32. Collection sites of the strains of L. tropica in Israel and Palestine. The circles are coloured according to their assignment by the Bayesian statistics; yellow, “Israel/Palestine”, red, “Northern Galilee”, grey, “India/Palestine”. Jerusalem and Tel Aviv are indicated for better orientation.
In total, 59 different microsatellite profiles were determined for the 96 Israeli and Palestinian strains of L. tropica studied herein. Twenty-seven Israeli and Palestinian strains collected between 2001 and 2010 shared the same microsatellite profile, LtroMS 041 (Table 11). Another profile, LtroMS 042 was presented by three strains and nine other profiles by two strains each. The remaining 48 strains from this area had unique microsatellite profiles. None of the profiles of Israeli and Palestinian strains were shared with strains of other geographical origins.
The strains of L. tropica from Israeli and Palestinian foci were found in four different genetic entities (Figure 16). At the highest hierarchical level, the Bayesian clustering approach assigned 75 of the Israeli and Palestinian strains of L. tropica to one population named “Israel/Palestine” together with one strain from Egypt, MHOM/EG/ 1990/LPN65 (Figure 16) and separated them from all other strains under study. The close genetic relationship of these strains as well as their large genetic distance to all other strains tested (Table 17) was confirmed by all subsequent analyses. They formed
monophyletic groups in the NJ tree (Figure 17) and the network (Figure 18) and were also remotest to all other groups of L. tropica in the FCA (Figure 19). Low heterozygosity was confirmed for this population by the descriptive statistics (Ho=0.035, Table 16).
The remaining 21 Israeli and Palestinian strains could be assigned to distinct genetic entities only at cluster or group levels. Ten Israeli strains isolated from human cases of CL, a hyrax, P. capensis, and from different sand fly vector species, P. sergenti and P. arabicus, formed the cluster “Northern Galilee” identified by Bayesian statistics and confirmed by genetic distance analyses, the NJ tree and the network, and the FCA.
The other 11 strains belonged to different genetic clusters and groups of the sub-population “Asia” (Figure 12). The group “India/Palestine” of the cluster “Middle East/India” contained three
Palestinian strains isolated in the Jenin District. This group was, again, confirmed by all approaches used, although the monophyletic nature of this group was not as strong as in the previously
mentioned genetic entities of Israeli and Palestinian strains. One strain each from Israel and Palestine was found in the group “IL/PS/JO/IN”. Another two strains, both from the Jenin District in Palestine, could not be assigned clearly to any of the three groups of the cluster “Middle East/India”. The group “IL/PS/JO/IN” should be, in fact, not considered as a confirmed genetic entity but rather as an artificial group created by the Bayesian statistics approach which has the disadvantage to summarize all strains which do not have sufficient genetic similarity to any of the other groups, into a new one. The group “old strains/TR” of the cluster “old strains/Turkey” identified by the Bayesian clustering approach included three strains from Israel isolated in 1949, 1959 and 1990 and one strain from Palestine isolated in 2002. Two of these strains, MHOM/IL/1949/LRC-L43 and
MHOM/PS/2002/18JnF4, clustered together with the old strains from other Asian foci in all analyses. However, the strains MHOM/IL/1990/P283 and MHOM/IL/1959/LRC-L22 were outliers in the NJ tree and the network. Because of the great differences between the results of the different approaches the genetic relationship between these latter strains could not be confirmed.
The separation of the Israeli and Palestinian strains into several clusters is in agreement with earlier studies [30, 108]. According to Azmi et al., 12 Palestinian and three Israeli strains of L. tropica belonged to two clades by using a kDNA-RFLP typing approach, which was in accordance to MLEE typing, EF serotyping and the MLMT results of Schwenkenbecher et al. The present study, which included 12 of the strains analysed in the kDNA-RFLP study, corroborated the existence of these two clades. Three strains which had been assigned to clade A were part of the sub-population “Asia”, while the nine strains assigned to clade B were part of the sub-population “Israel/Palestine”. The strong monophyletic nature of the population “Israel/Palestine” suggests that these parasites might have evolved from one single founder strain of L. tropica. This could have been the oldest strain in this population, MHOM/EG/1990/LPN65, which was isolated on the Sinai Peninsula. It might have been introduced into Israel/Palestine and, subsequently, spread throughout this area.
Transmission of L. tropica in Israeli and Palestinian foci is likely to be zoonotic as has been also suspected for several African foci but is in contrast to the anthroponotic transmission reported for other Asian foci [42]. Rock hyraxes infected by L. tropica have been found in different Israeli foci and the animals were shown highly abundant in Palestinian areas endemic for L. tropica. They are therefore incriminated as the parasites´ natural mammalian reservoirs. Recent house building activities of the Israeli population in close proximity to the natural habitats of the rock hyraxes, possibly, facilitated the transmission of the L. tropica parasites from the animals to humans and vice versa [31]. Interestingly, the “Northern Galilee” cluster is related to the African strains of L. tropica in all analysis performed and rock hyraxes are the proven animal reservoir for L. tropica in Kenya and Namibia [2]. Thus, the Galilean strains might have been introduced into Israel from Africa by infected humans or animals. Hyraxes of the species P. capensis are known to live along the Great Rift Valley which stretches from Syria via the Jordan Valley through East Africa and ends in South Africa [109]. Based on the above findings, the establishment of genetically different L. tropica parasites in Israeli and Palestinian foci is, most probably, the consequence of their multiple importations into this area rather than due to diversifying evolution from a common ancestor. The multiple introductions of genetically different L. tropica parasites into Israel and Palestine is probably the result of extensive travelling and migration of humans or animals, from a great variety of countries into this region, which started several thousand years ago and is still ongoing.