Research Synopsis
Emergence of Cutaneous leishmaniasis (CL) in Israel:
Phlebotomine sand flies (Diptera: Psychodidae) transmit the leishmaniases, parasitic diseases that affect large populations in vast areas of the World. There are two major clinical forms of leishmaniasis; cutaneous leishmaniasis (CL) manifests as ugly and persistent (though usually self-curing) ulcers at the site of the infectious bite, while visceral leishmaniasis (VL) is a life-threatening disease caused by massive proliferation of
Leishmania parasites in the spleen, liver, bone marrow and lymphatic system. Three species of
Leishmania are endemic in Israel.
Leishmania infantum is the causative agent of canine and human VL, while
L. major and
L. tropica cause CL.
Increasing incidence of CL caused by
L. tropica was facilitated by the encroachment of rock hyraxes (Procavia capensis), the proven reservoir hosts, upon peridomestic habitats in the Judean Desert and the Galilee. L. major transmitted by Ph. papatasi, has also expanded its range into agricultural areas in the Beit She'an Valley and the north-western Negev, threatening large populations in hitherto non-endemic areas. In this case, the spread was facilitated by the adaptation of the parasite to new rodent hosts, rodents agricultural pests that thrive in great densities in cultivated fields.
Sand fly control:
Control of sand flies is especially problematic because their larval development occurs inside inaccessible niches such as deep cracks and crevices, rodent burrows and caves. Because they do not rely on water for larval development, sand flies are the most prevalent blood-sucking insects affecting humans in deserts and semi-desert regions of Asia and Africa, including the Middle East in. Therefore, control efforts focus mostly on preventing adult flies from reaching human habitation. Such measures include insecticidal spraying, fine-mesh bed nets, indoor diffusible insecticides and vertical mesh barriers.
Visceral leishmaniasis (VL) known as Kala-Azar, is a systemic protozoan infection caused by
L. donovani. In Ethiopia there are 4,000-7,000 diagnosed VL cases a year, and 4.0 million people living in endemic foci. We performed two large cohort studies in northern Ethiopia and conducted numerous diverse studies on reservoirs, vectors and ecological factors. Over 35 publications have been published. The most significant finding was that asymptomatically infected persons outnumbered symptomatic VL cases at least 10:1. This finding underscores the absolute necessity of taking "healthy" persons into account when formulating strategies for curtailing transmission.
Visceral leishmaniasis in North-Eastern Brazil ?:
Although, in Brazil, transmission of VL is thought to be zoonotic with dogs serving as reservoir hosts, in recent years the disease spreading into major cities where there are much fewer dogs. Our research aims to determine whether in cities, sand flies become infected by feeding on asymptomatic humans and or dogs.
MySeq Next Generation Sequencing based Multi Detection Assay for Phlebotomine sand flies:
Only female sand flies suck blood to acquire protein for maturing their eggs. However, both sexes feed on plants to obtain sugars as a source of energy. Sugar meals are acquired by sucking nectar from flowering plants, from honeydew secreted by plant-feeding homopteran insects and by probing of stems and leaves. Several field studies have reported on the attraction of sand flies to specific plants, frequently emphasizing a preference for exotic plants.
Recently, we developed a Next Generation Sequencing (NGS)-based multi detection assay (MiSeq MDA) for wild-caught sand flies that determines sand fly and
Leishmania parasite species (if the female sand fly is infected), identifies the source of blood meals (blood-fed females only), characterizes the prokaryotic gut microbiome and detects the sources of plant meals. To identify the plants upon which sand flies had fed, we relied upon the chloroplast genes ribulose bisphosphate carboxylase large chain (rbcL) and maturase K (matK). Our results indicated a pronounced predilection of several sand fly species, vectors of leishmaniasis in different parts of the world, for feeding on
Cannabis sativa.
