Effects of land use type, spatial patterns and host presence on Leishmania tropica vectors activity

Yoni Waitz,David Meir,Shlomit Paz,Dan Malkinson

doi:10.1186/s13071-019-3562-0

Abstract

BackgroundLeishmaniasis is a vector-borne disease, caused by the infection of Leishmania parasites which are transmitted by the bite of infected female phlebotomine sand flies. Leishmania tropica is transmitted by Phlebotomus sergenti and Phlebotomus arabicus while the main reservoir host is the rock hyrax. A marked increase in the incidence of cutaneous leishmaniasis (CL) caused by L. tropica has been detected in recent years in Israel; it is associated with infections which have emerged in new urban and rural foci. The objective of this study is to contribute to a better understanding of the preferred habitat, spatial activities and host-sand fly relationships of both species of vectors within various types of land use.MethodsUsing CDC-type traps, we investigated the activity levels of sand flies. A field survey was conducted in 2016 at Elifelet, an agricultural village characterized by various types of land use. Movement patterns of P. sergenti between rock-piles were investigated by using colour-marked sugar baits and analyses of recapture patterns. In 2017, a survey was conducted in the hilly Jordan River area, by comparing sand flies and rock hyrax activities in relation to the size of rock-piles and vegetation cover.ResultsBoth sexes of both species were found to have a clear preference for rocky habitats over other land use types in rural landscapes. Movement patterns of P. sergenti were characterized by their high presence close to the rocks and an exponential decrease in their recapture, commensurate with the distance from the rocks. Host-sand fly relationships were found to have a higher correlation between rock hyrax activity levels for females than for males of both species of sand flies. Males exhibited the strongest association with the size of rock-piles.ConclusionsThe results suggest a strong affinity of both phlebotomine vector species to the rocky habitats of the Mediterranean areas. We suggest that rock-piles are associated with populations of rock hyraxes attracting female sand flies seeking blood sources. Rapid human population growth, coupled with intensive land-use changes and the creation of artificial rock-piles, which created potential habitats for both vectors and hosts in the proximity of many settlements, have increased the prevalence of L. tropica among the human population in the region.

Highlights

Leishmaniasis is a vector-borne disease, caused by the infection of Leishmania parasites which are transmitted by the bite of infected female phlebotomine sand flies
In the eastern Mediterranean basin, both Leishmania major and Leishmania tropica cause cutaneous leishmaniasis (CL) which is manifested as skin sores, while Leishmania infantum causes visceral leishmaniasis (VL) which affects various internal organs, usually the spleen, liver and bone marrow [3]
The sand fly activity patterns in the land‐use categories The sand fly activity patterns of both species (P. sergenti and P. arabicus) and sexes were best fit by a negative binomial distribution; significant differences between land use types were detected (Table 1)

Summary

Introduction

Leishmaniasis is a vector-borne disease, caused by the infection of Leishmania parasites which are transmitted by the bite of infected female phlebotomine sand flies. A marked increase in the incidence of cutaneous leishmaniasis (CL) caused by L. tropica has been detected in recent years in Israel; it is associated with infections which have emerged in new urban and rural foci. The manifestation of zoonotic diseases requires the presence of humans, animal hosts, and vectors capable of transmitting them. Leishmaniasis is a vector-borne disease, caused by infection of Leishmania parasites which are transmitted by the bite of infected female Phlebotomine sand flies. In the eastern Mediterranean basin, both Leishmania major and Leishmania tropica (the main parasites in Israel) cause cutaneous leishmaniasis (CL) which is manifested as skin sores, while Leishmania infantum causes visceral leishmaniasis (VL) which affects various internal organs, usually the spleen, liver and bone marrow [3]

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