The Journey of Leishmania Parasites within the Digestive Tract of Phlebotomine Sand Flies

Abstract

Leishmaniasis is a vector-borne disease caused by Leishmania parasites and transmitted exclusively by the bite of infected phlebotomine sand flies. In humans, leishmaniasis results in a spectrum of clinical manifestations in which the parasite, sand fly vector and host immune system act in concert to etermine the outcome of disease. Sand flies are the driving force in the spread of leishmaniasis and prevalence of a Leishmania species is entirely governed by the availability of competent vectors. This lends itself to the question “what is a competent vector?” The vectorial competence of sand flies for a particular Leishmania species is complex and multi-factorial. Though extrinsic factors such as geographical distribution of the flies and their feeding preferences can limit the spread of a parasite species, vector competence is mainly determined by factors intrinsic to the fly, some of a general nature and others highly specific, that challenge the successful completion of the Leishmania life cycle within the digestive tract of the fly. Apart from the subgenus Vianna, termed peripylarian Leishmania, whose development includes a stage in the hindgut, all other species of Leishmania that produce disease in mammalian hosts are suprapylarian and confine their development to the midgut and foregut of the sand fly (1).KeywordsCutaneous LeishmaniasisMammalian HostLeishmania SpeciesLeishmania ParasiteLeishmania InfectionThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.