The Effect of Temperature on <I>Leishmania</I> (Kinetoplastida: Trypanosomatidae) Development in Sand Flies

Abstract

The spread of leishmaniasis to areas where it was previously considered nonendemic has been recently found in the New and Old Worlds, and climate changes are suspected as a crucial factor responsible for this spread. Ambient temperature is known to signicantly affect the metabolism of sand ies and their developmental times, but little is known about the effect of temperature on the Leishmania life cycle in vectors. This study assesses the effect of temperature on the development of two closely related New World Viannia species, Leishmania braziliensis and Leishmania peruviana, in the permissive vector Lutzomyia longipalpis, and on the development of New and Old World Leishmania infantum in its natural vectors Lu. longipalpis and Phlebotomus perniciosus, respectively. The mountain species L. peruviana developed well in sand y females kept at 20C, whereas at 26C, most infections were lost during the defecation of bloodmeal remains; this suggests an adaptation to the slower metabolism of sand ies living at lower ambient temperature. On the contrary, L. infantum and L. braziliensis developed well at both temperatures tested; heavy late-stage infections were observed in a majority of sand y females maintained at 20C as well 26C. Frequent fully developed infections of L. infantum and L. braziliensis at 20C suggest a certain risk of the spread of these two Leishmania species to higher latitudes and altitudes.