The Ecology and Entomology of the Leishmaniases

Abstract

Pavlosky’s concept of landscape epidemiology underpins all studies on the ecology of Leishmania. The Trinity of vector-parasite-reservoir host can be considered as one entity neatly fitting its habitat. In foci which are well studied, characteristic features of the landscape are often recognised which act as markers revealing places where the parasite is circulating. Examples are: Acacia forests in the Sudan in foci of visceral leishmaniasis (VL) caused by Leishmania donovani transmitted by Phlebotomus orientalis; termite hills in VL foci of East Africa where the vectors of L. donovani are sandflies of one or more species of the subgenus Synphlebotomus; two species of oak trees at particular altitudes in the VL focus in the Cevenne, France, where L. infantum is transmitted by P. ariasi; and chenopod plants in foci of zoonotic cutaneous leishmaniasis (ZCL) in Saudi Arabia and elsewhere where the sandrat Psammomys obesus, is the reservoir host of L. major and P. papatasi is the vector. The marker. features of the landscape are a consequence of the climate and soil but, while recognizable in these and some other foci of the leishmaniases in the Old World, they are generally obscured in the extraordinarily complex habitat of the Neotropical rain forests.