Aetiology and Epidemiology: Overview

Abstract

The striking feature of the aetiology and epidemiology of the leishmaniases is gualitatitive complexity. in no other parasitic genus infecting man is there such a diversity of species and strains, variety of pathogenic manifestations, plethora of reservoir hosts and ecological richness of transmission patterns. Add to this the small size, species complexity and taxonomic horrors of the vector sandflies and it is remarkable that epidemiologists do not abandon the field to those rudely called by Lord Rutherford “stamp collectors” (whom he contrasted with physicists!) the task of an overview must therefore be to see how far we can progress to either finding order within this exuberant complexity, or if this is not yet possible, how far some order may be imposed, so that our understanding can be used to predict and thus to control human and animal leishmaniasis.