Abstract
In the past few years, the development of molecular systematic methods in phylogenetic studies has considerably increased our knowledge of the historical biogeography of schistosomes (Trematoda : Schistosomatidae) and some of their intermediate snail hosts across the continents. Concomitantly, at a more restricted geographic scale, host and parasite population structures have been characterized, using neutral molecular markers, providing an improved understanding of coevolutionary dynamics between hosts and parasites and their epidemiological implications. Finally, at a microspatial scale, analyses of the genotypic composition of parasite infrapopulation, within both definitive and intermediate hosts, have provided useful information on transmission and recruitment processes in the field. Based on recent published studies, we will review (i) phylogeographical hypotheses for the origin and radiation of Schistosoma in Asia, India, Africa, and South America, (ii) new Schistosoma species recently described, (iii) coevolutionary processes acting in fragmented population, (iv) local patterns by which hosts may acquire schistosome infection and factors which are likely to enhance diversity, providing opportunities for parasite adaptation to host and/or environmental changes