Schistosoma mansoni and Biomphalaria: Past history and future trends

摘要: Schistosoma mansoni is one of the most abundant infectious agents humankind. Its widespread distribution permitted by broad geographic range susceptible species freshwater snail genus Biomphalaria that serve as obligatory hosts for its larval stages. Molecular phylogenetic studies suggest originated in Asia, and a pulmonate-transmitted progenitor colonized Africa gave rise to both terminal-spined lateral-spined egg groups, latter containing S. mansoni. likely appeared only after trans-Atlantic dispersal from Neotropics Africa, an event that, based on present African fossil record, occurred 2-5 million years ago. This parasite became tropical then entered 'New World with slave trade. It prospered because remarkably productive host, B. glabrata, was widely distributed there. Indeed, similar glabrata may have given Biomphalaria. has since spread into other Neotropical mammalian hosts. The state flux. In Egypt, nearly completely replaced haematobium Nile Delta, regions country. A host snail, straminea, been introduced Asia there evidence transmission Nepal. Dam barrage construction lead epidemic Senegal, continues Brazil. Because competition aquatic environmental changes, consequently become less Caribbean islands. Control using praziquantel oxamniquine reduced global prevalence but control difficult sustain, can develop tolerance/resistance praziquantel, raising concerns about future efficacy. legitimate concerns, unlikely be option efforts. Global warming will impact mansoni, magnitude nature effects are poorly understood.