VARIATION IN ECHINOCOCCUS - TOWARDS A TAXONOMIC REVISION OF THE GENUS

Hydatid disease (echinococcosis) is one of the most important parasitic zoonoses and remains a public health and economic problem of global proportions. There are currently four recognized species in the genus Echinococcus: E.granulosus, E.multilocularis, E.oligarthrus, and E.vogeli. Because of the extensive variation in Echinococcus, it is very important to characterize the aetiological agents in different endemic areas to determine transmission patterns, particularly where there is the possibility of interaction between cycles. The first step in a taxonomic revision of the genus Echinococcus is to establish an appropriate species concept. Therefore, the purpose should be to update what is known about the nature and extent of variation in Echinococcus to provide a sound basis for a phylogenetic analysis. The current classification within the genus Echinococcus is not compatible with historical relationships between taxa. Phylogenetic analysis of DNA sequence data provides no support for the concept that E.grunulosus is a monophyletic group and it cannot be considered an evolutionary species. There is an urgent need for the molecular characterization of strains of E. multilocularis as well as strains of Echinococcus in lions and cervids, so that this taxonomic revision can be completed. © 1995 Academic Press Inc.