Genotypic status of Babesia microti within the piroplasms

For resolution of the controversial taxonomic status of Babesia microti in relation to other Babesia and Theileria spp. a phylogenetic analysis of an American and a German B. microti strain was performed on the basis of seque nces of the small-sub-unit rRNA gene (rDNA) using distance-matrix, maximum- parsimony, and maximum-likelihood algorithms. Both B. microti isolates clea rly separated from a group containing other Babesia spp. as well as from a second group consisting of Theileria spp. Interestingly, the B. microti iso lates clustered in a monophyletic group together with other piroplasm speci es of unclear taxonomic status, B. rodhaini, and a recently described small canine piroplasm species. These results support the existence of a third t axonomic entity of equal rank besides the Babesiidae and Theileriidae.