There are at least three genetically distinct small piroplasms from dogs

The 18S nuclear subunit ribosomal RNA (18S rRNA) gene of small piroplasms i solated from dogs from Okinawa (Japan), Oklahoma, North Carolina, Indiana, Missouri, and Alabama, was isolated and sequenced. Phylogenetic analysis of these sequences and comparisons with sequences from other Babesin, Cytauxz oon, and Theileria species revealed that all canine small babesial isolates , with the exception of isolates from California and Spain, were placed in a group containing the Babesia spp. sensu stricto. Within the Babesia spp. sensu stricto, there was support for separating the small canine piroplasms from the large canine piroplasm, Babesia canis. The isolate from Californi a was in a distinct phylogenetic clade, closely related to babesial isolate s from wildlife and humans from the Western US. The canine isolate from Spa in was closely related to Babesin microti. These results suggest that there are multiple small piroplasm species in dogs. The isolates from the Midwes tern and Eastern US and the one from Japan probably represent a single spec ies with wide geographic distribution. (C) 2000 Australian Society for Para sitology Inc. Published by Elsevier Science Ltd. All rights reserved.