Prevalence, distribution, and diversity of cryptic piroplasm infections in raccoons from selected areas of the United States and Canada

The order Piroplasmida contains a diverse group of intracellular parasites, many of which can cause significant disease in humans, domestic animals, and wildlife. Two piroplasm species have been reported from raccoons (Procyon lotor), Babesia lotori (Babesia sensu stricto clade) and a species related to Babesia microti (called B. microti-like sp.). The goal of this study was to investigate prevalence, distribution, and diversity of Babesia in raccoons. We tested raccoons from selected regions in the United States and Canada for the presence of Babesia sensu stricto and Babesia microti-like sp. piroplasms. Infections of Babesia microti-like sp. were found in nearly all locations sampled, often with high prevalence, while Babesia sensu stricto infections had higher prevalence in the Southeastern United States (20–45% prevalence). Co-infections with both Babesia sp. were common. Sequencing of the partial 18S rRNA and cytochrome oxidase subunit 1 (cox1) genes led to the discovery of two new Babesia species, both found in several locations in the eastern and western United States. One novel Babesia sensu stricto sp. was most similar to Babesia gibsoni while the other Babesia species was present in the ‘western piroplasm’ group and was related to Babesia conradae. Phylogenetic analysis of the cox1 sequences indicated possible eastern and western genetic variants for the three Babesia sensu stricto species. Additional analyses are needed to characterize these novel species; however, this study indicates there are now at least four species of piroplasms infecting raccoons in the United States and Canada (Babesia microti-like sp., Babesia lotori, a novel Babesia sensu stricto sp., a novel western Babesia sp.) and a possible fifth species (Babesia sensu stricto) in raccoons in Japan. Keywords: Babesia, Cryptic species, Piroplasms, Raccoons, Tick-borne pathogens