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

Abstract

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 (<i>Procyon lotor</i>), <i>Babesia lotori</i> (<i>Babesia</i> sensu stricto clade) and a species related to <i>Babesia microti</i> (called <i>B. microti</i>-like sp.). The goal of this study was to investigate prevalence, distribution, and diversity of <i>Babesia</i> in raccoons. We tested raccoons from selected regions in the United States and Canada for the presence of <i>Babesia</i> sensu stricto and <i>Babesia microti</i>-like sp. piroplasms. Infections of <i>Babesia microti</i>-like sp. were found in nearly all locations sampled, often with high prevalence, while <i>Babesia</i> sensu stricto infections had higher prevalence in the Southeastern United States (20-45% prevalence). Co-infections with both <i>Babesia</i> sp. were common. Sequencing of the partial 18S rRNA and cytochrome oxidase subunit 1 (<i>cox1</i>) genes led to the discovery of two new <i>Babesia</i> species, both found in several locations in the eastern and western United States. One novel <i>Babesia</i> sensu stricto sp. was most similar to <i>Babesia gibsoni</i> while the other <i>Babesia</i> species was present in the 'western piroplasm' group and was related to <i>Babesia conradae</i>. Phylogenetic analysis of the <i>cox1</i> sequences indicated possible eastern and western genetic variants for the three <i>Babesia</i> 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 (<i>Babesia microti</i>-like sp., <i>Babesia lotori,</i> a novel <i>Babesia</i> sensu stricto sp., a novel western <i>Babesia</i> sp.) and a possible fifth species (<i>Babesia</i> sensu stricto) in raccoons in Japan.