Natural infection of the wild canid, Cerdocyon thous, with thepiroplasmid Rangelia vitalii in Brazil

Canine rangeliosis, caused by the piroplasmid protozoon Rangelia vitalii, is currently rec-ognized as a reemerging disease that affects domestic dogs in Brazil. In the present study,piroplasmid infection was searched in wild canids (20 Cerdocyon thous and 4 Lycalopexgymnocercus) in Brazil. Molecular analysis, based on PCR and DNA sequencing of a portionof the 18S rRNA gene, revealed that 30% (6/20) C. thous were infected by R. vitalii. Bloodand bone marrow samples from one of the R. vitalii-infected C. thous were inoculated into adomestic dog, which developed clinical rangeliosis that was confirmed by molecular tests.However, the C. thous donor showed no clinical, hematological or biochemical alterations,even though its R. vitalii infection status was confirmed for at least 80 days. These observations suggest that R. vitalii is not as highly pathogenic for C. thous as it is for domestic dogs. Phylogenetic analysis inferred by the 18S rRNA gene placed R. vitalii embedded inthe clade ‘Babesia sensu stricto’, consisting of a number of species that represent truly thegenus Babesia. It is proposed that the species R. vitalii should be transferred to the genusBabesia. The present study expands our knowledge on the natural history of R. vitalii, suggesting that it might have a natural cycle involving the wild canid C. thous. Further studiesare needed to confirm that C. thous is a natural reservoir of R. vitalii in Brazil