Prevalence and Comprehensive Molecular Characterization of Sarcocystis glareoli from Brain Samples of Small Mammals Captured in Lithuania.

PURPOSE: The aim of the study was to assess Sarcocystis prevalence in brains of small mammals from Lithuania and to comprehensively characterize their genetic variability. METHODS: Brain samples of 687 small mammals (mice, voles and shrews) from Lithuania were analysed for Sarcocystis spp. using light microscopy and DNA sequence analysis. Parasites isolated were genetically characterised at nuclear 18S rRNA, 28S rRNA, ITS1, ITS2, mitochondrial cox1 and cytb, and apicoplast rpoB. RESULTS: Microscopic and molecular examination revealed the presence of S. glareoli in three rodent species (Apodemus flavicollis, Clethrionomys glareolus and Microtus arvalis), with a total prevalence of 2.6%, (95% CI 1.4–4.4) and in single eulipotyphlan species (Sorex araneus), with a total prevalence of 0.65% (95% CI 0.02–3.6). Among the investigated hosts, the highest 13.0% (95% CI 6.4–22.6) infection rates occurred in C. glareolus. This study constitutes the first documented case of S. glareoli infecting a member of the order Eulipotyphla on a global scale. Additionally, we provide first ITS2, cox1, cytb, and rpoB sequences of S. glareoli. Only minor intraspecific genetic variability was observed in ITS1 and ITS2. Phylogenetic analyses placed S. glareoli in close relation to S. jamaicensis, S. microti, and several undescribed Sarcocystis species. CONCLUSION: The result of the present work is significant for the epidemiology and distinguishment of S. glareoli from genetically similar species and for phylogenetic studies of Sarcocystis spp. with small mammals as their intermediate hosts.