| Summary: | There has been a significant increase in the number of reported human cryptosporidiosis cases in recent years. The aim of this study is to estimate the prevalence of <i>Cryptosporidium</i> spp. in wild rodents and shrews, and investigate the species and genotype distribution to assess zoonotic risk. Partial 18S rRNA gene nested-PCR reveals that 36.8, 53.9 and 41.9% of mice, voles and shrews are infected with <i>Cryptosporidium</i> species. The highest prevalence occurred in the <i>Microtus agrestis</i> (field vole) and <i>Myodes glareolus</i> (bank vole). Interestingly, bank voles caught in fields were significantly more often <i>Cryptosporidium</i>-positive compared to those caught in forests. The proportion of infected animals increases from over-wintered (spring and summer) to juveniles (autumn) suggesting acquired immunity in older animals. Based on Sanger sequencing and phylogenetic analyses, <i>Apodemus flavicollis</i> (yellow-necked mouse) is commonly infected with zoonotic <i>C. ditrichi</i>. Voles carry multiple different <i>Cryptosporidium</i> sp. and genotypes, some of which are novel. <i>C. andersoni</i>, another zoonotic species, is identified in the <i>Craseomys rufocanus</i> (grey-sided vole). Shrews carry novel shrew genotypes. In conclusion, this study indicates that <i>Cryptosporidium</i> protozoan are present in mouse, vole and shrew populations around Finland and the highest zoonotic risk is associated with <i>C. ditrichi</i> in <i>Apodemus flavicollis</i> and <i>C. andersoni</i> in <i>Craseomys rufocanus</i>. <i>C. parvum</i>, the most common zoonotic species in human infections, was not detected.
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