The role of small rodents in transmission of vector-borne pathogens in Lithuania

Abstract

Small rodents are considered reservoir hosts for vector-borne pathogens. However, there still is a lack of knowledge on the geographical distribution, genetic diversity and the reservoir hosts for these microorganisms in Baltic countries. This study aimed to investigate the prevalence and genetic diversity of vector-borne bacterial pathogens Borrelia spp., Rickettsia spp. and Bartonella spp. in small rodents. Small rodents of 8 species (Apodemus flavicollis, A. agrarius, Mus musculus, Micromys minutus, Myodes glareolus, Microtus oeconomus, M. agrestis and M. arvalis) were captured withlive-traps in different locations of Lithuania during 2013 2016.. DNR was extracted from the spleen samples of small rodents. Different genome regions of pathogens were amplified with subsequent sequencing of fragments obtained during PCR amplification. The overall prevalence of Borrelia spp. in rodent was 25%, Rickettsia spp. - 34.5 % and Bartonella spp. - 23.7%. Borrelia spp. were detected in six small rodent species (M. arvalis, M. agrestis, M. glareolus, A. flavicollis, A. agrarius). The genotyping of ospA gene and sequence analysis of partial 16S (rrsA) 23S (rrlA) ITS region of Borrelia indicated the presence of two Borrelia species: B.afzelii from the Borrelia burgdorferi sensu lato complex, and B.miyamotoi belonging to the relapsing fever group. The sequence of gltA and 17kDa protein coding gene analysis presence Rickettsia helvetica from A. flavicolis, M. minutus, and M. glareolus. Sequence analysis of gltA, rpoB, groEL and ITS region genes of Bartonella isolates demonstrated the presence of Bartonella grahamii, Bartonella taylorii and Bartonella sp. from the Bartonella rochalimae group. Phylogenetic analysis based on each of the targets demonstrated the presence of different B. grahamii and B. taylorii strains in small rodents. The findings of our study demonstrated the importance of small rodents as potential reservoirs of zoonotic pathogens in Lithuania.