Molecular evidence and diversity of the spotted-fever group Rickettsia spp. in small mammals from natural, suburban and urban areas of Eastern Slovakia

Abstract

Rickettsiae of the spotted fever group are considered as emerging pathogens; ticks, fleas and mites are known to be their vectors. However, the prevalence and species diversity of rickettsiae in small mammals and the role of these hosts in the circulation of bacteria are much less studied. During 2014-2016, a total of 250 small mammals (Apodemus agrarius, Apodemus flavicollis, Apodemus uralensis, Myodes glareolus, Crocidura leucodon, Crocidura suaveolens, Micromys minutus, Microtus arvalis, Microtus subterraneus, Neomys fodiens and Sorex minutus) were captured in natural, suburban and urban habitats of eastern Slovakia. Ear biopsies of 245 individuals were examined for the presence of SFG rickettsiae by molecular methods. The overall prevalence of Rickettsia spp. in small mammals was 11%. The predominant species, Rickettsia helvetica was confirmed in the striped field mouse (A. agrarius), the yellow-necked mouse (A. flavicollis), the bank vole (M. glareolus) and the common vole (M. arvalis) in natural and suburban habitats, followed by Rickettsia sp. closely related to R. felis identified in A. flavicollis captured in a suburban habitat. Finally, R. slovaca was found in only one yellow-necked mouse (A. flavicollis) captured in a natural habitat, with the sympatric occurrence of Dermacentor marginatus and Dermacentor reticulatus ticks. We assume the presence of R. slovaca especially in sites with the occurrence of Dermacentor spp. All small mammals captured in the urban habitat tested were negative for the presence of rickettsiae. This study brings the first molecular evidence of R. slovaca in a rodent captured in Slovakia. Rickettsia sp. closely related to R. felis was first time detected in A. flavicollis in suburban site of Slovakia. The highest species diversity of rickettsiae was observed in A. flavicollis, and the highest prevalence of bacteria was recorded in M. glareolus. The highest occurrence of rickettsiae-positive small mammals was recorded during the spring and autumn months, May, June and September, respectively. This may be related with the seasonal activity of the tick vectors. This study confirms the long-term persistence of Rickettsia spp. in small mammals in natural and suburban habitats of Slovakia. Some rodent species that have a wider ecological valency may contribute to the maintenance, circulation and dissemination of rickettsiae within and out the natural foci more significantly than those species that have narrower relation to the certain type of habitat.

Keywords: Rickettsia spp.; Rodents; Slovakia; Small mammals; gltA.