Small mammals as reservoirs and vectors of yersiniosis pathogens (Yersinia enterocolitica and Y. pseudotuberculosis)

Abstract

Yersinia infections are recorded worldwide and sapronotic natural foci of Yersinia enterocolitica and Y. pseudotuberculosis infections also occur in the Crimean Peninsula. Here we studied the distribution and prevalence of pathogenic Yersiniae among small mammals of the Crimean Peninsula based on results of epizootiological monitoring of natural foci infections. Pathogenic Y. enterocolitica were found in 10 species of small mammals, and the average number of infected specimens in the Crimea was 0.11 ± 0.03. The highest prevalence of yersiniosis pathogens was recorded among specimens of M. socialis (4.22 %), M. spicilegus (2.06 %), C. leucodon (1.96 %), S. flavicollis (1.85 %), and S. uralensis (1.33 %). The number of small mammals that are carriers of pathogens of yersinioses varies significantly in different natural zones of the Crimean Peninsula. In the mountain-forest zone, the prevalence of Y. enterocolitica among Micromammalia is 2.94 %, in the foothills it decreases to 0.99 %, in the lowland — to 0.77 % with a lowest value of 0.62 % in steppe areas of the Kerch Peninsula. Results show a decreasing pattern of prevalence of Y. enterocolitica among small mammals from the mountain-forest zone to plain steppe. A reverse trend was revealed for the prevalence of Y. pseudo¬tuberculosis among Micromammalia: 0.03 % in the mountains, 0.17 % in the foothills, and 0.25 % in the steppe. The number of trap-lines with records of Micromammalia having both infections varies from 18.3 % in the foothills to 21.3 % in the mountains and 24.8 % in the steppe zone. The portion of trap-lines with three and more infections is also high (6.7 % in the mountains and foothills and 5.5 % in the steppe). The obtained results show a wide distribution of combined foci in the Crimea. Considering that, in the peninsula, several tick-transmitted and other zoonotic infections (e.g. tick-borne encephalitis and borrelioses, anaplasmosis, ehrlichiosis, Marseilles fever, Q fever, etc.) are widely distributed in the same areas and the pathogens of which are able to reproduce in the same small mammal species as those of yersiniosis and pseudotuberculosis, the real number of combined foci and their diversity in the Crimea could be 3 to 5 times higher.