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. pseudotuberculosis 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.                            | 
                        
                        
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