The relationship between transmission of infectious diseases and small mammal population dynamics in natural populations of the Yenisei ridge

Interrelations between the dynamics of populations of small mammals and percent of the infected animals was investigated in selections from local populations in harvest areas of the coniferous forests of the Yenisei ridge. Previously, it was found that for normal spleen its index does not exceed 5 ‰. Therefore, it was considered infected individuals who have discovered exceeding this threshold. It was assumed that infectious and invasion diseases in the district of collection of materials is a basic factor, regulative a numbers. It was found that the greatest degree of contamination of infectious diseases is typical for many species groups of the forest (Myodes) and gray (Microtus) voles, lesser in shrews of the genus Sorex. These two groups showed a strong, statistically significant relationship between the dynamic of number and variation of percent of the infected animals. It is educed that the fluctuations in the number and proportion of infected voles synchronized in dark coniferous forests. On the cutting areas of different age, they take place asynchronously and with a delay as compared to base-line biotopes. Synchronization of increase of number of small mammals with morbidity is explained by the increase of frequency of contacts, both between animals at all and animals infected by materials – excrements, food bits and pieces, external parasites. The asynchronicity of dynamic of number and infection for harvest areas is explained in that the process of distribution of infections in harvest areas takes place after increases in animals number and subsequent migrations of patients of animals and moving through cutting areas. This means that the base-line forests are a source distribution of zoonotic infections in the populations of small mammals. For shrews the increase of part of the infected animals took place synchronously with dynamic of number in this group in all types of biotopes. On that basis, supposition about specificity of factor, defiant the increase of spleen for shrews is done.