Ecology is a branch of biology that studies the relationship between organisms and their environment. Ecology is divided into three sections: ecology individuals studies of the interaction of animals environment; ecology population - the study of conditions of formation of structure and dynamics of natural groupings of individuals of one species, ecology of communities, or biocenology,studies the relationship of animal ecology and ecology of plants and microorganisms.
Ecology has a close relationship with medicine, especially in terms of developing measures of prevention and control of many infectious and invasive diseases, when you have to take into account the peculiarities of ecology of vectors (see) and carriers of disease, environmental pollution and other
Cm. also Biocenosis, Natural focal diseases).

Ecology (from Greek. oikos - dwelling place and logos - doctrine) - biological science about those relationships of an organism with an environment which cause his survival, development and reproduction. The main objects of the study of ecology - individuals, populations of the same species and communities of different species. Accordingly ecology is divided into three sections - ecology of individuals, E. populations, E. communities.
The environment for medicine that its methods are widely used in the study of the phenomena of parasitism, outbreaks of zoonoses and especially natural focal diseases. Simultaneously ecology serves as the basis for development of measures of struggle against animals-carriers and carriers of pathogens of diseases dangerous to humans.
Thus, the study of the ecology of the species, i.e., their relationships with the environment in different habitats and natural areas, allows to reveal differences relations in different species and one species in different environmental conditions. The latter is of great importance in clarifying the role of individual species in the centers of human diseases.
Population ecology studies the conditions of formation of structure and dynamics of natural groupings of the same species. The most important problem of this section is to study the dynamics of species of populations of animals and factors causing it. It is of great practical importance, allowing to put the forecasts of development of epizootics, and develop the struggle with them. In addition, the study of population dynamics allows to determine the structure of foci, to identify the place of the sustainable conservation of pathogens.
Ecology of communities, or biocenology, binds the ecology of animal ecology of plants, in particular micro-organisms. The object of the study - the Association of interacting populations of different species of plants and animals that live in the same habitat, and the components of the community, or biocenosis (see). The basis of the study of this section of ecology are interspecific relations of animals and plants, predator and prey, parasites and hosts, etc. This topic has special significance for the understanding of the General phenomena of parasitism, and in the study groups of animals or so-called parasitic systems, causing natural focality (see) human diseases.