It is a well-known fact that high biodiversity is related to the health and proper functioning of environment. Recently, the attempts to search the relations between biodiversity and human health are also undertaken. A number of studies demonstrate that people living in undegraded environment are less exposed to the diseases of affluence. However, they are at a higher risk of contracting zoonoses. It is believed that the higher the number of animals, the higher is the number of ticks. Consequently, there is a serious risk of borreliosis and other tick-borne diseases. Such assumption, however, may be erroneous. A number of studies suggest a decreasing prevalence of tick-borne disease pathogens in high-biodiversity areas. In this paper, a promising hypothesis explaining this relation is discussed.