Ticks of genus Ixodidae: bioecological mechanisms of adaptation to environmental conditions, medical and epidemiological significance

Abstract

Considering the geographical position of Ukraine, which is located on the border of several physical and geographical zones, the country has a significant variety of parasitic invertebrates and requires constant monitoring in the current integration conditions. Nowadays climatic changes and anthropogenic effect have an impact on ecosystems organization and cause the incidence of transmissible diseases, including tick-borne infections. In order to prevent the spread of pathogens, there is a necessity to analyze modern data of Ixodidae genus ticks, as components of natural and focal humans and animals diseases, their ecological features, behavioral responses, features of biotopic spread, biological patterns, their epidemiological significance. Our review analysis revealed that all stages of tick development depend on three major natural factors: temperature, humidity, duration of the photoperiod, and the presence of a host. Particularly important is the combination of the first two factors that determines the occurrence of two peaks of the number of ticks in April - May and in August – September, the last is less extended. At this time of year the nymphs and imago density increases and their infectious agents rate is increased too. The study of the epidemiological condition proves the fact that nymphs and imago of I. ricinus are equally infected with the most common pathogens of infections: Borrelia burgdorferi sensu lato (sl) and Borrelia miyamotoi, rickettsiae bacteria (Anaplasma phagocytophilum), flaviviruses (tick-borne encephalitis virus and deer tick virus) and the protozoans (Babesia microti, Babesia duncani, Babesia divergens and Babesia venatorum). Often there is a different combination of these pathogens in the one tick. The infectious agents rate have an impact on the ticks behavior differences in the feeding duration, increasing ticks bites frequency, decreasing of blood feeding, and a prolongation of the life cycle. Therefore within the transboundary territories the urgent control of agents and vectors of infectious and invasive animals and humans diseases is required, studying changes of migrant thermophilic species habitats geography, and systematic measures for the prevention of parasites implementation is needed.