[Reservation forms of plague infectious agent in Tuva natural focus].

Data characterizing the reservation forms of plague infectious agent in Tuva natural focus are presented in the review. Yersinia pestis was shown to persist most of the year in Citellophilus tesquorum altaicus imago --the main carrier, getting into the animal organism only for a short time. An increased ability to aggregate in autumn and accumulate in clumps of C.

[Epizootological assessment of the possibilities of importing plague from Vietnam to Russia].

To assess whether the plague microbe with vectors or carriers can be imported from Vietnam to Russia, the authors consider the specific features of pathogen circulation in this country's biotopes varying in anthropogenic transformation. The idea that there were natural foci of plague in Vietnam dominated until the late 1990s. The small rat Rattus exulans that inhabits open stations and ensures a parasitic contact with the synanthropic representatives of the fauna was considered to be a major carrier.

[Natural foci of plague in India: epizootological characteristics].

In the first half of the 20th century, India was responsible for the incidence of plague in both Asia and the world. The early 21st century was marked by two new epidemic outbreaks of plague (in 2002 and 2004) in this country. The major characteristics of plagues in India, activation of which is a cause of new epidemic outbreaks and necessitates a continuous epizootological monitoring, are analyzed.

[Role of fleas, the principal and secondary plague vectors, in the circulation of the causative agent in Siberian natural foci].

The paper reviews data on the role of fleas as the principal and secondary vectors of infection in the Siberian natural foci of plague. The role of Citellophilus tesquorum as the principal plague vectors in the Transbaikalian and Tuvinian natural foci is shown to be determined by their ecological characteristics (the degree of specificity to the main host, numbers, and natural infection) to a greater extent and by the rate of block formation to a lesser extent. The significance of principal and secondary vectors is estimated in the circulation of the causative agent in the monovectoral (Transbaikalian and Tuvinian) and multivectoral (Gorno-Altai) foci of plagues.