Echinococcosis of animals and humans as a socially dangerous problem in a densely populated subject of the North Caucasus

Abstract

Introduction. Echinococcosis in animals and humans as a zoonotic infestation on the global scale has a tendency to increase the quantitative parameters of morbidity. Among naturally occurring parasitic diseases in animals and humans, human and animal echinococcosis has acquired the status of epizootic, epidemiological, sanitary and hygienic infectious and socially dangerous nosological entity, including in the densely populated North Caucasus region (Karachaevo-Cherkessia Republic). In the south of the Russian Federation with favourable temperature and humidity conditions, echinococcosis invasion occurs in more than 60 species of animals and humans. In addition, echinococcosis in dogs and wild carnivores has also become the main sanitary threat for the regions. In the Russian Federation, the echinococcosis in sheep, goats, buffalo, and cattle in regions with warm and moderate temperatures has resulted in the 1.5-2.0-fold decrease in the survival of livestock and the realization of the biological potential of all types of productivity. Materials and methods. The analysis of animal and population morbidity with echinococcosis in the subject of the Russian Federation (Karachay-Cherkessia Republic) in 2012-2020 was carried out on the base of summarizing the reports of regional divisions of the Federal Service for Supervision in Protection of the Rights of Consumer and Man Wellbeing, veterinary clinics, and sections of the Veterinary Department of the Ministry of Agriculture of the Russian Federation. The diagnostic methods generally accepted in medical and veterinary parasitology (coproscopy, helminthoscopy, native smear method, Demidov and Fülleborn methods) with respect to fecal and soil samples and complete helminthological dissection of animal organs according to K.I. Skryabin (1928) served as the methodological base. The basic epidemiological and epizootological data of the Federal Service for Supervision in Protection of the Rights of Consumer and Man Wellbeing and the Departments of Veterinary Affairs of the RF subject (Karachaevo-Cherkesskaya Republic) concerning the distribution of echinococcosis among animals and humans (frequency index) and the sanitary contamination of soils with eggs of the tenid type, including cestode Echinococcus granulosus were statistically processed using the Biometrics software. Results. Karachay-Cherkessia Republic belongs to the unfavourable regions of the Russian Federation by echinococcosis of flesh-eating and ruminant animals. The occurrence index of echinococcosis in wolves from 2012 to 2020 increased from 38.4% to 68.5%, in domestic dogs - from 73.6% to 100%; jackals - from 46.9% to 90.8%. In the plain zone the index of occurrence of echinococcosis in goats is characterized by an increase from 8.6% to 23.4%; in the foothill zone from 11,7% to 25,2%; in the mountain zone - from 6.9% to 20.6%, which represents an epizootic risk for livestock due to insufficient measures on dogs deworming. In the plain zone from 2012 till 2020 the indices of cystic echinococcosis in sheep also show increase from 10.8% to 26.10%; in the foothill zone from 13.3% to 31.5%; in the mountain zone from 8,5% to 23.2%. In Karachay-Cherkessia from 2012 to 2020 the incidence of cystic echinococcosis in plain, foothill and mountain settlements decreases manifold. The number of people with echinococcosis decreased from 6 to 1 in total (6.0 times), which indicates an improvement of the epidemic situation in the region due to the program-targeted management measures against the dangerous zoonosis, which was based on improving the hygienic and sanitary culture of the population. Soil samples from different infrastructures, taken for the study, in 100% of cases were inseminated with eggs of the tenid type, including cestode Echinococcus granulosus, which indicates a high level of contamination in urban and rural objects. This situation may further lead to the spread of cystic echinococcosis in intermediate hosts, including humans. Data on the contamination in the urban and rural infrastructure of Karachay-Cherkessia by Tenidae eggs were obtained for the first time. Conclusion. The material on population incidence of echinococcosis and in various animals according to materials of supervising bodies and own researches is summarized. The occurrence of cestode eggs in soil has been proved, as the authors cite the results of their own studies, which are given in the text. Karachay-Cherkessia Republic belongs to the unfavourable regions of the Russian Federation for echinococcosis of carnivores and ruminants, which is indicated by a 2.2-3.0-fold gain in the index of infestation due to poor implementation of measures for dehelminthization in dogs. At the same time, the incidence of cystic echinococcosis in the plain, foothill and mountain settlements decreased by multiples. The number of ill people decreased from 6 to 1 (6 times), which indicates an improvement of the epidemic situation due to the program-targeted management of measures to combat zoonosis and improve the sanitary and hygienic culture of the population. At the same time, the soils of urban and rural sites were found to be infested with tenid eggs in 100% of cases. The percentage of soil samples with viable tenid eggs was high and varied in urban soils from 58,7±4,26% to 83,0±6,90%, and in rural soils from 82.4±7.13% to 88.3±7.59%, which can lead to wide spread of echinococcosis in intermediate hosts, including humans. Practical measures to reduce the epidemiological and sanitary and hygienic problems of echinococcosis in animals and humans can be solved only on the base of complete coverage in dog population with deworming treatment using effective means, sanitary permissible regulation of wild carnivores and activation of veterinary surveillance bodies.