Российский паразитологический журнал (Dec 2020)
<i>Echinococcus granulosus</i> Batsch, 1786; Rud., 1801 as a probable sanitary threat in the mountainous zone of the North Caucasus
Abstract
The purpose of the research is studying environmental objects contaminated with Taeniidae eggs, and egg stability and viability in soil and feed supplies in the mountainous zone of the North Caucasus.Materials and methods. The studies were carried out in the mountainous zone of the North Caucasus in 2016–2019 at the laboratory of infective diseases of animals and birds of the Caspian Zonal Research Veterinary Institute. We examined 200 samples of dog feces, 3,600 soil samples and 1,000 samples of different types of food for Taeniidae eggs at altitudinal belts of 1000, 1500, 2000, 2500, 3000 and 3500 m above sea level in winter, spring, summer and autumn using conventional methods. Experiments were also carried out to determine the viability and possible overwintering from November to March of Echinococcus granulosus eggs at an altitude of 1,000, 1,500, 2,000, 2,500, 3,000 and 3,500 m above sea level. In order to study the sanitary state of infrastructure facilities of the mountainous zone for contamination with Taeniidae eggs, we studied 300 soil samples from near-village pastures, distant pastures, rural households, near-shed areas, shelters, near watering stations, along the sides of mountain rivers, and in places of daytime rest of sheep and cattle in pastures using the methods generally accepted in helminthology. We studied possible survival in the winter of Taeniidae eggs in external environment in samples of feces, soil, after-grass, hay, silage and compound feed from November to March. After winter, Taeniidae eggs were examined by coproovoscopy methods. The data were processed by statistical methods according to N.A. Plokhinsky (1978).Results and discussion. It was found that temperature fluctuations of 13.4 to 25.8 ºС in spring and summer seasons in the mountainous zone had a more favorable effect on cestode egg preservation and development. Eggs became invasive in 8–10 days in June and August. The maturation of E. granulosus eggs to the invasive stage was observed in 13 days in September (20.5 ºС), and in 22 days in November (8.3 ºС), which was associated with a decrease in ambient temperature. In dynamics, soil contamination with E. granulosus eggs in the Dagestan mountainous zone in 2016–2019 was characterized by an annual increase in soil contamination with eggs. The soil contamination rate with Taeniidae eggs increased from 63.00% to 88.00% (mean 80.50% of samples). In Dagestan, there is a deterioration in sanitary state of soils of infrastructure facilities as indicated by an increase in Taeniidae eggs in 4–5 g of soil from 7.60±0.40 to 19.30±1.10 eggs (mean 12.30±0.70 eggs). The soil of all studied infrastructure facilities was almost 100% contaminated with Taeniidae eggs. At biological sites, at an altitude of 1,000, 1,500, 2,000, 2,500, 3,000 and 3,500 m above sea level, there were 26.30% 19.84%; 12.55%; 8.0%; 4.99% and 0% of E. granulosus eggs viable in March, respectively. E. granulosus eggs do not survive the winter at an altitude of 3,500 m in March. The study of the possibility of E. granulosus eggs to overwinter showed that the eggs kept in after-grass, silage, hayand compound feed samples during the winter retained viability in the amount of 37.30%, 74.30%, 81.70% and 92.40 % respectively. In case of sanitary requirements violated during grazing, procurement and storage, the aftergrass, silage, hay and compound feed contaminated with Taeniidae eggs are factors for ensuring preservation and viability of invasive elements and continuous implementation of an epizootic process of taeniidosis in populations of ruminants..
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