Sanitary parasitological study of the contamination of environmental objects as factors of parasitosis transmission is an important element of sanitary and hygienic monitoring. Using sanitary-parasitological methods of research of environmental objects in 2018, wastewater and its sediments, soil and water of open surface water bodies as the main factors of parasitosis transmission were studied in the territory of the Rostov region and the Republic of Adygea. Screening works were carried out to indicate 137 objects of the surrounding environment that the parasitosis pathogens infected. Extensive and intensive indicators of the contamination of objects with the ascertained viability of the identified parasitic pathogens were determined. Wastewater and its sediments turned out to be the most epidemiologically significant objects, as evidenced by the level of contamination of these substrates with parasitic pathogens and to a greater degree the share of viable helminth eggs detected among them. The spectrum of parasitic pathogens detected in both territories in sewage and sediments was as follows: tokocar eggs (more than 50%), ascaris eggs, pinworms, taeniid oncospheres, ankylostomid eggs, dicrocelium, diphyllobotriid. The soil remains one of the main components of the environment, of great importance in the spread of parasitic invasions. In the studied areas, the ovogram of detected parasitic pathogens in the soil was almost identical: eggs of ascaris, tokocar, pinworms, etc. In addition, the maximum epidemiological significance of the soil was established for geo-and contact helminth infections in respect of the territories of residential areas of settlements, pre-school institutions. The investigated water samples of open surface reservoirs contained only non-viable helminth eggs with low contamination intensity (1–2 specimens / 25 l.).

Parasitic contamination of the soil of some territories of the south of Russia was studied for the presence of eggs and larvae of helminths and cysts of pathogenic intestinal protozoa. The soil is still a potential hazard as a risk factor in the infection of the population with geohelminths. Thus, in the Rostov region, the specific weight of the selected soil samples for the period from 2016 to 2020 was 28.2%, of which 25.5% were positive. In the Republic of Adygea, the specific weight of the selected soil samples for the same period was 59.5%, positive – 30.6%. In the KarachayCherkess Republic – 53.8%, positive – 61.9%. The results of the conducted sanitary and parasitological studies of the soil showed that the share of positive samples in various regions of the south of Russia ranged from 20.5% in the Rostov region to 83.3% in the territory of the Karachay-Cherkess Republic. Among all identified helminth eggs, for Toxocara spp. eggs. In all the studied territories, it was 2–3, and sometimes 5 times higher than the eggs of other helminth species detected in the soil. A fairly large number of Strongyloides spp. larvae were also found, mainly in the Republic of Karachay-Cherkessia. According to this, the main role in soil contamination in the south of Russia belongs to animals.

Ascariasis is a significant public health problem. More than a quarter of the world's population is at risk of infection with soil-borne parasites, and Ascaris lumbricoides is the main type of geohelminthiasis that infects people and affects the population of all countries to some extent. The study is aimed at monitoring ascariasis in the South of Russia, including determining a risk of infecting the population. The analysis of the incidence of ascariasis was performed based on official statistics "On the incidence of protozoans and helminthiasis in the population of the Russian Federation". Over the past 5 years, a serological screening of 2600 samples of blood serum of conditionally healthy residents of the South of Russia was conducted at the premises of the Rostov Scientific Research Institute of Microbiology and Parasitology of the Rospotrebnadzor. Over the same period, more than 7,500 parasitological studies of environmental objects (waste water and its sediments, soil, sand, and surface water) were conducted. A significant proportion of seropositive individuals, as well as the evidence of ascarid eggs detected in environmental objects indicate that the potential risk of infection of the South of Russia population with ascariasis remains. Additionally, the obtained results indicate the need to continue monitoring ascariasis. Further research will provide a more complete picture of the current epidemiological situation on ascariasis and its spread in the South of Russia.

We analyzed data reflected in the records of the epidemiological screening of cases with echinococcosis in 2019 in some constituent entities of the Russian Federation. It was noted that both rural people and urban residents suffered from the disease equally, while women suffered a little more than men (54.4%). It is found that the most common localization of echinococcal cysts, both in men and women, is the liver (79.5%), and the lesion of the lungs caused by echinococcal cysts (9.1) is in the second place. We presented multiple localization of echinococcal cysts affecting several organs simultaneously to a lesser extent. Two cases of hydatidosis and two cases of multilocular hydatid cyst in the liver were accompanied by a fatal outcome. In some territories, alveococcosis was diagnosed in 14 (8.75%) cases. Contacts with dogs, work on livestock farms, caring for pets, picking wild berries or mushrooms in the forest and eating them without thermal treatment, use of raw river water in housekeeping, eating unwashed vegetables and berries, activities in natural environment, hunting and dressing of wild animals, or failure to observe the rules of personal hygiene have great importance in the spread of this disease among the population, according to epidemiological records.

In the structure of parasitic diseases, helminthiasis traditionally accounts for about 90%. Among them, a special role belongs to larval or tissue helminthiasis. In order to further predict the level of endemic helminthiases in specific administrative territories and develop appropriate proposals for planning and implementing preventive and antiepidemic measures, an analysis of the incidence of larval helminthiases in the population was carried out. The data of official statistics (information on infectious and parasitic diseases – form No. 2) on the incidence of larval helminthiases in the period 2016– 2020, as well as maps of epidemiological survey of cases of echinococcosis, trichinosis, toxocariasis and dirofilariasis, received by the Reference Center by monitoring of larval helminthiases, functioning on the basis of the FBSI "Rostov Research Institute of Microbiology and Parasitology" of Rospotrebnadzor. It is noted that the most unfavorable administrative territories in terms of the incidence of larval helminthiases are currently: echinococcosis – the territories of the North Caucasus, Volga and Ural federal districts; toxocariasis – the territories of the Ural and Siberian federal districts, trichinosis – the territories of the Siberian and Far Eastern federal districts. Dirofilariasis was recorded more often in the territories of the Southern and Volga federal districts.