Sanitary-parasitological condition of the environmental objects of the Astrakhan region

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Introduction. Infectious and parasitic diseases are of great social and economic importance and are currently one of the most pressing health problems [1 – 4]. The annual incidence of helminths in Russia, according to parasitological monitoring, is 1400 cases per 100 thousand population. Almost every person in our country is infested with helminths at least once during his life [5].
one of the main issues of parasitological science is the search for ways to improve the parasitological situation and improve the health of the population from parasitosis [6]. The results of sanitary and parasitological studies create the necessary conditions for effective prevention of parasitic diseases [7].
In connection with the intensification of the development of society, one of the most important problems of our time is the problem of parasitic pollution of urbanized territories by pathogens of helminthiasis of domestic carnivores, primarily dogs. Recently, the total number of dogs in the world has increased significantly and continues to grow. First of all, this applies to stray animals, which are often carriers of various diseases, including helminthiasis [8 – 11]. In Russian cities, the number of stray dogs and cats has also increased significantly. Many helminths that are parasitic in animals serve as a source of human infection, which can also cause environmental contamination and a source of invasion for certain animal species [12].
The external environment is an integral component of the interaction of helminths and their hosts [13]. Of all the objects of the environment, the soil is most often and intensively polluted by pathogens of intestinal parasitic diseases. From contaminated soil, pathogens of parasitic diseases can get on vegetables, fruits, berries, table greens, hands, clothes, and water bodies, which creates conditions for an increased risk of infection of people and animals [14, 15].
It is estimated that more than a billion people worldwide are infested with soil-borne helminths, with the majority occurring in tropical and subtropical countries. Geohelminths, which include ascarids, whipworms and hookworms, are the main parasites that affect humans. These infections most often occur as a result of exposure to faecal-contaminated water, soil, or contaminated food, as well as an increased risk of infection due to the reuse of wastewater and silt in agriculture [16].
thus, according to experts from the united states of america, the total prevalence of soil helminths is 10.4%, of which ascaris lumbricoides is predominant in most cases (8.8%).
For many parasitoses, the main transmission factors are soil and water contaminated with faeces. A special group of parasitoses, infection of which can occur through the soil, are zoonotic invasions, which include toxocarosis, echinococcosis, alveococcosis, hookworm disease, strongyloidosis, etc. [17]. It is proved that chernozems used for horticultural purposes are often a potential source of helminth infestation.
Allowing to establish the ways and factors of transmission of specific infestations, sanitary and parasitological studies of environmental objects are an important part in the system of ensuring the sanitary and epidemiological well-being of the population [18].
The purpose of the study. to study the sanitary and parasitological state of environmental objects of the astrakhan region for 2016-2019.
materials and methods. The study was conducted by students of the Student scientific circle on Infectious and parasitic diseases in the laboratory of the Department of Infectious Diseases and Epidemiology of the Astrakhan State Medical University in 2016-2019. 689 samples were taken from various environmental objects in order to inseminate them with eggs and larvae of helminths. All studies of selected samples of soil, water, fish and flushes from hard surfaces were carried out according to the methodological guidelines [19-21].
Statistical processing of the results was carried out using the Microsoft Office Exel program and biostat Professional 5.8.4. The percentage expression of the data series was determined.

Results and discussion. It was found that out of 689 samples taken and examined from various environmental objects, 114 (16.5%) did not meet sanitary and parasitological standards (Table 1). At the same time, the share of soil samples taken was 554 (80.4%), of which 107 (19.3%) did not meet sanitary and parasitological standards. Live larvae of Strongyloides stercoralis were found in 83 (15%) cases, fertilized eggs of Ascaris lumbricoides were found in 12 (2.1%), Toxocara canis eggs were found in 10 (1.8%), mixed invasions were observed in 1 (0.2%) sample: fertilized eggs of Ascaris lumbricoides + live larvae of Strongyloides stercoralis and in 1 (0.2%) sample – live larvae Strongyloides stercoralis + eggs of Toxocara canis.
Table 1
Samples taken from various environmental objects
in 2016-2019, abs. ( % )
Samples taken from various environmental objects in 2016-2019, abs. (%)

Object The number of samples Does not meet the standards
Soil 554 (80.4) 107 (19.3)
The washings with solid surfaces 126 (18,3) 4 (3,2)
Fish 3 (0,4) 3 (100)
Water 6 (0.9) -
Total 689 (100) 114 (16.5)

Of the 419 soil samples taken within the city of Astrakhan directly from the territory of playgrounds, 353 (63.7%) were from children's sandboxes, while 49 (13.9%) of them did not meet hygienic standards (in 47 (13.3%) samples, live larvae of Strongyloides stercoralis were found, in 2 (0.6%) – fertilized eggs of Ascaris lumbricoides), Table 2.
Table 2
Soil samples taken from various sites
in 2016-2019, abs. (%)
Soil samples taken from various sites in 2016-2019, abs. (%)

Object The number of samples Does not meet the standards
Playgrounds 419 (75,6) 56 (13,4)
Parks 30 (5,4) 11 (36,7)
Squares 25 (4,5) 10 (40)
The territory of the 30 universities (5,4) 15 (50)
Beaches 50 (9) 15 (30)

30 (5.4%) soil samples were collected and examined from the territory of urban parks, of which 11 (36.7%) did not meet hygienic standards. Toxocara canis eggs were found in 10 (33.3%) of them, and live larvae of Strongyloides stercoralis were found in 1 (3.3%).
The share of soil samples taken from the territory of urban squares was 25 (4.5%) samples, of which 10 (40%) samples did not meet hygienic standards. Live larvae of Strongyloides stercoralis were found in all samples.
of the 30 (5.4%) soil samples taken from the sites of higher educational institutions in astrakhan, located almost on the same territory (astrakhan state technical university, astrakhan state university and astrakhan state university of architecture and civil engineering), 15 (50%) did not meet hygienic standards. Fertilized eggs of Ascaris lumbricoides were found in 10 (33.3%) of them, and live larvae of Strongyloides stercoralis were found in 5 (16.7%).
The share of soil samples taken from the territory of urban beaches was 50 (9%) samples, of which 15 (30%) did not meet hygienic standards. Live larvae of Strongyloides stercoralis were found in all samples.
Soil samples taken from the territory of playgrounds of 3 districts: Limansky, Narimanovsky and Kamyzyaksky were studied in the districts of the Astrakhan region.
So, in the Limansky district, 21 (3.8%) soil samples were taken from the territory of playgrounds, of which 3 (14.3%) samples did not meet hygienic standards. In each of them, live larvae of Strongyloides stercoralis, fertilized eggs of Ascaris lumbricoides and mixed invasion (fertilized eggs of Ascaris lumbricoides and live larvae of Strongyloides stercoralis) were found.

Of the 5 (0.9%) soil samples taken in the Narimanov district, 1 (20%) sample did not meet the norm. Live larvae of Strongyloides stercoralis were found in it.
In the Kamyzyak district, 40 (7.2%) soil samples were examined, of which 3 (7.5%) samples were unsatisfactory. In 2 (5%) of them, live larvae of Strongyloides stercoralis were found, in 1 (2.5%) – mixed invasion (live larvae of Strongyloides stercoralis and eggs of Toxocara canis).
Note that the maximum number of soil samples for the study period was selected in 2018 – 300 (61.5%), of which 45 (15%) were unsatisfactory. In 34 (11.4%) of them, live larvae of Strongyloides stercoralis were found, 1 (0.3%) sample – eggs of Toxocara canis and fertilized eggs of Ascaris lumbricoides. in addition, in 2018, the share of soil samples taken from the territory of playgrounds in astrakhan was 245 (81.7%), of which 24 (9.8%) did not meet hygienic standards. Live larvae of Strongyloides stercoralis were found in 23 (9.4%) samples, and fertilized eggs of Ascaris lumbricoides were found in 1 (0.4%).
in previous and subsequent years, the number of soil samples collected and examined was significantly lower. Thus, in 2016, 5 (0.9%) samples were selected and examined, of which 1 (20%) sample contained live larvae of Strongyloides stercoralis. All soil samples were taken from the territory Of playgrounds. A positive finding was noted in a sample taken from the territory of the playground of the Limansky district of the Astrakhan region.
In 2017, 85 (15.3%) soil samples were examined, of which 28 (32.9%) did not meet the norm. Thus, in 26 (30.5%) samples, live larvae of Strongyloides stercoralis were found, in 1 (1.2%) sample – fertilized eggs of Ascaris lumbricoides and in 1 (1.2%) mixed invasion (fertilized eggs of Ascaris lumbricoides and live larvae of Strongyloides stercoralis).
These positive findings were observed in 25 (40.3%) soil samples taken from the territory of playgrounds in Astrakhan: in 24 (38.7%) samples, live larvae of Strongyloides stercoralis were found in 1 (1.6%) – fertilized eggs of Ascaris lumbricoides. fertilized ascaris lumbricoides eggs were found in 2 (11.1%) soil samples taken in the limansky district, mixed invasion (ascaris lumbricoides eggs + strongyloides stercoralis larvae) was found in 1 (5.5%) sample, and live strongyloides stercoralis larvae were found in 1 (20%) sample from the narimanov district.
In 2019, 164 (29.6%) soil samples were examined, of which 33 (20.1%) samples did not meet sanitary and parasitological standards. In 22 (13.4%) samples, live larvae of Strongyloides stercoralis were found, in 10 (6.1%) – fertilized eggs of Ascaris lumbricoides and in 1 (0.6%) – live larvae of Strongyloides stercoralis + eggs of Toxocara canis. In this case, the soil was taken from the territory of playgrounds in Astrakhan and Kamyzyaksky district. At the same time, in the city limits, all soil samples corresponded to the norm. In the Kamyzyak district, 3 (7.5%) unsatisfactory samples were detected. Live larvae of Strongyloides stercoralis were found in 2 (5%) of them, and live larvae of Strongyloides stercoralis + eggs of Toxocara canis were found in 1 (2.5%).
Of the 126 (18.3%) flushes from solid household surfaces (113 (16.4%) ATMs and 13 (1.9%) supermarket handles) carried out in 2017-2018, 4 (8.6%) samples from ATM surfaces did not meet hygienic standards (7.35% of cases found fertilized eggs of Ascaris lumbricoides and 1.25% – eggs of Enterobius vermicularis). In all flushes from supermarket handles, the samples met hygienic standards (Table 3).
Table 3
Samples of flushes from solid household surfaces taken
in 2017-2018, abs. (%)
Samples of flushes from solid household surfaces taken in 2017-2018, abs. (%)

object 2017 2018
total does not meet the standards total does not meet the standards
atms 33 2 (6,1) 80 2 (2,5)
store handles 13 – – –
total 46 (36,5%) 2 (6,1) 80 (63,5) 2 (2,5)

From food products in 2018, 3 (0.4%) samples of fish (herring) purchased in one of the hypermarkets of Astrakhan were studied. Dead larvae of Anisakis simplex were found in the internal organs of all fish samples.
All 6 (0.9%) samples of river water met sanitary and parasitological standards.

Conclusions
1. The sanitary and parasitological state of environmental objects in the Astrakhan region remains very tense, as evidenced by positive findings in soil samples and washouts.
2. The presence of live strongylid larvae and toxocar eggs in the soil indicates that it is contaminated with the feces of invaded animals.
3. The presence of fertilized ascaris eggs in the soil suggests that it is contaminated with the feces of infested people or that these objects are flooded or flooded with sewage.
4. The presence of eggs of ascaris and pinworms on the surfaces of ATMs indicates non-compliance with the rules of personal hygiene of persons infected with ascaris and / or pinworms using these ATMs.
5. The presence of anisacid larvae in the internal organs of fish is not a contraindication for its sale to the public (internal organs of fish are not subject to consumption).

About the authors

Rudolf S. Arakelyuan

Astrakhan State Medical University

Author for correspondence.
Email: rudolf_astrakhan@rambler.ru
ORCID iD: 0000-0001-7549-2925
SPIN-code: 9245-8543

candidate of medical sciences, associate professor

Russian Federation, 121 Bakinskaya str., Astrakhan, 414000

Khalil M. Galimzyanov

Astrakhan State Medical University

Email: rudolf_astrakhan@rambler.ru
ORCID iD: 0000-0002-6263-8814

doctor of medical sciences, professor

Russian Federation, 121 Bakinskaya str., Astrakhan, 414000

Anna E. Maslyaninova

Astrakhan State Medical University

Email: rudolf_astrakhan@rambler.ru
ORCID iD: 0000-0003-0908-950X

Председатель студенческого научного кружка по инфекционным и паразитарным болезням, студентка 6 курса педиатрического факультета

Russian Federation, 121 Bakinskaya str., Astrakhan, 414000

Tatyuna M. Deeva

Astrakhan State Medical University

Email: rudolf_astrakhan@rambler.ru
ORCID iD: 0000-0001-5474-0600

Заместитель председателя студенческого научного кружка по инфекционным и паразитарным болезням, студентка 6 курса лечебного факультета

Russian Federation, 121 Bakinskaya str., Astrakhan, 414000

References

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