Contamination of environmental objects by helminth-protozoan infestations in Astrakhan region. Аnalysis of activities of “Сenter for hygiene and epidemiology in Astrakhan region” for 2011–2020

Objective. To study and analyze the contamination of environmental objects in the Astrakhan Region (by the example of soil, water, and washout samples from solid household surfaces) based on the results of laboratory studies of the Center for Hygiene and Epidemiology in the Astrakhan Region for 2011–2020.

Materials and methods. The work was carried out on the basis of the Laboratory of Bacteriological and Parasitological Research of the Center for Hygiene and Epidemiology in the Astrakhan Region and in the laboratories of the Branches of the Center for Hygiene and Epidemiology in the Astrakhan Region in 2011–2020.

As a whole, during the analyzed period, the laboratory and its branches conducted laboratory studies of 79 742 samples taken from various environmental objects, and 94 495 studies were performed. The number of samples that do not meet the hygiene standards was 1.01 % (806 samples).

Results. The objects of sampling for the study of their parasitic purity were water, soil and wash-out from solid household surfaces.

The share of water samples in the structure of all the studied samples taken from environmental objects was 7.3 % (5858 samples), of which 172 samples were contaminated with pathogens of parasitic diseases, the extent of invasion was 2.9 %.

The structure of positive findings in the water samples was represented by 6 nosological forms of helminths – 88.0 % (154 samples) and 3 nosoforms of protozoa – 12.0 %.

The share of the studied soil samples in the overall structure of sanitary and parasitological studies of the environment was 11.2 % (8895 samples). The number of unsatisfactory samples in the structure of all positive findings revealed during the study of soil, water and washouts during the analyzed period was 70.4 % (625 samples). The total soil contamination for the period of 2011–2020 was 7.0 % (625 samples).

In most cases, helminth eggs and larvae were detected – 99.8 % (624 samples). The proportion of pathogenic protozoan cysts detected in the soil was 0.2 % (1 sample).

In addition to water and soil samples, the washout samples, taken from solid household surfaces were studied – 81.5 % (64989 samples), of which 0.01 % (9 samples) were unsatisfactory.

All positive findings in the washout samples were represented by two nosological forms of helminthiasis: Enterobius vermicularis eggs – 0.012 % (8 samples) and teniid oncospheres – 0.002 (1 sample).

Conclusions. The presence of helminth eggs and cysts of pathogenic intestinal protozoa in the studied soil and water samples indicates contamination of these objects with the feces of infected persons and/or contamination by sewage runoff resulting from various accidents. The presence of toxocara eggs and strongylid larvae in the soil and water indicates contamination of these objects with the feces of infected animals (dogs, cats). The presence of positive findings in wastewater samples indicates poor-quality disinfection of these objects. The presence of contact helminth eggs in the studied samples of washout samples taken from hard surfaces indicates direct contact of infected persons with these samples.