Nematode Toxocara canis as a Probable Epidemic, Sanitary and Hygienic Threat to Public Health in the Southern Region of the Russian Federation

Abstract

Introduction: According to the World Health Organization, Toxocara canis, a nematode in the order Ascarididia, is an epidemic and epizootic risk factor for humans and animals around the world and in the Russian Federation. Human toxocariasis is one of the commonest parasitic zoonoses with up to 900 million incident cases registered annually in different age and social groups of the population and a global public health problem of our time. Objective: To study the nematode Toxocara canis (Werner, 1782) as a health risk factor for the population of southern regions the Russian Federation. Materials and methods: We estimated the incidence of larval toxocariasis in the population of 10 districts and two cities of Karachay-Cherkessia based on the results of enzyme immunoassay of blood samples of 6,000 people in 2019–2022. The Tiascar diagnostic test kit (2017) was applied showing toxocariasis for the antibody titer ≥ 1:800 and infestation with Toxocara larvae for those of 1:200 and 1:400. The stool ova and parasite test was used to study 600 dog stool samples from the study areas. In addition, 1,200 soil samples were tested for the presence of Toxocara canis eggs. Results: We established that the incidence rate of larval toxocariasis in the population of 10 districts and two cities of Karachay-Cherkessia varied from 2.00 to 5.40 %. Toxocara canis larvae were not found in human feces, since humans are a biological dead end for this species of worms. Toxocara canis infestation rates in feces of dogs ranged from 2.7 ± 0.4 to 6.9 ± 0.8 eggs/g, potentially accounting for a high level of soil contamination with eggs. The current epidemic situation of human toxocariasis in the Karachay-Cherkess Republic is relatively favorable owing to planned preventive measures. Yet, this constituent entity is at risk of the disease in the future since the number of children, adults and migrants with larval toxocariasis shows a dynamic growth throughout the year. Conclusion: Incidence rates of larval toxocariasis in the child population and migrants demonstrate a 2.74–2.78-fold increase during the year. Toxocara canis eggs contaminate 46 to 94 % of soils in different areas of the republic posing high risks of larval toxocariasis for the local population. In terms of canine toxocariasis, the Karachay-Cherkess Republic can be attributed to disadvantaged territories of the North Caucasian Federal District.