Journal of Semnan University of Medical Sciences
Image Credit:Koomesh
Outline
Investigation of Soil Contamination with Toxocara Eggs in Public Parks of Semnan Province
Authors
Abstract
Background: Toxocara canis and T. cati are two parasitic nematodes of the genus Toxocara, whose definitive hosts are dogs and cats, respectively. These parasites can cause toxocariasis in humans. The main route of human infection is through contact with or ingestion of embryonated eggs of Toxocara species present in the environment. Soil is considered an important source of transmission, and children, due to their underdeveloped hygiene habits and tendency to play in the soil, are at higher risk of infection. Therefore, assessing soil contamination in environments such as parks and playgrounds is of particular importance.
Objective: To investigate soil contamination in public parks of Semnan Province with Toxocara spp. eggs using both microscopic and molecular methods.
Methods: A total of 43 soil samples were collected from parks located in 10 cities of Semnan Province between May and July 2023. After recording the geographic coordinates of each sampling site, the samples were transferred to the laboratory. The presence of Toxocara eggs was examined using the microscopic zinc sulfate flotation method and a molecular Nested PCR technique.
Results: Among the 43 soil samples examined, 11 samples (25.58%) were found positive by the microscopic method, and 3 samples (6.9%) were positive by the molecular method. Considering the geographic distribution of the sampling sites, Toxocara eggs were detected in soil samples from most parks in Semnan Province.
Conclusion: The results indicate the presence of Toxocara spp. eggs in soils of public parks across Semnan Province. Therefore, public education on disease prevention and control of stray animals in urban areas are essential. Moreover, the higher number of positive results obtained by microscopy compared to the molecular method may be due to the presence of PCR inhibitors such as humic compounds in the soil and the high resistance of Toxocara eggs to DNA extraction processes.
Highlights
References
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Copyright
© 2026, Author(s). This open-access article is available under the Creative Commons Attribution 4.0 (CC BY 4.0) International License (https://creativecommons.org/licenses/by/4.0/), which allows for unrestricted use, distribution, and reproduction in any medium, provided that the original work is properly cited.
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