Study on Soil Contamination With Toxoplasma gondii Oocysts in Eastern Iran

Mahmoodi, Akram; Mousavi, Seyed Mohammad; Tavakoli Kareshk, Amir; Behravan, Mahmoodreza

doi:10.32598/ARI.81.4.3721

Study on Soil Contamination With Toxoplasma gondii Oocysts in Eastern Iran

Document Type : Original Articles

Authors

¹ Infectious Diseases Research Center, Birjand University of Medical Sciences, Birjand, Iran.

² Research Center for Hydatid Disease in Iran, Kerman University of Medical Sciences, Kerman, Iran.

10.32598/ARI.81.4.3721

Abstract

Introduction: Toxoplasma gondii is a common zoonotic protozoan parasite, with felids as definitive hosts that release environmentally resistant oocysts. Soil contamination is a significant transmission pathway for human infection. This study aimed to assess the frequency of T. gondii oocysts in soil samples from Birjand City, Eastern Iran, using concentration and molecular methods, while evaluating seasonal and geographical variations in contamination.
Materials & Methods: In this descriptive cross-sectional study, 254 soil samples (500 g each from a depth of 3-5 cm) were collected from public parks, playgrounds, and urban gardens across Birjand during all four seasons (2024-2025). Samples were processed using the sodium nitrate flotation technique and examined microscopically for oocyst identification. PCR targeting the B1 gene of T. gondii was conducted on all samples.
Results: Of the 254 samples, 23 (9%) were positive for T. gondii oocysts by both microscopic examination and polymerase chain reaction (PCR) confirmation. No significant differences in contamination rates were found between geographical areas (P>0.05). The highest positivity rate was observed in summer, but seasonal variations were not statistically significant (P=0.1).
Conclusion: The findings indicate a notable risk of soil-borne T. gondii infection for humans and animals in Eastern Iran, warranting public health interventions.

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