Molecular detection of toxoplasma gondii oocytes in the soil from the public parks of the Arak City, Iran

Soil structure is mainly composed of sand, silt, clay, and organic materials. Organisms can live in the soil. The large number of stray cats in the cities of Iran is a major environmental and health problem. Toxoplasma oocysts are shed with the feces of cats, so soil is known as a potential source of transmission of toxoplasmosis. The aim of this study was to determine the soil contamination with Toxoplasma gondii oocyst in the public parks of the Arak city. Sixty soil samples were collected from 15 main parks of Arak city. Four soil samples from the children's playground, a potting place, around trash bins, and around toilets were taken. Oocyst was isolated from soil by floatation in saturated sucrose. Floating debris was tested by two methods: staining by the modified Ziehl-Neelsen technique and PCR. The target of PCR was the 122 bp fragment of the B1 gene. From 60 soil samples of public parks of Arak city, 8 samples [13%] were suspected to Toxoplasma oocyst contamination in staining smears. Only 3 samples [5%] of 60 samples were positive in PCR. The results showed that the staining method is not a good method to detect oocysts in the soil because the diversity of oocyst in soil is very high and similar in appearance. This study showed soils of public parks in the Arak city were contaminated to oocyst of Toxoplasma. Also molecular method for the detection of parasites in the soil was more suitable than staining method