In the present study, the microscopy and polymerase chain reaction methods were used for detection
and identification of soil contamination by Toxocara eggs in squares, streets, public parks, and rubbish
dumps in Ahvaz, southwestern Iran.
A total of 210 soil samples were collected from different parts of the city and examined by microscopy
and polymerase chain reaction (PCR) methods, following sodium nitrate flotation. Nucleotide sequencing
was performed to confirm the results of the PCR method. Toxocara eggs were found in 64 and 71 soil samples
using the microscopy and PCR methods, respectively. The highest contamination rate was observed
in the central part of Ahvaz (39.5% and 46.5% by the microscopy and PCR methods, respectively). Based
on internal transcribed spacer 2 (ITS2) PCR identification, 28% of the samples were diagnosed as Toxocara
cati and 5.7% as Toxocara canis; no mixed contamination was observed. DNA sequencing of the ITS2 gene
confirmed our findings.
Compared to the conventional microscopic detection following by flotation, used as the gold standard,
the PCR method appears to be rapid and sensitive as well as allows analysis of Toxocara spp. isolated from
soil independent of the stage of egg development. Therefore, the PCR method appears to be a valuable
tool for the diagnosis and differentiation of Toxocara spp. from soil samples in epidemiological studies,
and will help the local health systems in effective prevention and control of diseas
