Seroprevalence and Molecular Investigation of Toxoplasmosis among Working Children in Tehran

Background: Toxoplasma gondii is a pathogenic protozoan that causes toxoplasmosis and spreads worldwide. Objectives: This study aimed to investigate the prevalence of toxoplasmosis by serological and molecular methods in working children and a control group in Tehran. Methods: The study participants comprised 460 children aged 7 - 14 years, including 278 working children and 182 age-matched controls. Blood samples were collected, and a serological test was performed to evaluate IgM and IgG antibodies against T. gondii. Peripheral blood mononuclear cells (PBMCs) were isolated from the blood specimens by gradient centrifugation method. Real-time polymerase chain reaction (PCR) was performed using primer B1 on PBMC samples in children’s blood to determine the status of Toxoplasma infection. Results: Seroprevalence of IgG and IgM antibodies against T. gondii was 24.8% and 0.7%, respectively, in working children; however, in the control group, 12.1% and 2.2% had IgG and IgM antibodies against T. gondii, respectively. The mean IgG titer was 160 ± 86.39 IU/mL and 69.36 ± 88 IU/mL for working children and the control group, respectively (P < 0.0001); however, the mean IgM titer was 4.65 ± 3.04 IU/mL and 3.85 ± 4 IU/mL for working children and control group, respectively (P = 0.8187). Real-time PCR results indicated two (0.7%) positive cases among working children and three (1.65%) samples in the control group. The present study showed a significant difference between working children and the control group regarding the frequency of IgG antibodies (P = 0.0012). However, there was no significant difference in the frequency of IgM antibodies in the two mentioned groups. Conclusions: Seroprevalence of IgG antibody against T. gondii was more in working children than in the control group in Tehran. This investigation revealed a significant difference in frequency and titer of IgG antibodies between working children and the control group. More exposure to the soil and contaminated hands before drinking water or food may be considered factors in the development of toxoplasmosis infection in these children.