Molecular Identification and Genotyping of Toxoplasma Gondii in Blood and CSF Samples of Children with Immunodeficiency in Ahvaz, Southwest of Iran

Background: Accurate and effective diagnosis of Toxoplasma gondii (T. gondii) infection can make a significant contribution to the control and prevention of the infection, especially in high-risk individuals. Today, polymerase chain reaction (PCR) is frequently applied for the detection of the infection. Objectives: The aim of this study was to evaluate the frequency and genotyping of T. gondii in blood and CSF samples of children with immunodeficiency. Methods: In the current descriptive cross-sectional study, a total of 170 blood samples and 170 cerebrospinal fluid (CSF) samples were randomly taken from 170 children with immunodeficiency. Firstly, the samples were evaluated using the polymerase chain reaction (PCR) method by targeting the RE gene, and then, positive samples were examined by the nested-PCR method, based on the SAG2 genomic target. For genotyping, PCR-restriction fragment length polymorphism (RFLP) assay was by the Hha I and Sau3A I restriction endonucleases. Results: From 340 samples, 23 (seven blood samples and 16 CSF samples) were detected positive by the PCR method. Of 16 CSF samples, all cases were found positive by the nested-PCR method, while all blood samples were negative. After genotyping CSF samples, T. gondii type II was found in 15 samples and one sample was a mix of both types II and III. Conclusions: The findings indicated that the RE target can be considered as a sensitive method for the diagnosis of toxoplasmosis in the CSF samples, especially in children with immunodeficiency. In addition, this study showed that genotype II was the prevailing genotype in the patients.