Detection of Toxoplasma gondii DNA by PCR in blood samples collected from pregnant Saudi women from the Aseer region, Saudi Arabia

BACKGROUND AND OBJECTIVES: Toxoplasmosis, caused by Toxoplasma gondii, is diagnosed mainly by serological methods that are hindered by insufficient sensitivity. When it fails, it becomes necessary to rely on either direct detection of the parasite or DNA detection by polymerase chain reaction (PCR). We aimed to establish molecular tools for toxoplasmosis research in the country by using PCR targeting the B1 gene and compare it with ELISA results. DESIGN AND SETTING: Conducted at the College of Science, King Khalid University, Abha, Saudi Arabia between January 2009 and April 2010 on Saudi pregnant women attending three major hospitals in the Aseer region. PATIENTS AND METHODS: Peripheral blood samples (n=137) were collected from patients. DNA was extracted and the B1 T gondii gene was amplified by PCR. The amplicons were visualized and sequenced, and the results were analyzed. For comparison, sera were tested for anti-T gondii IgG and IgM by enzyme-linked immunosorbent assay (ELISA). RESULTS: Of the 137 samples tested, the B1 gene could be amplified in 56 cases (41%) by PCR. DNA sequencing confirmed these results. IgM-ELISA assay detected 9 (6.5%) of these cases. The results of immunoglobulin G detection were positive in 53 (38.6%) of the patients. CONCLUSION: The present study showed the need for PCR as a confirmatory assay in addition to serological assays to detect recent infection. We recommend national implementation of these molecular diagnostic tools.