Nested PCR for the detection of Taenia solium DNA in stool samples

The traditional parasitological method to diagnose taeniasis is the microscopic observation of eggs in stool samples. However, this method does not allow differentiation between Taenia saginata and Taenia solium. This aim of this study was to achieve the detection of T. solium DNA by polymerase chain reaction (PCR) and to evaluate the cross-reaction with other species of the genus Taenia and other intestinal parasites. DNA was extracted from adult T. solium cestodes by cryolysis in liquid nitrogen and with the DNA stool extraction kit from Qiagen. The detection limit of the test was evaluated by DNA dilutions in water and in stool samples. DNA was extracted from proglottids of T. saginata and T. crassiceps and from stool samples containing other intestinal parasites using ethanol treatment, alkaline lysis, and the DNA stool extraction kit. Nested PCR was used to amplify a previously described fragment of the Tso31 gene, and the PCR products were analyzed by electrophoresis in 2% agarose gels followed by staining with GelRed. The nested PCR of the Tso31 gene allowed the detection of T. solium DNA in stool samples with a detection limit of 20 pg of parasite DNA. PCR showed no cross-reaction with T. saginata, T. crassiceps, or other intestinal parasites of public health importance in Colombia.