PCR-RFLP analysis of the ITS2 gene. PCR products were visualized on a 3.0% agarose gel. Lane M: 50 bp DNA ladder; Lanes P1–P3: PCR products of Trichostrongylus axei, a mixed infection of T. axei and T. colubriformis, and T. colubriformis, respectively, following digestion with HinfI. Lanes 1–9: PCR products from human or livestock stool samples digested with HinfI. Lane N: negative control (nuclease-free water).