Molecular method for the semiquantitative identification of gastrointestinal nematodes in domestic ruminants

Standard diagnostic methods currently in use for the identification of helminth infections in ruminants are based on the morphological analysis of immature and adult stages of parasites. This paper describes a method for the semiquantitative identification of nematodes, mainly Trichostrongyloidea , at species-level resolution. The method is based on amplification and fragment analysis followed by minisequencing of the ITS-2 region (internal transcribed spacer 2) of the ribosomal DNA of parasite eggs or larvae. This method allows for the identification of seven genera ( Chabertia, Cooperia , Haemonchus , Oesophagostomum , Ostertagia , Teladorsagia , and Trichostrongylus ) and 12 species ( Chabertia ovina , Cooperia curticei , Cooperia punctata , Cooperia oncophora/Cooperia surnabada , Haemonchus contortus , Haemonchus placei , Haemonchus longistipes , Oesophagostomum asperum , Oesophagostomum radiatum , Ostertagia ostertagi , Trichostrongylus axei , and Trichostrongylus colubriformis ) of infectious nematodes of domestic ruminants. The concordance between the morphological and molecular analyses in the detection of genera ranged from 0.84 to 0.99, suggesting the proposed detection method is specific, semiquantitative, less laborious, and highly cost-efficient.