High Throughput Molecular Identification of Ruminant Gastrointestinal Nematodes

Strongylid nematodes are important parasites of domestic ruminants and are responsible for significant economic losses in livestock in tropical and temperate regions. Considering the different degrees of prolificacy and pathogenicity of these nematodes, it is necessary to diagnose those present in each animal for a sustainable parasite control. However, traditional techniques to identify this parasites based on microscopy are laborious, time-consuming and have limited scalability. In this context, molecular diagnostic methods are recommended due to its high sensitivity, specificity and potential for automation. The nuclear DNA ITS-2 (Internal Transcribed Spacer 2) region is well conserved among closely related species and its analysis is applicable in taxonomic studies. The aim of this study was to develop and standardize a high throughput molecular method for the identification of parasitic nematodes of ruminants. Adult worms of the six most prevalent genera in Brazil were morphologically identified and its ITS- 2 region were sequenced. Given the abundance of InDel mutations in ITS-2 region, it was possible to develop a method to identify, by fragment analysis, the nematode genera present in a given sample. The method was adjusted to use capillary electrophoresis in an automated sequencer. The presence of the genera Haemonchus, Cooperia and Ostertagia could be detected in the DNA extracted from faecal eggs samples. Associated with studies on biology and epidemiology of parasites it is possible to use these tools to build effective programs of control to encourage rational use of antiparasitic drugs.