Molecular characterization of Strongylida infecting goats and sheep in northeastern Brazil using cytochrome-c oxidase subunit I partial sequencing.

Strongylida parasitizes goats and sheep; increasing resistance to anthelmintics demands species characterization. This study aims to identify Strongylida of goats and sheep in northeastern Brazil, assessing genetic diversity. Seventeen specimens of Ovis aries and 25 of Capra hircus were studied; DNA was obtained from eggs shed in ruminants' feces. A ∼ 700 bp fragment of cytochrome c oxidase subunit 1 (cox1) was PCR-amplified and sequenced; a computational species delimitation analysis was performed; evolutionary significant units (ESUs) were defined using Poisson Tree Process (PTP) and multi-rate Poisson Tree Process (mPTP). Concerning Oesophagostomum, 2 sequences were Oesophagostomum columbianum (2 haplotypes) and 3 were from other species with no cox1 sequences described. This unidentified ESU (3 haplotypes; HD ± SD = 1.000 ± 0.272) was delimited by the PTP and mPTP algorithms, distant 74 mutational steps away from O. columbianum. Trichostrongylus colubriformis (n = 16; 15 haplotypes; haplotype diversity [HD] ± standard deviation [SD] = 0.991 ± 0.025) and Haemonchus contortus (n = 5; 5 haplotypes; HD ± SD = 1.000 ± 0.126) were also characterized. The helminth fauna of small ruminants is genetically diverse and can be monitored before slaughter. Multilocus genetic studies including nuclear targets should be performed to gain a clearer understanding of this diversity.