Molecular Speciation of Cyathostomins From Horses In Ireland

Abstract

AbstractCyathostomins are globally important equine parasites, responsible for both chronic and acute pathogenic effects. The occurrence of mixed infections with numerous cyathostomin species hinders our understanding of parasite epidemiology, host-parasite dynamics and species pathogenicity. There have been few studies of cyathostomin species occurring in horses in Ireland, where temperate climatic conditions with year-round rainfall provides suitable conditions for infection of grazing animals with bursate nematodes. Here, we amplified and sequenced the ITS-2 region of adult worms harvested at post-mortem from 11 adult horses between August 2018 and June 2020, and recorded species prevalence and abundance of worms recovered from the caecum, right ventral colon and left dorsal colon. Seasonal distribution, phylogenetic relationships and community composition were also recorded and compared with other relevant studies, including a global meta-analysis. Overall, our results agree with previous research, in that there does not seem to be a major difference in cyathostomin species occurrence in equids in different geographical regions. We confirmed the results of other studies in relation to the difficulties in discriminating betweenCylicostephanus calicatusandCor. coronatuson the basis of ITS-2 sequences. We found a positive correlation between the occurrence ofCyathostomum pateratumandCyc. calicatus(p < 0.01).Cor. coronatus, the most abundant species, was only recovered from horses sampled in autumn. Although this study is limited in terms of sample size, it provides a platform for furthering understanding of the epidemiology and pathogenesis of equine cyathostomin infections in temperate climates.Graphical Abstract