Meta-analysis of cyathostomin species-specific prevalence and relative abundance in domestic horses from 1975-2020: Emphasis on geographical region and specimen collection method

Jennifer L. Bellaw, Martin K. Nielsen

Research output: Contribution to journalArticlepeer-review

30 Scopus citations


Background: Cyathostomins infect virtually all horses, and concomitant infections with 10 or more species per horse is standard. Species-specific knowledge is limited, despite potential species bias in development of disease and anthelmintic resistance. This is the first meta-analysis to examine effects of geographical region and cyathostomin collection method on reported composition of cyathostomin communities. Methods: Thirty-seven articles published in English in 1975 or later, in which adults of individual species were systematically enumerated, were included. Seven regions; North America, South America, eastern Europe, western Europe, northern Europe, southern Africa, and Oceania, and three cyathostomin collection methods; (i) standard necropsy recovery from the large intestine, (ii) critical test collection from post-treatment feces and necropsy, and (iii) diagnostic deworming recovery solely from post-treatment feces, were considered. Generalized mixed linear models analyzed the effects of region and collection method on species-specific prevalence and relative abundance. Species richness was analyzed by mixed linear models. Results: Definitively, the most prevalent and relatively abundant species were Cylicocyclus nassatus (prevalence = 93%, relative abundance = 20%), Cylicostephanus (Cys.) longibursatus (93%, 20%), and Cyathostomum catinatum (90%, 16%). A bias toward horses with high infection intensities and cyathostomin collection from feces resulted in North American critical tests and eastern European diagnostic deworming overestimating the species-specific prevalence and underestimating the relative abundance of rare/uncommon species compared to respective intra-regional standard necropsies. North American critical tests underestimated species richness due partially to identification key errors. Inter-regional standard necropsy comparisons yielded some species-specific regional differences, including a significantly higher Cys. longibursatus prevalence and relative abundance in North America (92%, 33%) than in eastern Europe (51%, 7%) (P > 0.0001). Localization of critical tests to North America and diagnostic deworming to Eastern Europe precluded expansive 'region by collection method' interaction analyses. Conclusion: We provide substantial data to inform study design, e.g. effect and study size, for cyathostomin research and highlight necessity for method standardization and raw data accessibility for optimal post-factum comparisons.[Figure not available: see fulltext.]

Original languageEnglish
Article number509
JournalParasites and Vectors
Issue number1
StatePublished - Oct 12 2020

Bibliographical note

Publisher Copyright:
© 2020 The Author(s).


  • Critical test
  • Cyathostomin
  • Diagnostic deworming
  • Necropsy
  • Prevalence
  • Relative abundance

ASJC Scopus subject areas

  • Parasitology
  • Infectious Diseases


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