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.

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Published in Parasites & Vectors, v. 13, issue 1, article no. 509.

© The Author(s) 2020

This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (https://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data.

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13071_2020_4396_MOESM1_ESM.xlsx (18 kB)
Additional file 1: Table S1. Publication and dataset demographics.

13071_2020_4396_MOESM2_ESM.xlsx (22 kB)
Additional file 2: Table S2. Pairwise comparisons of species prevalence (%) by region for 35 cyathostomin species within seven regions across 38 publications, 49 datasets, and 1592 hosts.

13071_2020_4396_MOESM3_ESM.xlsx (20 kB)
Additional file 3: Table S3. Pairwise comparisons of species relative abundance (%) by region for 35 Cyathostominae species within five regions across 29 publications, 35 datasets, and 1217 equine hosts examined.

13071_2020_4396_MOESM4_ESM.xlsx (15 kB)
Additional file 4: Table S4. Pairwise comparisons of species prevalence (%) by specimen collection method for 35 cyathostomin species for three methods across 49 datasets.

13071_2020_4396_MOESM5_ESM.xlsx (16 kB)
Additional file 5: Table S5. Pairwise comparisons of species relative abundance (%) by specimen collection method for 35 cyathostomin species for three methods across 35 datasets.

13071_2020_4396_MOESM6_ESM.xlsx (115 kB)
Additional file 6: Dataset S1. Complete data set from this study.