A review of Eimeria infections in horses and other equids.
Abstract: There is considerable confusion concerning validity of Eimeria species in equids, and endogenous developmental stages and pathogenicity of equid Eimeria. This paper summarizes worldwide information on history, structure, life cycle, pathogenicity, prevalence, epidemiology, and diagnosis of Eimeria infections in equids. The following conclusions were drawn. Although three species of Eimeria; E. solipedum, E. uninugulata, and E. leuckarti were named from horses, only E. leuckarti is a valid species infecting equids, including horses, donkeys and zebra. We consider E. solipedum, E. uninugulata and Isospora sp.as spurious/contaminants with coccidia from other hosts. E. leuckarti oocysts are distinctive, dark brown and up to 94 μm long and up to 79 μm wide. Its gametogonic stages and oocysts are present in the lamina propria of small intestines. In equids naturally infected with E. leuckarti, only sexual stages have been confirmed. In most of the approximately 50 cases of histologically diagnosed cases of E. leuckarti infection, this infection was considered coincidental or of no clinical relevance. However, in some cases E. leuckarti was considered pathogenic, causing diarrhea and enteritis. The prepatent period is long, 30-37 days or more in experimentally infected equids. Natural infections have been found in 4 week-old foals, indicating that foals can become infected on the day of birth. The number of oocysts excreted is not correlated with clinical signs.
Published by Elsevier B.V.
Publication Date: 2018-04-22 PubMed ID: 29887031DOI: 10.1016/j.vetpar.2018.04.010Google Scholar: Lookup
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Summary
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The research article is a comprehensive review of Eimeria infections in horses and other equids, including the species validity, developmental stages, pathogenicity, prevalence, epidemiology, and diagnosis.
Discussion on Eimeria Species Validity
- The paper discusses the validity of different Eimeria species in equids. It concludes that of the three species named originating from horses (E. solipedum, E. uninugulata, E. leuckarti), only E. leuckarti is a valid species that infects equids, including horses, donkeys and zebra.
- Other species, E. solipedum, E. uninugulata, and Isospora sp. are considered to be spurious/contaminants mixed with coccidia from other hosts.
Characteristics of E. leuckarti
- The research describes the characteristic features of E. leuckarti. It states that this species has distinctively dark brown oocysts that can be up to 94 μm long and 79 μm wide.
- It’s mentioned that the gametogonic stages and oocysts of E. leuckarti are present in the lamina propria of the small intestines of the infected hosts.
- In natural E. leuckarti infections, only sexual stages have been confirmed.
Pathogenicity of E. leuckarti
- The paper cites around 50 histologically diagnosed cases of E. Leuckarti infection, where in most cases the infection was considered coincidental or clinically irrelevant.
- However, there are instances where the infection was pathogenic, leading to diseases such as diarrhea and enteritis.
Epidemiology and Infection Stages
- The prepatent period (the time from infection to the detectability of the pathogen) of E. leuckarti is stated to be quite long, ranging from 30 to 37 days or more in experimentally infected equids.
- The research also points out that natural infections have been found in foals as young as 4 weeks, indicating that equids can become infected from the day they are born.
- Interestingly, the paper notes that the number of oocysts excreted by the host organism does not correlate directly with the clinical signs i.e., apparent symptoms of the disease caused by the pathogen are not proportionate to the number of oocysts expelled.
Cite This Article
APA
Dubey JP, Bauer C.
(2018).
A review of Eimeria infections in horses and other equids.
Vet Parasitol, 256, 58-70.
https://doi.org/10.1016/j.vetpar.2018.04.010 Publication
Researcher Affiliations
- United States Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Animal Parasitic Diseases Laboratory, Beltsville, MD, 20705-2350, USA. Electronic address: jitender.dubey@ars.usda.gov.
- Institute of Parasitology, Justus Liebig University Giessen, Schubertstrasse 81, 35392 Giessen, Germany.
MeSH Terms
- Animals
- Coccidiosis / epidemiology
- Coccidiosis / transmission
- Coccidiosis / veterinary
- Eimeria / physiology
- Equidae
- Horse Diseases / epidemiology
- Horse Diseases / transmission
- Horses
Citations
This article has been cited 12 times.- Fang S, Shi Y, Wang P, Guan C, Gu X, Guan L, Cui P, Suo X. Study on the pathogenicity, immunogenicity, endogenous development and drug sensitivity of Eimeria kongi. Front Vet Sci 2023;10:1134193.
- Ysea MAV, Umaña MC, Fuentes SP, Campos IV, Carmona MC. Standardization of molecular techniques for the detection and characterization of intestinal protozoa and other pathogens in humans. J Venom Anim Toxins Incl Trop Dis 2022;28:e20210099.
- Hostetter JM, Uzal FA. Gastrointestinal biopsy in the horse: overview of collection, interpretation, and applications. J Vet Diagn Invest 2022 May;34(3):376-388.
- Kopper JJ, Willette JA, Kogan CJ, Seguin A, Bolin SR, Schott HC 2nd. Detection of pathogens in blood or feces of adult horses with enteric disease and association with outcome of colitis. J Vet Intern Med 2021 Sep;35(5):2465-2472.
- Stout AE, Hofmar-Glennon HG, André NM, Goodman LB, Anderson RR, Mitchell PK, Thompson BS, Lejeune M, Whittaker GR, Goodrich EL. Infectious disease surveillance of apparently healthy horses at a multi-day show using a novel nanoscale real-time PCR panel. J Vet Diagn Invest 2021 Jan;33(1):80-86.
- Reddy PRK, Yasaswini D, Reddy PPR, Zeineldin M, Adegbeye MJ, Hyder I. Applications, challenges, and strategies in the use of nanoparticles as feed additives in equine nutrition. Vet World 2020 Aug;13(8):1685-1696.
- Blake DP, Worthing K, Jenkins MC. Exploring Eimeria Genomes to Understand Population Biology: Recent Progress and Future Opportunities. Genes (Basel) 2020 Sep 21;11(9).
- Ullah A, Geng M, Chen W, Zhu Q, Shi L, Zhang X, Akhtar MF, Wang C, Khan MZ. Effect of Parasitic Infections on Hematological Profile, Reproductive and Productive Performance in Equines. Animals (Basel) 2025 Nov 14;15(22).
- Porter MM, Davis DJ, McAdams ZL, Townsend KS, Martin LM, Wilhite C, Johnson PJ, Ericsson AC. Alterations in the Microbiome of Horses Affected with Fecal Water Syndrome. Vet Sci 2025 Jul 31;12(8).
- Muñoz-Caro T, Gavilán P, Villanueva J, Oberg C, Herrera C, Fonseca-Salamanca F, Hidalgo A. Endoparasitism and risk factors in horses from ethnic communities in Andean areas of southern Chile. Trop Anim Health Prod 2024 Sep 25;56(8):281.
- Gorji FF, Sadr S, Borji H. Epidemiological study on equine coccidiosis in North and Northeast of Iran. Vet Med Sci 2023 Sep;9(5):2038-2041.
- Sazmand A, Bahari A, Papi S, Otranto D. Parasitic diseases of equids in Iran (1931-2020): a literature review. Parasit Vectors 2020 Nov 19;13(1):586.
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