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Infection dynamics of Theileria equi and Theileria haneyi, a newly discovered apicomplexan of the horse.
Abstract: Theileria equi infection, exotic to the United States has reemerged through intravenous (iatrogenic) and tick-borne transmission. Surveillance at the US-Mexico border identified a new species, Theileria haneyi, (T. haneyi) (EP = Eagle Pass, Texas) which warranted additional investigation due to inability to detect by PCR targeting of T. equi ema-1 and EMA-1-cELISA validated for T. equi. Infection dynamics of T. haneyi were evaluated, including ability to superinfect in the presence of T. equi-Texas (T. equi), the isolate responsible for the reemergence of T. equi in the U S. Experimental infection with T. equi or T. haneyi revealed minimal clinical disease however, T. equi infection led to significantly greater neutropenia. Comparison of time to antibody detection following inoculation revealed significantly greater time to detectable anti-T. haneyi antibody (26.67 days post-inoculation (DPI)) than T. equi (11.67 DPI). Regardless of initial infection with either T. equi or T. haneyi, superinfection was established. Comparative analysis of antibody responses from a splenectomized horse infected with T. haneyi to that of a spleen intact horse infected with T. equi revealed a different antibody binding profile to T. haneyi, T. equi and T. equi merozoite antigen and limited shared antigen/cross-reactive antibody(s). Affinity purified T. equi EMA-1 and EMA-2 from T. equi were shown as targets for horse antibodies against T. haneyi. Data presented here show (1) T. haneyi can superinfect in the presence of T. equi infection and co-persists for minimally 25 months, (2) intravenous challenge with T. haneyi is subclinical, and (3) limited cross-reactive antibody between T. haneyi and T. equi includes reactivity to EMA-1 and EMA-2.
Copyright © 2019 Elsevier B.V. All rights reserved.
Publication Date: 2019-06-12 PubMed ID: 31303207DOI: 10.1016/j.vetpar.2019.06.009Google Scholar: Lookup The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
- Diagnosis
- Disease control
- Disease Diagnosis
- Disease Etiology
- Disease Management
- Disease Outbreaks
- Disease Prevalence
- Disease Surveillance
- Disease Transmission
- Disease Treatment
- Equine Diseases
- Equine Health
- Horses
- Infection
- Infectious Disease
- Theileria equi
- Tick-Borne Diseases
- Veterinary Care
- Veterinary Medicine
- Veterinary Research
- Veterinary Science
Summary
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The research investigates the infection dynamics of two species, Theileria equi and Theileria haneyi, which are tick-borne parasites of horses. Theileria equi has reemerged in the United States mainly due to intravenous transmission and tick causes. A new species, Theileria haneyi, was found near US-Mexico border which could not be detected by usual methods. The researchers compared the two species in terms of clinical disease, infection rate, ability to superinfect, and antibody responses.
Investigation and Comparison of Two Theileria Species
The research was carried out to understand the infection dynamics of newly found Theileria species: Theileria equi and Theileria haneyi. These two species of tick-borne parasites were found in horses with a particular focus on:
- Their capability of superinfection in the presence of each other;
- Comparison of clinical diseases following infection by either species;
- Determining the time required to detect each type of infection; and
- Evaluation of the comparative analysis of antibody responses caused by each organism.
Findings and Results
The findings from the study was enlightening:
- The capacity to cause superinfection, where Theileria haneyi could superinfect a horse already infected with Theileria equi, and vice versa, and co-persist for at least 25 months.
- Intravenous inoculation or infection with Theileria haneyi was found to be subclinical, indicating that the symptoms are not severe enough to diagnose the disease upon physical examination, however, Theileria equi infection notably caused neutropenia – a condition characterized by a lower-than-normal count of neutrophils, a type of white blood cell.
- It took longer to detect anti- Theileria haneyi antibodies (26.67 days post-inoculation) compared to anti-Theileria equi antibodies (11.67 days post-inoculation).
- A splenectomized horse infected with Theileria haneyi and a horse with an intact spleen infected with Theileria equi showed different antibody responses. There was observed limited cross-reactive antibodies between these two species, which includes reactivity to EMA-1 and EMA-2. This means that the body’s immune system responded to these infections differently, which can impact the diagnosis and treatment of these diseases.
Implications of the Research
The research is significant as it helps broaden our understanding of Theileria infections, specifically their clinical symptoms, diagnosis, and the body’s immune response. It adds to the body of scientific knowledge, informing future research and impacting potential testing and treatment strategies. Most importantly it recognizes the threat of these exotic infections becoming more widespread due to the global movement and climate change.
Cite This Article
APA
Sears KP, Kappmeyer LS, Wise LN, Silva M, Ueti MW, White S, Reif KE, Knowles DP.
(2019).
Infection dynamics of Theileria equi and Theileria haneyi, a newly discovered apicomplexan of the horse.
Vet Parasitol, 271, 68-75.
https://doi.org/10.1016/j.vetpar.2019.06.009 Publication
Researcher Affiliations
- Veterinary Clinical Sciences, Washington State University, Pullman, WA, USA. Electronic address: kellyp.sears@wsu.edu.
- Animal Disease Research Unit, Agricultural Research Service, United States Department of Agriculture, Pullman, WA, USA.
- Animal Disease Research Unit, Agricultural Research Service, United States Department of Agriculture, Pullman, WA, USA; St. George's University, School of Veterinary Medicine True Blue Campus, St. George's, Grenada West Indies, Grenada.
- Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA, USA.
- Animal Disease Research Unit, Agricultural Research Service, United States Department of Agriculture, Pullman, WA, USA.
- Animal Disease Research Unit, Agricultural Research Service, United States Department of Agriculture, Pullman, WA, USA; Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA, USA.
- Animal Disease Research Unit, Agricultural Research Service, United States Department of Agriculture, Pullman, WA, USA; Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA, USA.
- Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA, USA.
MeSH Terms
- Animals
- Antibodies, Protozoan / blood
- Horse Diseases / immunology
- Horse Diseases / pathology
- Horses
- Texas
- Theileria
- Theileriasis / immunology
- Theileriasis / pathology
Citations
This article has been cited 17 times.- Onzere CK, Hulbert M, Sears KP, Williams LBA, Fry LM. Tulathromycin and Diclazuril Lack Efficacy against Theileria haneyi, but Tulathromycin Is Not Associated with Adverse Clinical Effects in Six Treated Adult Horses. Pathogens 2023 Mar 14;12(3).
- Grimsley M, Hicks J, Zeineldin M, Murphy G, Sigafoose T. Complete Genome Sequence of Theileria equi NVSL354. Microbiol Resour Announc 2023 Feb 16;12(2):e0080922.
- Sears KP, Knowles DP, Fry LM. Clinical Progression of Theileria haneyi in Splenectomized Horses Reveals Decreased Virulence Compared to Theileria equi. Pathogens 2022 Feb 16;11(2).
- Almazán C, Scimeca RC, Reichard MV, Mosqueda J. Babesiosis and Theileriosis in North America. Pathogens 2022 Jan 27;11(2).
- Rocafort-Ferrer G, Leblond A, Joulié A, René-Martellet M, Sandoz A, Poux V, Pradier S, Barry S, Vial L, Legrand L. Molecular assessment of Theileria equi and Babesia caballi prevalence in horses and ticks on horses in southeastern France. Parasitol Res 2022 Mar;121(3):999-1008.
- Schnittger L, Ganzinelli S, Bhoora R, Omondi D, Nijhof AM, Florin-Christensen M. The Piroplasmida Babesia, Cytauxzoon, and Theileria in farm and companion animals: species compilation, molecular phylogeny, and evolutionary insights. Parasitol Res 2022 May;121(5):1207-1245.
- Elsawy BSM, Nassar AM, Alzan HF, Bhoora RV, Ozubek S, Mahmoud MS, Kandil OM, Mahdy OA. Rapid Detection of Equine Piroplasms Using Multiplex PCR and First Genetic Characterization of Theileria haneyi in Egypt. Pathogens 2021 Oct 31;10(11).
- Galon EM, Macalanda AM, Garcia MM, Ibasco CJ, Garvida A, Ji S, Zafar I, Hasegawa Y, Liu M, Ybañez RH, Umemiya-Shirafuji R, Ybañez A, Claveria F, Xuan X. Molecular Identification of Selected Tick-Borne Protozoan and Bacterial Pathogens in Thoroughbred Racehorses in Cavite, Philippines. Pathogens 2021 Oct 13;10(10).
- Bastos RG, Sears KP, Dinkel KD, Kappmeyer L, Ueti MW, Knowles DP, Fry LM. Development of an Indirect ELISA to Detect Equine Antibodies to Theileria haneyi. Pathogens 2021 Feb 27;10(3).
- Sears K, Knowles D, Dinkel K, Mshelia PW, Onzere C, Silva M, Fry L. Imidocarb Dipropionate Lacks Efficacy against Theileria haneyi and Fails to Consistently Clear Theileria equi in Horses Co-Infected with T. haneyi. Pathogens 2020 Dec 10;9(12).
- Tirosh-Levy S, Gottlieb Y, Fry LM, Knowles DP, Steinman A. Twenty Years of Equine Piroplasmosis Research: Global Distribution, Molecular Diagnosis, and Phylogeny. Pathogens 2020 Nov 8;9(11).
- Mshelia PW, Kappmeyer L, Johnson WC, Kudi CA, Oluyinka OO, Balogun EO, Richard EE, Onoja E, Sears KP, Ueti MW. Molecular detection of Theileria species and Babesia caballi from horses in Nigeria. Parasitol Res 2020 Sep;119(9):2955-2963.
- Bishop RP, Kappmeyer LS, Onzere CK, Odongo DO, Githaka N, Sears KP, Knowles DP, Fry LM. Equid infective Theileria cluster in distinct 18S rRNA gene clades comprising multiple taxa with unusually broad mammalian host ranges. Parasit Vectors 2020 May 19;13(1):261.
- Qin S, Kulabieke T, Mizhamuhan D, Zhang M, Jin M, Abula G, Pi M, Wang H, Zhang Y, Guo Q. Molecular Prevalence and Genotypic Diversity of Theileria equi in Xinjiang, China, Based on Three Genes. Vet Sci 2025 Dec 25;13(1).
- Poh KC, Oyen K, Onzere CK, Kappmeyer LS, Bastos RG. Haemaphysalis longicornis ticks are unable to transstadially transmit Theileria haneyi to horses. Front Vet Sci 2025;12:1572944.
- de Albuquerque CV, da Silva Andrade M, de Freitas MS, Paulino PG, Santos HA, de Tarso Landgraf Botteon P. Significance of Anaplasma phagocytophilum, Babesia caballi, and Theileria equi as etiologic agents in horses with clinical manifestations from the metropolitan area of Rio De Janeiro, Brazil. Trop Anim Health Prod 2024 Sep 21;56(8):268.
- Jongejan F, Du C, Papadopoulos E, Blanda V, Di Bella S, Cannella V, Guercio A, Vicari D, Tirosh-Levy S, Steinman A, Baneth G, van Keulen S, Hulsebos I, Berger L, Wang X. Diagnostic performance of a rapid immunochromatographic test for the simultaneous detection of antibodies to Theileria equi and Babesia caballi in horses and donkeys. Parasit Vectors 2024 Mar 28;17(1):160.
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