Newly designed PCR assays based on the ema-10 and ema-11 genes confirm the circulation of Theileria haneyi in horses in Brazil.
Abstract: Equine Piroplasmosis (EP) is a tick-borne disease caused by the protozoan parasites Babesia caballi, Theileria equi, and Theileria haneyi, characterized by intravascular hemolysis and associated systemic illness. Although T. equi and B. caballi have been widely reported in some regions of Brazil, data from other states are limited. Additionally, despite reports of T. equi genotype C, currently recognized as T. haneyi, has been identified in Brazil, there are no investigations using T. haneyi-specific molecular tools. This study assessed the presence of these three agents in horses from Baixada Maranhense microregion (n = 34), northeastern Brazil, and in horses from an equestrian center (n = 12) in Guará, southeastern Brazil. Of 46 horse DNA samples, one (2.1%) from an imported animal in the equestrian center tested positive for T. haneyi in ema-10 and ema-11-based PCR assays. Two animals tested positive for T. equi in a species-specific PCR (ema-1), and all samples were negative for B. caballi. BLASTn analysis showed ema-10 and ema-11 sequences shared 98.9% to 99.3% identity with T. haneyi detected in a horse at the U.S.-Mexico border. Despite the small sample size, this study confirms the presence of T. haneyi in Brazil and the need for monitoring imported animals. A Piroplasmose Equina é uma doença transmitida por carrapatos, causada pelos protozoários , e , caracterizada por hemólise intravascular e quadro clínico sistêmico. Embora e sejam amplamente relatados em algumas regiões do Brasil, há informações limitadas em outros estados. Apesar de relatos do genótipo C de , atualmente reconhecido como , no Brasil, não há estudos com ferramentas moleculares específicas para . Este estudo verificou a presença desses três agentes em cavalos amostrados na microregião da Baixada Maranhense (n = 34), no nordeste, e de um centro equestre (n = 12) em Guará, no sudeste do Brasil. Dentre as 46 amostras analisadas, uma (2,1%) coletada de um animal importado, foi positiva para nos ensaios de PCR ( e ). Dois animais foram positivos para em PCR específico (), e todas as amostras foram negativas para . A análise do BLASTn mostrou identidade de 98,9% a 99,3% com detectado em um cavalo amostrado na fronteira EUA-México. Embora o número de animais amostrados seja pequeno, o estudo confirma a presença de no Brasil e a necessidade de monitoramento dos animais importados.
Publication Date: 2025-10-17 PubMed ID: 41124531PubMed Central: PMC12643233DOI: 10.1590/S1984-29612025049Google Scholar: Lookup
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Summary
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New molecular tests targeting specific genes have confirmed that the parasite Theileria haneyi, which causes tick-borne disease in horses, is present in Brazil.
Background
- Equine Piroplasmosis (EP) is a disease in horses caused by three protozoan parasites: Babesia caballi, Theileria equi, and Theileria haneyi.
- The disease is transmitted by ticks and leads to the destruction of red blood cells (intravascular hemolysis), causing systemic illness in infected horses.
- Apart from T. equi and B. caballi, which are well-studied in some Brazilian regions, T. haneyi has been less investigated in Brazil using molecular diagnostic methods.
- Previously, a genotype of T. equi called genotype C has been identified but is now classified as T. haneyi.
Study Objectives
- To evaluate the presence of B. caballi, T. equi, and T. haneyi in horses from two regions in Brazil: Baixada Maranhense (northeast) and Guará (southeast).
- To apply newly designed PCR assays specifically targeting the ema-10 and ema-11 genes for detecting T. haneyi.
- To confirm if T. haneyi is circulating in Brazilian horses and assess the importance of monitoring imported animals.
Methods
- Collected blood samples from 46 horses (34 in Baixada Maranhense and 12 in Guará equestrian center).
- Used PCR assays targeting:
- ema-1 gene for T. equi detection (species-specific).
- ema-10 and ema-11 genes for T. haneyi detection (newly designed assays).
- Other assays for B. caballi detection.
- Sequenced PCR products and performed BLASTn analysis comparing sequences to known reference strains.
Key Findings
- One horse sample (2.1%) from an imported animal in the equestrian center tested positive for T. haneyi using the ema-10 and ema-11 PCR assays.
- Two other horses tested positive for T. equi through the ema-1 PCR assay.
- All samples were negative for B. caballi.
- The ema-10 and ema-11 sequences from the detected T. haneyi showed a very high identity (98.9% – 99.3%) to a strain detected previously at the U.S.-Mexico border, confirming they belong to the same species.
Study Significance and Conclusions
- This is the first confirmed molecular evidence of Theileria haneyi in horses in Brazil using newly designed, gene-specific PCR assays.
- The detection was in a horse imported to Brazil, indicating a potential route for introduction of the parasite.
- Although the sample size was small, the results emphasize the importance of consistent surveillance and monitoring, especially in imported animals, to prevent disease spread.
- The study fills a knowledge gap due to the lack of prior specific molecular tools applied for T. haneyi detection in Brazil.
Implications for Veterinary Medicine and Disease Control
- Veterinary practitioners should be aware of the presence of T. haneyi alongside other EP agents in Brazil.
- Imported horses represent a risk of introducing new strains of EP-causing parasites; therefore, mandatory screening and monitoring protocols are essential to reduce spread.
- Improved molecular diagnostic tools as applied in this study can lead to more accurate epidemiological studies and better-informed control strategies.
Cite This Article
APA
Machado RZ, André MR, Pereira JG, Oliveira MDSC, Ribeiro LSDS, Toledo CZP, Gonçalves LR.
(2025).
Newly designed PCR assays based on the ema-10 and ema-11 genes confirm the circulation of Theileria haneyi in horses in Brazil.
Rev Bras Parasitol Vet, 34(3), e005225.
https://doi.org/10.1590/S1984-29612025049 Publication
Researcher Affiliations
- Universidade Estadual Paulista - UNESP, Faculdade de Ciências Agrárias e Veterinárias - FCAV, Departamento de Patologia, Reprodução e Saúde Única, Vector-Borne Bioagents Laboratory - VBBL, Jaboticabal, SP, Brasil.
- Universidade Estadual Paulista - UNESP, Faculdade de Ciências Agrárias e Veterinárias - FCAV, Departamento de Patologia, Reprodução e Saúde Única, Vector-Borne Bioagents Laboratory - VBBL, Jaboticabal, SP, Brasil.
- Universidade Estadual do Maranhão - UEMA, Departamento de Patologia, São Luís, MA, Brasil.
- Universidade Estadual do Maranhão - UEMA, Departamento de Patologia, São Luís, MA, Brasil.
- Universidade Estadual do Maranhão - UEMA, Departamento de Patologia, São Luís, MA, Brasil.
- Universidade Estadual Paulista - UNESP, Faculdade de Ciências Agrárias e Veterinárias - FCAV, Jaboticabal, SP, Brasil.
- Imunodot Diagnósticos Veterinários - IMUNODOT, Jaboticabal, SP, Brasil.
MeSH Terms
- Animals
- Horses / parasitology
- Theileria / genetics
- Theileria / isolation & purification
- Brazil
- Horse Diseases / parasitology
- Horse Diseases / diagnosis
- Theileriasis / diagnosis
- Theileriasis / parasitology
- Theileriasis / epidemiology
- Polymerase Chain Reaction / methods
- DNA, Protozoan / analysis
- DNA, Protozoan / genetics
Conflict of Interest Statement
The authors declare no conflicts of interest.
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