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Veterinary research communications2025; 50(1); 52; doi: 10.1007/s11259-025-10993-5

Equine infectious anemia in Brazilian equestrian tourism horses: serological, molecular, and biochemical assessment showing high EIAV seroprevalence and elevated gamma-glutamyl transferase (GGT) levels.

Abstract: Equine infectious anemia (EIA) is a chronic disease caused by the equine infectious anemia virus (EIAV), a member of the Retroviridae family and the Lentivirus genus. Most infected animals are asymptomatic carriers, which makes clinical diagnosis challenging. This study aimed to conduct a clinical and laboratory evaluation of EIA in equids used for equestrian tourism in Jericoacoara National Park, Ceará, Brazil. A total of 112 equids (104 horses and 8 mules) underwent clinical, hematological, biochemical, serological, and molecular assessments. The EIAV seropositivity rates were 11.6% by AGID, 36.6% by gp90 ELISA, and 25.9% by p26 ELISA. Amplified DNA in the tat-gag PCR assay was detected in 23.2% of the samples. Phylogenetic analyses confirmed the genetic diversity of EIAV circulating in Brazil. This diversity may influence immune responses and consequently diagnostic outcomes. A significant correlation was observed between animals seropositive in diagnostic tests for EIAV and the elevated levels of the gamma-glutamyl transferase (GGT) enzyme, suggesting possible subclinical hepatic involvement. The findings reinforce the value of a comprehensive diagnostic strategy and the monitoring of biochemical parameters in seropositive animals, while also highlighting deficiencies in current EIA control measures.
© 2025. The Author(s), under exclusive licence to Springer Nature B.V.
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Publication Date: 2025-11-27 PubMed ID: 41307751PubMed Central: 12269943DOI: 10.1007/s11259-025-10993-5Google Scholar: Lookup
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Summary

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Equine infectious anemia virus (EIAV) infection was studied in horses and mules used for tourism in a Brazilian national park, revealing high rates of infection and associated liver enzyme changes, highlighting challenges in diagnosis and disease control.

Introduction and Study Objective

  • Equine infectious anemia (EIA) is a chronic viral disease caused by EIAV, a retrovirus belonging to the Lentivirus genus.
  • Most infected horses show no clinical symptoms, making it difficult to detect infection based on physical signs alone.
  • The study focused on equids used in equestrian tourism at Jericoacoara National Park, Ceará, Brazil.
  • Purpose was to perform a detailed clinical and laboratory evaluation to assess EIA prevalence and associated biological effects in this population.

Study Population and Methods

  • Sample consisted of 112 equids: 104 horses and 8 mules.
  • Various assessments were performed on each animal:
    • Clinical evaluation: looking for physical signs of disease.
    • Hematological tests: blood cell counts and related parameters.
    • Biochemical tests: including liver enzyme measurements.
    • Serological tests: detecting antibodies against EIAV using AGID (agar gel immunodiffusion) and two ELISA assays targeting gp90 and p26 viral proteins.
    • Molecular biology tests: PCR targeting the tat-gag region to detect viral DNA.

Key Findings: Seroprevalence and Molecular Detection

  • Seropositivity rates varied depending on the test:
    • 11.6% positive by AGID test (the traditional confirmatory test).
    • 36.6% positive by gp90 ELISA, indicating a higher sensitivity.
    • 25.9% positive by p26 ELISA.
  • PCR detected viral DNA in 23.2% of samples, confirming active infection at the molecular level.
  • Phylogenetic analysis of PCR-positive samples showed significant genetic diversity among EIAV strains circulating in Brazil.

Implications of Genetic Diversity

  • The presence of genetically diverse EIAV strains may impact the host immune response.
  • Variability can affect accuracy of diagnostic tests, as diverse strains might differ in viral proteins targeted by serological assays.
  • This genetic heterogeneity could lead to false negatives or variation in antibody detection sensitivity across tests.

Biochemical Findings and Liver Enzyme Correlation

  • Gamma-glutamyl transferase (GGT) levels were found to be elevated in seropositive animals.
  • GGT is a liver enzyme, and its elevation suggests possible subclinical involvement of liver function during EIAV infection.
  • This finding indicates that even asymptomatic carriers may experience subtle hepatic effects.
  • Monitoring biochemical parameters like GGT can thus provide added insight into the disease state and its effects beyond serological diagnosis.

Conclusions and Significance

  • The study highlights a relatively high prevalence of EIAV infection in equids used for tourism in this region of Brazil.
  • Combination of serological, molecular, and biochemical testing improves the detection and understanding of the disease.
  • Current EIA control strategies may be insufficient, given the high seroprevalence and viral diversity.
  • Regular biochemical and serological monitoring is recommended to manage infected populations and to identify subclinical cases.
  • The results underscore the need for enhanced diagnostic tools and control measures tailored to diverse viral strains and regional epidemiology.

Cite This Article

APA
Costa VMD, de Aguiar Filho RN, Braz GF, Paz CFR, Drumond BP, Teixeira BM, Kroon EG. (2025). Equine infectious anemia in Brazilian equestrian tourism horses: serological, molecular, and biochemical assessment showing high EIAV seroprevalence and elevated gamma-glutamyl transferase (GGT) levels. Vet Res Commun, 50(1), 52. https://doi.org/10.1007/s11259-025-10993-5

Publication

Veterinary research communications
ISSN: 1573-7446
NlmUniqueID: 8100520
Country: Switzerland
Language: English
Volume: 50
Issue: 1
Pages: 52

Researcher Affiliations

Costa, Viviane Maria Dias
  • Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais (ICB/UFMG), Belo Horizonte, Minas Gerais, Brazil.
de Aguiar Filho, Raimundo Nonato
  • Centro Universitário, INTA, UNINTA, Sobral, Ceará, Brazil.
Braz, Gissandra Farias
  • Centro Universitário, INTA, UNINTA, Sobral, Ceará, Brazil.
Paz, Cahuê Francisco Rosa
  • Centro Universitário, INTA, UNINTA, Sobral, Ceará, Brazil.
Drumond, Betania Paiva
  • Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais (ICB/UFMG), Belo Horizonte, Minas Gerais, Brazil.
Teixeira, Bruno Marques
  • Centro Universitário, INTA, UNINTA, Sobral, Ceará, Brazil.
Kroon, Erna Geessien
  • Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais (ICB/UFMG), Belo Horizonte, Minas Gerais, Brazil. ernagkroon@gmail.com.

MeSH Terms

  • Animals
  • Horses
  • Brazil / epidemiology
  • Equine Infectious Anemia / epidemiology
  • Equine Infectious Anemia / virology
  • Equine Infectious Anemia / blood
  • Seroepidemiologic Studies
  • Infectious Anemia Virus, Equine / genetics
  • Infectious Anemia Virus, Equine / isolation & purification
  • gamma-Glutamyltransferase / blood
  • Female
  • Male
  • Phylogeny
  • Enzyme-Linked Immunosorbent Assay / veterinary

Grant Funding

  • 001 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
  • 315750/2020-0 / Conselho Nacional de Desenvolvimento Científico e Tecnológico
  • PPM-00452-17 / Fundação de Amparo à Pesquisa do Estado de Minas Gerais

Conflict of Interest Statement

Declarations. Institutional review board statement: This study was approved by the ethics committee on the use of animals (CEUA – UNINTA) under protocol No. 2019.07.008-P. Competing interests: The authors declare no competing interests.

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