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

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.