The present work evaluated the occurrence of seropositive equids for eastern encephalomyelitis virus (EEE), western encephalomyelitis virus (WEE), Venezuelan encephalomyelitis virus (VEE) and infectious anemia virus (IAV) in the Pantanal, Savannah and Amazon biomes of Mato Grosso State, Brazil. The detection of antibodies against IAV was carried out in 886 sera of equids by the immunodiffusion test, and antibodies against EEE, WEE and VEE were evaluated in 473 sera by the seroneutralization test performed in VERO cells. The results showed 46 IAV seropositive equids (5.1%). No sera was positive in the Amazon region, and the Pantanal biome showed a higher occurrence with 36.6% of seropositives (P < 0.05). No sera was positive for WEE virus and 168 (35.5%) and 31 (6.5%) equids were positive for EEE and VEE respectively. Higher frequencies (P < 0.05) were observed for EEE in the Pantanal and Amazon regions with 45.8% and 62.0% respectively. Regarding EEV, no differences were observed between the Pantanal, Savannah and Amazon regions, presenting 4.1%, 6.4% and 10.3% respectively (P > 0.05). Despite that IAV was not observed in equids from the Amazon, the occurrence of seropositive equids agree with the Brazilian prevalence. The differences of EEE and VEE behavior between biomes reinforce the presence of animal reservoirs, along with environmental and weather characteristics that support vector maintenance, which favor the presence of the viral infection in Mato Grosso State.
Equine encephalomyelitis virus; equine infectious anemia virus; serology; epidemiology; equids; Mato Grosso