Eastern equine encephalitis on Federal District of Brazil and surrounding areas / Encefalomielite equina do leste no Distrito Federal e entorno

ABSTRACT

Background: Eastern equine encephalitis (EEE) is a highly lethal zoonotic disease caused by Eastern equine encephalitisvirus (EEEv), an RNA virus of the genus Alphavirus, family Togaviridae. The transmission of these alphaviruses is throughmosquitoes, mainly species of Culex, Aedes, Anopheles and Culiseta. Horses and humans are considered accidental hostsand the main reservoirs are birds and some wild rodents. The disease has been identified in Brazil by serological studies,but investigations with clinico-pathological descriptions are scarce. The present study aimed to describe the epidemiologyand clinical-pathological findings of four cases of EEE in horses from Midwestern Brazil.Materials, Methods & Results: Four confirmed cases of EEE in horses from the necropsy and histopathology files of theLaboratory of Veterinary Pathology (LPV) of the University of Brasília (UnB) were reviewed. Cases occurred betweenJanuary 2005 and April 2012. Samples of brain and spinal cord samples were fixed in formalin 10%, processed routinelyfor histopathology, and stained by hematoxylin and eosin (HE). Immuno-histochemistry (IHC) with the peroxidase streptoavidin-biotin method was done to confirm the diagnosis of EEEv infection in all cases. The slides were incubated withthe anti-EEEv monoclonal primary antibody (overnight, 1100 dilution). The disease affected both young and adult horses.One case occurred in the summer and the other three in the fall. Clinical signs more frequently observed included circling,blindness, paresis, paralysis, somnolence, ataxia, head pressing, and recumbence...