Encefalomielite equina Leste na Ilha de Marajó, Pará

Abstract

Nine cases of equine encephalomyelitis were studied in the Marajó Island, State of Pará, Brazil. The animals had difficulty in maintaining a station, walk in a circle, marked depression, eyelids closed, tongue paralysis, muscle tremors, bruxism, anorexia and dehydration. Some had their ear and eyelid reflexes diminished, decreased tongue tone and tachycardia. Position of self-hearing was observed frequently. The animals were often found leaning on tree trunks and fences to keep themselves on station. At necropsy, they showed hemorrhage of the meninges and spinal cord, and some animals also showed adhesion of the meninges. Histologically there was diffuse encephalitis affecting mainly the gray matter, with meningitis and choroiditis. It was observed the presence of perivascular cuffs consisting of mononuclear inflammatory cells. In two animals it was possible to identificate the Eastern equine encephalitis virus by semi-nested reverse transcription polymerase chain reaction (semi-nested RT-PCR).