Aspectos clínicos e patológicos de dois surtos de doença neurológica em equinos causadas por vírus do complexo encefalomielite equina leste no estado de Mato Grosso

Abstract

Outbreaks of equine encephalomyelitis caused by the eastern equine encephalomyelitis complex were observed in July and September 2022 on two properties in the state of Mato Grosso, located in the municipalities of Santo Antônio do Leverger (Property A) and Sorriso (Property B). On Property A there were four crossbred mares. Two presented neurological signs characterized by incoordination with difficulty in walking, slight loss of proprioception, intense apathy and died, with morbidity of 50% (2/4) and lethality of 100% (2/2). Both were submitted to necropsy (Equines 1 and 2). On Property B there were 26 horses, of which one mare suffered from motor incoordination, recumbency and pedaling and received treatment, however the disease progressed to death and was subsequently necropsied (horse 3). In this case, the mortality and lethality rate was 0.03% (1/26) and 100%, respectively. In all three, the main macroscopic observation was mild hyperemia of the meninges. On microscopy, there was diffuse, non-suppurative encephalomyelitis, with meningeal lymphoplasmacytic infiltration noted and in the Virchow Robin space, around vessels (perivascular cuff). In brain samples collected during necropsy and submitted to RT-qPCR, amplification occurred for Alphavirus and Madariaga Virus in horses 1 and 2 and for Alphavirus and Eastern equine encephalitis complex in horse 3. The epidemiological and clinicopathological aspects of equine encephalomyelitis in horses are discussed.