Introduction Arboviruses are an important public health problem in Brazil, in especially flaviviruses, including the Saint Louis encephalitis virus (SLEV) and the Rocio virus (ROCV), are especially problematic. These viruses are transmitted to humans or other vertebrates through arthropod bites and may cause diseases with clinical manifestations that range from asymptomatic infection, viral hemorrhagic fever to encephalitis. Methods A serological survey of horses from various regions of Brazil using an enzyme-linked immunosorbent assay (ELISA) with recombinant SLEV domain III peptides and ROCV E protein as antigens. Results Overall, 415 (55.1%) of the 753 horses that were screened were seropositive for flavivirus and, among them, monotypic reactions were observed to SLEV in 93 (12.3%) and to ROCV in 46 (6.1%). These results suggested that these viruses, or other closely related viruses, are infecting horses in Brazil. However, none of the studied horses presented central nervous system infection symptoms. Conclusions Our results suggest that SLEV and ROCV previously circulated among horses in northeast, west-central and southeast Brazil.

Since the emergence of West Nile virus (WNV) in North America in 1999, there have been several reports of WNV activity in Central and South American countries. To detect WNV in Brazil, we performed a serological survey of horses from different regions of Brazil using recombinant peptides from domain III of WNV. Positive samples were validated with the neutralisation test. Our results showed that of 79 ELISA-positive horses, nine expressed WNV-specific neutralising antibodies. Eight of the infected horses were from the state of Mato Grosso do Sul and one was from the state of Paraíba. Our results provide additional evidence for the emergence of WNV in Brazil and for its circulation in multiple regions of the country.

Objetivou-se avaliar a atividade sérica das enzimas creatina quinase (CK) e aspartato aminotransferase (AST), enzimas de extravazamento responsivas à lesão muscular, de equinos de salto submetidos à biópsia muscular e a um teste de exercício padronizado, envolvendo saltos incrementais. Foram utilizados três grupos de animais, um com histórico de desempenho superior (SP), um com histórico inferior (IP) e um grupo controle (CG). Todos os grupos foram submetidos à biópsia muscular no gluteus medius e somente os grupos SP e IP ao teste de saltos incrementais (IJT), 24h após a biópsia. O IJT foi constituído de três estágios de alturas progressivas, com 40 saltos cada, nas alturas de 40, 60 e 80cm. Amostras de sangue foram coletadas antes da biópsia, 6h e 24h após o exercício. Os níveis de atividade sérica da CK elevaram-se 6h e diminuíram 24h após o exercício em todos os grupos, inclusive no CG. A atividade da AST não demonstrou aumento após a realização da biópsia e do exercício. Não foi visto aumento da atividade de ambas enzimas mensuradas que pudesse ser atribuído ao exercício, possivelmente pela baixa duração e/ou intensidade do mesmo. Conclui-se que a biópsia muscular caracterizou estímulo suficiente para haver extravasamento somente da enzima muscular CK para o plasma, e consequente detecção de aumento de sua atividade sérica, enquanto o teste de exercício padronizado realizado não.

The objective was to evaluate serum activity of the enzymes creatine kinase (CK) and aspartate aminotransferase (AST), which are leakage enzymes responsive to muscle injury, of athletic horses that underwent muscle biopsy and incremental jump test (IJT) involving incremental jumps. The animals were grouped as follows: the first group, horses with history of superior performance (SP); the second, with a history of inferior performance (IP); and lastly, a control group (CG). All groups underwent biopsy of the gluteus medius muscle, while groups SP and IP were also submitted to the incremental jump test (IJT) 24 hours after biopsy. The IJT consisted of three stages with 40 jumps each, where jump height increased progressively, from 40 to 60 and last, 80cm. Blood samples were drawn before biopsy, and 6 and 24 hours after the exercise as well. The levels of CK serum activity increased 6 hours after exercise and decreased 24 hours later in all groups, including CG. AST activity did not increase after biopsy and exercise. There was no increase of both enzyme activities that could be attributed to the exercise, possibly due to exercise short duration and/or low intensity. We conclude that the muscle biopsy was able to show that there was enough stimulus to cause CK enzyme leakage into the plasma, and consequent detection of increased serum activity, while the incremental jump test did not.