Anticorpos antialfavírus detectados em equinos durante diferentes epizootias de encefalite equina, Paraíba, 2009

Abstract

Neuroinvasive diseases diagnosis in horses is a major issue in defining surveillance policies in Brazil. In order to determine the prevalence of hemagglutination inhibition antibodies to alphaviruses and compare the results obtained from this technique for EEE virus to those obtained from plaque reduction neutralization test, blood sample was taken from 182 horses during the investigation of epizootics occurred in 15 municipalities of Paraiba state, in 2009, where there were reports of death or illness in horses. The clinical prevalence for EEE virus, assessed from sick animals, was 12.8%, while the real (PRNT) and the apparent (IH) prevalences were 63.7% and 54.3%, respectively. Compared to the PRNT, the IH test has shown a sensibility of 77.6% and a specificity of 86.4%. The positive and negative predictive values were 90.9% and 68.7%. A high number of serologically reactive animals without apparent symptoms were revealed. These results, associated to clinical and epidemiological data and to virological diagnosis (PCR), were able to confirm the epizootics in the area for EEE, and demonstrate that the IH test can be used for screening in serological surveys because of its high sensibility and specificity.