Evaluation of an ELISA for detection of antibodies to Babesia bigemina in cattle and it's application in an epidemiological survey in Brazil

An indirect enzyme-linked immunosorbent assay (ELISA) using a crude antigen was evaluated for its performance to detect Babesia bigemina antibodies. The sensitivity and specificity were 98.0 per cent and 99.0 per cent, respectively. In agreement with the high specificity, no cross-reactions were verified with sera from calves inoculated three times with 10 7(subscribe) Babesia bovis organisms. With regard to the comparison of ELISA and indirect fluorescent antibody test (IFAT) in detecting antibodies against B. bigemina in calves experimentally infected with five Brazilian geographical isolates of this hemoparasite, IFAT was able to detect antibodies one day earlier in most of the calves' sera. There was a good agreement between results shown by ELISA and IFAT with sera from an enzootically stable area (k=0.61). However, there was no agreement between these serological tests with sera from an enzootically unstable area (k=0.33). The ELISA was employed in an epidemiological survey using with 1,367 sera from four counties in the Pantanal of Mato Grosso do Sul and characterized this region as an enzootically stable area, since the prevalence ranged from 87.7 to 98.9 per cent. Therefore, this ELISA with high sensitivity, specificity and performance similar to IFAT can be employed in serological diagnosis of B. bigemina

Análise de testes de conglutinaçäo rápida para detecçäo de anticorpos contra Babesia bovis e Babesia bigemina / Evaluation of rapid conglutination tests for detection of antibodies against Babesia bovis and Babesia bigemina

Testes de conglutinaçäo rápida foram desenvolvidos para detecçäo de anticorpos contra Babesia bovis e B. bigemina. O primeiro (TCR-B. bovis) apresentou resultados idênticos à imunofluorescência indireta (IFI), na detecçäo de anticorpos resultantes da vacinaçäo com cepas atenuadas de B. bovis, enquanto que o segundo teste de conglutinaçäo (TCR-B. bigemina) divergiu em três dos seis animais na fase inicial da soroconversäo. Aos 28 e 56 dias pós-vacinaçäo (PV) houve coincidência total de resultados. A correlaçäo entre os TCR-B. bovis e IFI no exame dos soros de bovinos de sete estados brasileiros foi de 86,2 por cento, enquanto que a correlaçäo entre TCR-B. bigemina e a prova de imunofluorescência foi de 95,6 por cento. Os resultados demonstraram que os testes de conglutinaçäo podem ser empregados em estudos epidemiológicos com eficiência comparável à imunofluorescência indireta