Value of different serological tests in the diagnosis of bovine brucellosis in the Amazonian region.

The high prevalence of brucellosis is one of the most serious animal health problems affecting cattle and buffalo herds of the Amazonian region. Modern diagnostic methods are not used or not even known, and thus test results are not available in that region. Therefore, in this study a total of 878 selected sera were subjected to comparative examination by five different serological tests (buffered plate agglutination test, tube agglutination test, complement fixation test, indirect ELISA, competitive ELISA). Indirect ELISA gave the highest number of positive results, except in samples derived from the Marajó island, for which the competitive ELISA proved to be the most sensitive. The sensitivity of the classical tests (agglutination, complement fixation) was markedly lower than that of the two ELISAs. After vaccination of 2-month-old heifer calves with the B19 vaccine, all tests showed a 50-60% seropositivity, which disappeared within four months.