Some serological reactions to “brucella” antigen in the horse.

This research article investigates the immune response in horses to the antigens of the bacteria Brucella, which is associated with the disease brucellosis. Using 73 serum samples from 69 horses and one zebra, various diagnostic tests were performed which suggest that horses can potentially show a farely significant immune response to Brucella exposure.

Research Context

• The study examined the immune reaction of horses and a zebra to the Brucella antigen, which is associated with the brucellosis disease. Brucellosis is an infectious disease caused by bacteria of the genus Brucella.
• The investigators sourced 73 samples of serum from 69 horses and one zebra. Fifty-one of the samples were submitted by practicing veterinary doctors. Out of these, 22 samples were linked with clinical conditions that could have potentially been due to brucellosis. The remaining samples were from healthy horses, with some exposed to infected cattle, and others known not to have been exposed to brucellosis at all.

Research Methodology

• The study used multiple diagnostic tests on the collected samples, which included the Rose Bengal Plate, serum tube agglutination, complement fixation, and anti-equine globulin (Coombs’) tests.
• These diagnostic tests are commonly adopted for screening for infections and diseases, including brucellosis. The Rose Bengal plate test is a straightforward and rapid test that detects antibodies against Brucella. The agglutination tests involve the clumping of cells or particles in response to interaction with specific antibodies. The complement fixation test is used to detect the presence of specific antibodies in serum, while the Coombs’ test is used to determine the existence of antibodies that can cause destruction of blood cells.

Main Findings

• The study uncovered that more reactions at accepted diagnostic levels were achieved using the anti-globulin and complement fixation tests than with the agglutination test. Retrospectively, this suggests that the former tests may be more efficient in detecting brucellosis in horses than the latter.
• Two horses, however, displayed inconclusive results to the antiglobulin test, which could have been due to exposure to Brucella.
• The study also underlines the possibility of disparities between diagnostic tests, with certain cases showing positive reactions to one test, yet negative reactions to another. For example, eight out of nine positive results from the Rose Bengal test were confirmed by a reaction at diagnostic level in at least one of the other tests, but two samples showing a reaction at diagnostic level to the other tests gave a negative Rose Bengal result.