MAINTENANCE OF BRUCELLA-ABORTUS FREE HERDS - A REVIEW WITH EMPHASIS ON THE EPIDEMIOLOGY AND THE PROBLEMS IN DIAGNOSING BRUCELLOSIS IN AREASOF LOW-PREVALENCE
Z. Bercovich, MAINTENANCE OF BRUCELLA-ABORTUS FREE HERDS - A REVIEW WITH EMPHASIS ON THE EPIDEMIOLOGY AND THE PROBLEMS IN DIAGNOSING BRUCELLOSIS IN AREASOF LOW-PREVALENCE, Veterinary quarterly, 20(3), 1998, pp. 81-88
This review covers some epidemiological aspects that allow Brucella to
survive, spread, and maintain itself in the environment. Because the
success of maintaining Brucella-free herds is determined by the effici
ency of the serological tests to detect a single infected animal the l
imitations of the traditional serological tests are emphasized. Serolo
gical tests cannot differentiate between cattle infected with Brucella
and cattle infected with microorganisms that serologically cross-reac
t with B. abortus antigen. These cattle and cattle with 'natural' anti
bodies jeopardize the Brucella-free status of a herd. Likewise, infect
ed cattle with serologically inconclusive test results or which elude
detection are also a hazard to Brucella-free herds. Since cattle that
elude detection with serological tests and the presence of non-specifi
c serum antibodies in healthy cattle have long been recignized as prob
lems, it is opportune to reconsider the procedures currently used to d
iagnose brucellosis in individual animals. Use of the skin delayed-typ
e hypersensitivity test in addition to serological tests will signific
antly improve the diagnosis of brucellosis. This will limit the financ
ial loss incurred by outbreaks of brucellosis.