EVALUATION OF SEROLOGICAL TESTS FOR DIAGNOSIS OF BRUCELLOSIS IN CAMELS FOR EXPORT AND CONTROL PURPOSES IN THE SUDAN

Abstract

Prevalence of brucellosis in camels in the Sudan is high and the disease
affects their productivity and is a main constraint to their export to the
Arabian Peninsula. This study was designed to compare the Rose Bengal
Plate Test (RBPT), the modified m(RBPT) and competitive ELISA (c
ELISA) for examination of 492 camel serum samples from Kassala State for
brucellosis for export and control purposes. Of the total, 383(77.8%) samples
were examined with the three tests, and 109(22.2%) with the RBPT and
mRBPT and 463 samples were examined with the Serum Agglutination Test
(SAT) , each with both Brucella abortus ( B. abortus) and Yersinia
enterocolitica 0:9 ( Y. enterocolitica 0:9) SAT antigens. After incubation at
37ºC for 24 hours and reading the SATs , the supernatants of each were
tested for agglutination with the heterologus antigen for detection of Y.
enterocolitica O:9 antibodies. The results of RBPT, mRBPT and cELISA
agreed in 28.5% of the positive, 30.3% of the negative and disagreed in 3.9%
of false negative and 36.3% of false positive samples; and 1% of the samples
were negative with the RBPT, positive with the mRBPT and cELISA. Of the
samples examined with the RBPTs, the results agreed in 15.6% of the
negative, 66.1% of the positive and disagreed in 18.4% of the negative with
the RBPT and positive with the mRBPT. Of the 463 samples, 2.6% were
suspected to contain Y. enterocolitica 0:9 antibodies.
It is recommended to screen camels for brucellosis for export and control
purposes with the mRBPT, confirm the positive cases with a confirmatory
test for control and reexamine the negative cases after two months with the
test for to make sure that there are no false negative camels.