الفهرس 
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Abstract
The clinical diagnosis of brucellosis is complicated due to variable incubation periods and absence of apparent clinical signs except abortion. Culture and isolation of Brucella species is regarded as the “gold standard” test for laboratory diagnosis of brucellosis ,its sensitivity is very low because the Brucella is fastidious micro-organism that can easily be over grown by other contaminating bacteria ,more importantly the procedure is associated with high risk of infections to Bacteriology Department personnel. Therefore serological tests are often relied upon for the diagnosis of brucellosis. The first component of implementation of an initial screening assay designed for high throughput is to localize the range and frequency of the disease. In case of livestock, the initial screening needs to be inexpensive, easy to perform, rapid, highly sensitive and specific. Several serological tests such as agglutination test, Rose Bengal test (RBT), card test and other tests have been designed to meet those requirements. Since sensitivity is crucial in the initial screening, the occurrence of some false positive samples must be tolerated in order to detect all resident infections. To identify the false positive reactions, a second test is typically performed. Since the throughput of positive samples is only a fraction of initial samples screened, the second test is usually more expensive and more complicated but designed to maximize the specificity. We suggest solving this problem of diagnosis by using laser induced fluorescence (LIF). LIF can differentiate between labeled O-polysaccharide (OPS) conjugate with antibody presented in positive serum samples and negative samples in absence of antibody. The sensitivity (Se) and specificity (Sp) of tube agglutinations, Rose Bengal and Rivanol test (Riv test), in addition to the laser induced fluorescence (LIF) were performed on 79 sera collected from 79 unknown cows reared in small dairy farms in Egypt. The results showed that agglutinations tested revealed 18 positive out of 79 samples, RBT test revealed 20 positive, Rivanol test revealed 13 positive while LIF test revealed 15 positive. Due to the absence of “gold standard” were calculated the specificity and sensitivity of each test statistically in relation to the other 3 tests. By calculating the sensitivity of the Tube Agglutination Test (TAT ) in relation to Rose Bengal the percentage was (80%), Rivanol( 60%) and LIF (70%), the specificity of TAT was (96.6%) ,Rivanol was (98.3% ) and LIF was (98.3%). In calculating the sensitivity and specificity in relation to Rivanol., results revealed that TAT sensitivity was (100%), RBT was (92.3%) and LIF was ( 92.3%), while specificity was TAT (92.4%) , RBT (87.4%) and LIF( 95.4%) . Calculating the sensitivity and specificity in relation to TAT result revealed that sensitivity of RBT was (88.8%), Rivanol (72.2%) and LIF (72.2%). Specificity of RBT was (93.4%), Rivanol was (100%) and LIF was (96.7%). Comparing the sensitivity and specificity of LIF to the other 3 tests, it was proven that it is more valid. Therefore, based on those data it can be concluded that regimes using RBT and Rivanol test could be suitable for diagnosis of brucellosis in dairy farms in Egypt, and LIF can be used as secondary test for detections of false positive reactors. Due to costs and ease of performance, the LIF may be adapted as confirmatory test, but its performance may be optimized by altering cut-off points to suit the Egyptian conditions.