Designation of cut-off point rate for ELISA test in Diagnosis of Human Brucellosis

Abstract

Brucellosis a world-wide disease having diverse clinical manifestations, affecting hundreds of individuals annually. Its prevalence is different in different countries and even in different regions of the same country. It can be diagnosed by different methods each one having different sensitivity and specificity and even it depends on the laboratory facilities of the concern area. Although it is usually screened by Slide Agglutination Test (SAT) and blood culture techniques, but these may produce false positive results and having extended time for test results respectively. A total of 82 patients were selected over a one-year period between March 2014 and April 2015. All patients' sera were processed for culture using BACTEC 9240 system followed by testing by ELISA. Among 82 suspected patients, only 30 (%) were positive for culture and remaining 52 (%) were negative.While ELISA IgM and IgG were 15% and 22% respectively among culture positive samples. ROC curve showed the behavior of the sensitivity and specificity of ELISA IgG and IgM by using different cut-off points. In patients with brucellosis, the mean of serum IgG was greater than IgM, significantly (P<0.001). ELISA IgG test was more reliable than ELISA IgM test in diagnosis of brucellosis in Iran.