A rapid latex agglutination test for detection of antibodies in tuberculosis and Hansen's disease

Abstract

Antigens of Mycobacterium w, a saprophytic fast growing organism having antigenic epitopes cross-reactive with Mycobacterium leprae and Mycobacterium tuberculosis, were coated on to latex beads (0.33 μm in size), and the reactivity tested with sera of tuberculosis and Hansen's disease (HD) patients. Seventy nine percent of lepromatous leprosy (LL) and eighty five percent of pulmonary tuberculosis (TB) patients sera showed an agglutination rection easily read by naked eye. Specificity of the test was further checked by testing sera of non-mycobacterial infection cases and all of them were found negative. Among apparently healthy controls, 4.3% were found positive from non-endemic and 8.8% from endemic area. The sensitivity of the assay is further enhanced from 78.7% to 90.4% and 85.7% to 91.6% in both LL HD and pulmonary tuberculosis respectively, by using immune complexes extracted from the patients sera. Potential of these antigen coated beads to detect the two major human mycobacterial diseases, LL HD and pulmonary TB was also put evidence in a double blind study on coded sera samples obtained from various hospitals in India. The antigen coated beads are stable for upto 6 months at 4°C. The latex slide agglutination test reported here, is simple, rapid, easy to perform and can be used even in rural areas of developing countries.