Predictive Value of Gelatin Particle Agglutination Test (GPAT) in Leprosy Detection

Detection of Mycobacterium leprae infection prior to the onset of the clinical disease may be very important for epidemiological study of leprosy and its eradication. By adding diagnosis through early recognition, early treatment can be commenced, thus it would greatly help in the limitation of transmission of M. leprae and in reduction of the degree of deformities. The aims of our study was to evaluate the value of GPAT using semisynthetic trisaccharides antigen (NT-P-BSA, manufactured by FUJIREBIO-INC-Japan and provided by WHO) in early detection of leprosy. 1,030 apparently normal persons including 680 household contacts of patients of leprosy with average 3 years of contact and 350 people living in areas free of leprosy were tested with GPAT. Among 135 household contacts showing positive GPAT, 17 developed leprosy (12.8%) within 14-57 months of becoming positive while among 884 people with GPAT negative, none (0%) developed the disease during the same period of follow-up. In children, a high titer of antibodies constitutes a valuable indicator of high risk in developing the disease: 63.1% of them developed clinical leprosy while it was only 7.7% in adults. 100% leprosy children showing GPAT positive at serum dilution of 1:64 or over have developed leprosy. In conclusion, GPAT has shown that children with GPAT positive at high titer of 1:64 or over and whose mother/father being a leprosy patient can be considered as the highest risk group of eventually developing the disease. All household contacts with GPAT high positivity have been actively followed-up until now. In this sense, GPAT has proved to be an indicator for detection of sub-clinical leprosy infection with high chances of developing clinical disease.