Use of eluates of filter paper blood spots in ELISA for the serodiagnosis of leprosy.

Blood samples were collected from 59 leprosy patients and 35 normal healthy subjects by veni-puncture and finger prick methods to obtain serum samples and blood spots on filter paper respectively. The serum samples at 1:300 dilutions and the eluates of dried blood spots at 1:40, 1:80, 1:160 and 1:320 dilutions were applied in ELISA to measure the antibody levels (IgM) against synthetic ND-O-BSA antigen. The antibody levels were found to be high in the multibacillary leprosy patients than the pauci-bacillary patients irrespective of whether serum samples or eluates were used. The OD values obtained at 1:160 dilution of the eluates were equivalent to that of values obtained at 1:300 dilution of the serum samples. The positivities differ in different dilution of the eluates, showing the highest in the 1:40 dilution and the lowest in the 1:320 dilution.