Establishment and Evaluation of serological diagnostic tests for Human Cysticercosis

Abstract

Taenia solium (T. solium) infections are of public health concern in most developing countries where diagnosis of the diseases is still a major challenge. This is due to the high cost and technique nature of most of the reliable diagnostic tools that are commercially available. In this study, serological tests developed from crude cyst antigens (Ags) of T. solium, were established at the University of Zambia, and evaluated for their sensitivity and specificity in detecting circulating cysticerci serum antibodies (Abs) in human. The crude antigen was produced from cysts of T. solium collected from pigs from rural Zambia. The antibodies –Enzyme-linked immunosorbent assay (Ab-ELISA) and Electroimmunotransfer blot (EITB) tests were evaluated using a commercial (QualiCode™ Cysticercosis Kit) Immunoblot, in order to estimate their sensitivity and specificity. The Ab-ELISA used a cut off-point of 15 antigen concentration of dilute serum. The Ab-ELISA showed a sensitivity and specificity of 16.67% and 91.94%, respectively. The crude antigen EITB used the 8-10 kDa antigenic bands to detect T. solium sera Abs in human. The commercial blot used any of the six bands 50, 42, 39, 24, 21, 18 and 14 kDa to detect T. solium sera Abs in human. Compared to the commercial blot, whose sensitivity and specificity was 98.00% and 100%, respectively, the crude antigen EITB had a sensitivity of 19.44% and specificity of 85.48%. The crude antigen EITB and Ab-ELISA tests showed significant difference (p<0.05), as the former detected more positives (25) compared to the latter (14) out of 199 samples tested.To our knowledge, this is the first study that attempted to establish an EITB from crude antigens. Most EITB that have been developed so far are based on purified antigens. The study demonstrated that the crude antigen EITB and Ab-ELISA tests are significantly less sensitive than the commercial Immunoblot test. Inspite of this, both the Ab-ELISA and EITB can be useful as screening tests in edemic areas before more sensitive and expensive tests are employed. Besides, Ab-ELISA tests have an advantage of giving the level of antibody titres in the patient’s blood, thus can be used to monitor the progress of the disease treatment. Future research should consider the use and evaluation of more immunogenic components of the cyst fluid or the use of purified or synthetic Ags, in an attempt to increase the test sensitivity.