Lack of specificity of a single positive 50-kDa band in the electroimmunotransfer blot (EITB) assay for cysticercosis

ABSTRACTDiagnosis of the parasitic infection cysticercosis is usually confirmed by serological assays. The electroimmunotransfer blot (EITB) for cysticercosis is a sensitive and specific assay, which uses six glycoprotein antigens on a strip to detect antibodies to Taenia solium cysticerci. Although the appearance of bands at any of these six sites is considered to be a positive result, a growing body of evidence suggests that the presence of a single 50-kDa band in this assay may not indicate infection. An audit of 984 samples tested over a 3-year period showed that only two (15.4%) of 13 samples with a single 50-kDa band were associated with a diagnosis of cysticercosis. Possible reasons for this include technical problems, cross-reactivity with other parasites or other diseases, or the presence of a non-specific band. The results suggest that the finding of a single 50-kDa band should be interpreted with caution.