Paired serum and CSF samples were obtained from 91 patients with neurocysticercosis (NCC) for detection of Taenia solium (TS) antibodies and antigens, in a study at centers in Lima, Peru, Belgium, and the USA. TS antibodies were detected using an enzyme-linked immunotransfer blot (EITB) assay, and antigens, using a monoclonal antibody-based enzyme-linked immunosorbent assay (ELISA). NCC was intraparenchymal in 48 and extraparenchymal in 43 patients. For the intraparenchymal NCC group, the EITB antibody assay yielded more true positive results on serum samples, whereas the ELISA antigen assay yielded slightly more positive results for CSF samples (differences not significant). Patients with calcified NCC were antibody positive and antigen negative. For extraparencymal disease, all samples were antibody positive, and all but 2 were antigen positive, mostly with high antigen levels. [1]

COMMENT. The authors conclude that the EITB antibody-detecting assay is equally sensitive on serum and CSF samples. The ELISA assay for antigen detection is more sensitive when performed on CSF samples than serum, but less sensitive than the EITB assay. ELISA, using either serum or CSF samples, is better than EITB in the differentiation of active and inactive NCC. High antigen levels detected by ELISA suggest the presence of subarachnoid NCC, associated with a worse prognosis.

Since neuroimaging is often nonspecific for NCC, immunodiagnosis is usually necessary for confirmation. CSF samples offer no advantage over serum for detection of antibodies by EITB assay. In intraparenchymal cases, although the use of CSF samples for antigen detection by ELISA assay may yield a 13% increase in case identification, the increase over serum samples is not significant. With extraparenchymal disease, most patients are strongly seropositive by EITB assay on either serum or CSF.

The findings in the above study suggest that serum antibody detection by an EITB assay, using purified antigen, is the assay of choice for diagnosis of NCC.