title: Parasite antigen in serum predicts the presence of viable brain parasites in patients with apparently calcified cysticercosis only.
abstract: BACKGROUND
  Computed tomography (CT) remains the standard neuroimaging screening exam for neurocysticercosis, and residual brain calcifications are the commonest finding. Magnetic resonance imaging (MRI) is more sensitive than CT but is rarely available in endemic regions. Enzyme-linked immunoelectrotransfer blot (EITB) assay uses antibody detection for diagnosis confirmation; by contrast, enzyme-linked immunosorbent assay (ELISA) antigen detection (Ag-ELISA) detects circulating parasite antigen. This study evaluated whether these assays predict undetected viable cysts in patients with only calcified lesions on brain CT.
  
  
  METHODS
  Serum samples from 39 patients with calcified neurocysticercosis and no viable parasites on CT were processed by Ag-ELISA and EITB. MRI was performed for each patient within 2 months of serologic testing. Conservatively high ELISA and EITB cutoffs were used to predict the finding of viable brain cysts on MRI.
  
  
  RESULTS
  Using receiver operating characteristic-optimized cutoffs, 7 patients were Ag-ELISA positive, and 8 had strong antibody reactions on EITB. MRI showed viable brain cysts in 7 (18.0%) patients. Patients with positive Ag-ELISA were more likely to have viable cysts than Ag-ELISA negatives (6/7 vs 1/32; odds ratio, 186 [95% confidence interval, 1-34 470.0], P < .001; sensitivity 85.7%, specificity 96.9%, positive likelihood ratio of 27 to detect viable cysts). Similar but weaker associations were also found between a strong antibody reaction on EITB and undetected viable brain cysts.
  
  
  CONCLUSIONS
  Antigen detection, and in a lesser degree strong antibody reactions, can predict viable neurocysticercosis. Serological diagnostic methods could identify viable lesions missed by CT in patients with apparently only calcified cysticercosis and could be considered for diagnosis workup and further therapy.
authors.affiliation: School of Medicine.
authors.forename: Alonso
authors.initials: A
authors.lastname: Zea-Vera
authors.forename: Erika G
authors.initials: EG
authors.lastname: Cordova
authors.forename: Silvia
authors.initials: S
authors.lastname: Rodriguez
authors.forename: Isidro
authors.initials: I
authors.lastname: Gonzales
authors.forename: E Javier
authors.initials: EJ
authors.lastname: Pretell
authors.forename: Yesenia
authors.initials: Y
authors.lastname: Castillo
authors.forename: Sheila
authors.initials: S
authors.lastname: Castro-Suarez
authors.forename: Sarah
authors.initials: S
authors.lastname: Gabriël
authors.forename: Victor C W
authors.initials: VC
authors.lastname: Tsang
authors.forename: Pierre
authors.initials: P
authors.lastname: Dorny
authors.forename: Hector H
authors.initials: HH
authors.lastname: Garcia
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000947:Antigens, Helminth / Q000097:blood*; D001921:Brain / Q000469:parasitology*; D002114:Calcinosis; D003551:Cysticercosis / Q000097:blood* / Q000469:parasitology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D020019:Neurocysticercosis / Q000097:blood* / Q000175:diagnosis / Q000469:parasitology*
chemical_list: D000947:Antigens, Helminth
keywords: Peru; antigen detection; calcifications; epilepsy; neurocysticercosis