Acta Tropica 110 (2009) 38–45 Contents lists available at ScienceDirect Acta Tropica journal homepage: www.elsevier.com/locate/actatropica Evaluation of an IgG-ELISA strategy using Taenia solium metacestode somatic and excretory–secretory antigens for diagnosis of neurocysticercosis revealing biological stage of the larvae Priyadarshi Soumyaranjan Sahu a,c,∗ , Subhash Chandra Parija a , Sunil K. Narayan b , Debendra Kumar d a Department of Microbiology, Jawaharlal Institute of Postgraduate Medical Education and Research, Pondicherry 605006, India b Department of Neurology, Jawaharlal Institute of Postgraduate Medical Education and Research, Pondicherry 605006, India c Department of Microbiology, Alluri Sitarama Raju Academy of Medical Sciences, Eluru, Andhra Pradesh 534005, India d Department of Parasitology, Rajiv Gandhi College of Veterinary and Animal Sciences, Pondicherry 605009, India article info Article history: Received 31 March 2008 Received in revised form 30 December 2008 Accepted 2 January 2009 Available online 9 January 2009 Keywords: Neurocysticercosis Taenia solium Metacestode Excretory secretory IgG-ELISA abstract Diagnosis of neurocysticercosis (NCC) is complicated because of the variability in clinical presentations and course of the disease where viability of parasite is a major determinant. The present study describes evaluation of ELISAs using Taenia solium metacestode somatic and excretory–secretory (ES) antigens for detection of anti-T. solium metacestode IgG antibodies in serum and cerebrospinal fluid (CSF). And results of the ELISAs in cases with a definitive diagnosis of NCC are correlated with the biological stages of the parasite such as live vesicular or degenerated stage. The sensitivity of the IgG-ELISA using ES antigen is observed to be much higher in serum (88.2%) than in CSF (64.28%) although it is only marginally higher in serum (76.4%) than in CSF (75%) when somatic antigen is used in the ELISA. Whereas, the specificities of the ELISA using either somatic or ES antigen for detection of IgG antibodies in serum (97.97%; 96.96%) and CSF (96.42%; 97.61%) are comparable. A strong association is observed between live stage of the parasite and detection of antibodies in sera and CSF from more number of NCC patients by ELISA using ES antigens. Similarly, detection of antibodies by ELISA using somatic antigens could be associated with the dead or degenerated stage of the parasite in brain. The IgG-ELISA strategy developed in the present study opens up an avenue for diagnosis of NCC in hospitals or in population prevalence studies. The use of crude extracts of ES proteins might improve the serodiagnosis of the cases of NCC carrying live vesicular stage of the parasite larvae. © 2009 Elsevier B.V. All rights reserved. 1. Introduction Neurocysticercosis (NCC), caused by Taenia solium metacestode larvae in central nervous system (CNS), is a major health problem in developing countries and it affects patients of all ages (Del Brutto et al., 2001). This disease not only causes neurological morbidity but also imposes economic hardships on impoverished populations (Rajshekhar et al., 2003). In a recent report on the seroprevalence study in seizure-free subjects from a south Indian province, anti- T. solium metacestode antibodies were noted in 15.9% people and were significantly higher in the rural population (17.7%) compared with the urban population (6.0%) where only 8% of the total seropos- itive cases had a history of NCC (Prabhakaran et al., 2008). Similarly, in an earlier study from north India, the prevalence of anti-T. solium ∗ Corresponding author at: Department of Microbiology, Alluri Sitarama Raju Academy of Medical Sciences, Eluru, Andhra Pradesh 534005, India. Tel.: +91 8812 249 362x378. E-mail address: priyadarshi sahu@yahoo.com (P.S. Sahu). metacestode antibodies in different population groups was found to be 17.3% with highest prevalence (24%) reported from slum areas followed by that of rural areas (20%) and least (8%) in the urban orga- nized sectors (Khurana et al., 2006). However, the actual prevalence picture is yet to be figured. The live vesicular stage is the first stage of T. solium metaces- tode in parenchyma of the brain, with live parasite producing little or no inflammatory response in the surrounding tissue. The para- site may continue to remain in this stage for years or may undergo degeneration as a result of the host’s immune response. The col- loidal vesicular stage is next stage in which, the parasite begins to degenerate, and the scolex shows the signs of hyaline degeneration, associated with gradual shrinkage of its size. The cyst fluid becomes turbid and the cyst wall becomes thicker. The third stage is the granular nodular stage, in which the wall of T. solium metacestode is thickened and the scolex is transformed to a coarse mineralized granule. Surrounding edema regress gradually. The final stage is the nodular calcified stage, in which the lesion is shrunk to one half or one quarter of its original size and is completely calcified. No sur- rounding edema is appreciated in this stage (Zee et al., 2000). It is 0001-706X/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.actatropica.2009.01.002