Added Value of Antigen ELISA in the Diagnosis of Neurocysticercosis in Resource Poor Settings

Abstract

BackgroundNeurocysticercosis (NCC) is the most common cause of acquired epilepsy in Taenia solium endemic areas, primarily situated in low-income countries. Diagnosis is largely based upon the “Del Brutto diagnostic criteria” using the definitive/probable/no NCC diagnosis approach. Neuroimaging and specific T. solium cysticercosis antibody detection results are at the mainstay of this diagnosis, while antigen detection in serum has never been included. This study aimed at evaluating the addition of antigen detection as a major diagnostic criterion, especially in areas where neuroimaging is absent.MethodsThe B158/B60 monoclonal antibody-based enzyme-linked immunosorbent assay (ELISA) for the detection of circulating cysticercus antigen was carried out retrospectively on serum samples collected during a hospital-based study from 83 people with epilepsy (PWE) in an endemic area.ResultsThe addition of antigen results as a major criterion allowed the correct diagnosis of definitive NCC in 10 out of 17 patients as opposed to 0/17 without antigen results in the absence of neuroimaging. A sensitivity of 100% and a specificity of 84% were determined for the diagnosis of active NCC using antigen ELISA. While the use of a higher cutoff improves the specificity of the test to 96%, it decreases its sensitivity to 83%.ConclusionsIn areas where neuroimaging is absent, NCC diagnosis according to the existing criteria is problematic. Taking into account its limitations for diagnosis of inactive NCC, antigen detection can be of added value for diagnosing NCC in PWE by supporting diagnostic and treatment decisions. Therefore, we recommend a revision of the “Del Brutto diagnostic criteria” for use in resource poor areas and suggest the inclusion of serum antigen detection as a major criterion.

The causal relationship between neurocysticercosis infection and the development of epilepsy - a systematic review

“…This can lead to overestimation of NCC prevalence within study populations. More recently, antigen-detecting ELISA assays have been suggested as an improvement over the EITB, as the detection of T. solium antigens instead of antibodies indicates the presence of an established NCC infection, as opposed to exposure only [26]. Serological results are useful as a component of a diagnostic toolbox, but only serve to strengthen a suspected diagnosis, interpreted in a clinical context.…”

Neurocysticercosis in sub-Saharan Africa: a review of prevalence, clinical characteristics, diagnosis, and management

“…A recent study from Tanzania indicated a sensitivity of 100% and a specificity of 84% for diagnosis of active NCC using T. solium cysticercosis antigen ELISA, whereas a study from South Africa demonstrated much lower sensitivity and specificity using the same T. solium cysticercosis antigen ELISA in a different study population. 7,82 Neuroimaging not only is essential for confirmation of diagnosis, but also represents the only method that differentiates between active and inactive disease. Active NCC is defined as the presence of at least one NCC-like cystic lesion (a round shaped hypodensity on cCT with or without a hyperdense dot representing the head of the cysticercus (5scolex) usually no bigger than 1 cm in diameter and without perifocal inflammatory reaction (5oedema)) or at least one ring-or fully enhancing lesion (5granuloma).…”

“…The CT scanner may not be functional anymore or the financial constraints may be too high. An alternative could be the performance of T. solium cysticercosis antigen-ELISA which has been shown to indicate active disease 82 and the course of antigen levels has been suggested as a successful tool to monitor treatment response. 89 In the eastern and southern African region, the T. solium cysticercosis antigen-ELISA has been used for detecting the infection in both pigs and humans.…”

Epilepsy and Neurocysticercosis in Sub-Saharan Africa

“…Although positive results on Taenia solium cysticercosis antigen-ELISA may indicate active disease [131], treatment with antihelminthic medication must not be initiated on the basis of serology alone as cyst stage and presence of oedema cannot be estimated. Oedema can potentially be aggravated by antihelminthic medication resulting in deterioration of the patient's condition and, in the worst case, death may ensue caused by cerebral herniation leading to compression of the brainstem with severe compromise of vital functions.…”