Specificity of immunoblotting analyses in eosinophilic meningitis

Abstract

Angiostrongylus cantonensis and Gnathostoma spinigerum are the two most common causative parasites of eosinophilic meningitis (EOM). Serological tests are helpful tools for confirming the identity of the pathogen. Recent reports determined the specificity of such tests by using normal healthy controls. There have been limited studies done to rule out the cross-reactivity between these two causative parasites of EOM. This study aims to assess the specificity of the serological test in EOM by using each condition as a control for the other. Thirty-three patients with a diagnosis of EOM were enrolled. Sera from 22 patients with a positive 29-kDa antigenic diagnostic band of A. cantonensis were tested for the 21 and 24-kDa antigenic bands of G. spinigerum. Similarly, sera of 11 gnathostomiasis patients were tested for the 29-kDa diagnostic band for A. cantonensis. Only one patient in the angiostrongyliasis group had a positive result for the 21 and 24-kDa antigenic bands of G. spinigerum, while no gnathostomiasis patients showed a positive result for the 29-kDa antigenic band of A. cantonensis. The specificity of the 21 and 24-kDa antigenic bands for gnathostomiasis and the 29-kDa antigenic band for A. cantonensis was 95.5% and 100%, respectively. The antigenic bands for the diagnosis of gnathostomiasis and angiostrongyliasis in EOM were highly specific

A national surveillance of eosinophilic meningitis in Thailand

“…One limitation of this predictive model is that it will be valid only if no preventive intervention is implemented, in which case it may be useful for disease monitoring purposes. We also did not examine any causal relationship between EOM and other factors ( Sawanyawisuth et al, 2020 , Sawanyawisuth et al, 2011 , Sawanyawisuth et al, 2012 , Sawanyawisuth et al, 2010 ; Tongdee et al, 2021 ). Finally, unreported or undiagnosed EOM cases will be missed using retrieved data from the database.…”

Eosinophilic meningitis caused by Angiostrongylus cantonensis in an infant

“…However, the diagnosis of A cantonensis in clinically suspected patients should not be excluded on the basis of negative CSF test results. [ 8 ] Recent research found that CSF eosinophil counts of 40% or higher are significantly predictive for positive serologic tests. [ 9 ] Although the CSF eosinophil levels of most previous infant cases were higher than 40%, [ 1 – 3 ] the diagnosis of A cantonensis should not be excluded on the basis of absent CSF eosinophilia.…”

A filtration-based rapid test using a partially purified third-stage larval antigen to detect specific antibodies for the diagnosis of gnathostomiasis

“…All patients were confirmed by immunoblotting for the detection of the G. spinigerum -specific 24-kDa band. This G. spinigerum 24-kDa-antigen-based immunoblot showed 100% specificity (Tapchaisri et al ., 1991; Anantaphruti et al ., 2005; Laummaunwai et al ., 2007; Sawanyawisuth et al ., 2011). Thus, these 28 clinical gnathostomiasis patients represented true infections, and the evaluation of sensitivity is therefore accurate in the present study.…”

“…However, the availability of specific antigens remains a major issue for developing serodiagnostic tests, particularly in non-endemic areas. Immunoblot analysis for the detection of the G. spinigerum -specific 24-kDa band is the most widely used method to confirm a clinical diagnosis with 100% specificity (Tapchaisri et al ., 1991; Anantaphruti et al ., 2005; Sawanyawisuth et al ., 2011). However, the immunoblot method is labour-intensive and time-consuming because it requires sophisticated instruments and well-trained operators.…”