Population Screening for Urine Antigens to Detect Asymptomatic Subarachnoid Neurocysticercosis: A Pilot Study in Northern Peru

Triplex ELISA for Assessing Durability of Taenia solium Seropositivity after Neurocysticercosis Cure

Neurocysticercosis prevalence estimates often are based on serosurveys. However, assessments of Taenia solium seropositivity durability in patients with various neurocysticercosis types are lacking. We optimized a triplex serologic ELISA by using synthetic GP50, T24H, and Ts18var3 antigens for T. solium. We used that assay to test sequential serologic responses over several years after neurocysticercosis cure in 46 patients, 9 each with parenchymal or ventricular neurocysticercosis and 28 with subarachnoid disease. Triplex results were concordant with 98% of positive and 100% of negative enzyme-linked immunoelectrotransfer blots. Eight years after neurocysticercosis cure, 11.1% of patients with parenchymal, 47.3% with subarachnoid, and 41.7% with ventricular disease were still seropositive. Median time to seroreversion after cure in this cohort in a T. solium nonendemic area was 2 years for parenchymal disease, 4 years for ventricular disease, and 8 years for subarachnoid disease. Our findings can inform epidemiologic models that rely on serosurveys to estimate disease burden.

A Rapid Point-of-Care Assay for Cysticercosis Antigen Detection in Urine Samples

We report a proof-of-concept study using a dipstick assay to detect Taenia solium antigen in urine samples of 30 patients with subarachnoid neurocysticercosis and 10 healthy control subjects. Strips were read in blind by two readers. The assay detected antigen in 29 of 30 cases and was negative in all 10 control samples. Although this study was performed in samples from individuals with subarachnoid neurocysticercosis who likely had high circulating antigen levels, it provides the proof of concept for a functional urine antigen point-of-care assay that detects viable cysts. Such an assay could serve to support a clinical diagnosis of suspect neurocysticercosis or to identify patients at risk of developing severe disease in areas where medical resources are limited, providing evidence to refer these individuals for imaging and specialized care as needed.

Neurocysticercosis: an update on diagnosis, treatment, and prevention

Neurocysticercosis (NCC) is an important cause of neurological disease worldwide, including imported cases in nonendemic countries.

PURPOSE OF REVIEW

The purpose of this review is to update information on diagnosis, management, and prevention of neurocysticercosis.

RECENT FINDINGS

WHO and Infectious Diseases Society of America/American Society of Tropical Medicine and Hygiene guidelines emphasize the importance of corticosteroids and antiparasitic drugs for viable parenchymal disease and single enhancing lesions. Subarachnoid NCC is associated with a high fatality rate unless optimally treated. Advances in subarachnoid NCC include use of prolonged antiparasitic and anti-inflammatory courses and the increasing use of antigen-detection and quantitative PCR assays in diagnosis and follow-up. Emerging data support the safety and efficacy of minimally invasive surgery in ventricular cases. Calcified neurocysticercosis continues to be associated with a high burden of disease. Field studies are demonstrating the feasibility of eradication using a combination of mass chemotherapy for human tapeworms and vaccination/treatment of porcine cysticercosis.

SUMMARY

NCC remains an important and challenging cause of neurological disease with significant morbidity despite advances in treatment and prevention.

Urine 1H-NMR Metabolomics to Discriminate Neurocysticercosis Patients from Healthy Controls: An Exploratory Study

The diagnosis of neurocysticercosis (NCC) is principally based on neuroimaging (magnetic resonance imaging or computed tomography), instrumentation that is scarcely available in the rural regions where Taenia solium transmission, primarily occurs due to poor sanitation conditions. Immunological assays for antigen or antibody detection complement the neuroimaging approach. However, no field-applicable assays to diagnose viable NCC or to guide the referral of cases for neuroimaging or for appropriate management are available. We performed an exploratory study on urine and serum samples using 1H-nuclear magnetic resonance (NMR)-based metabolomics to discriminate NCC patients (n = 14) from healthy control subjects (n = 22). Metabolic profiles demonstrated a discrimination between the urines of NCC patients and noninfected control subjects with a moderate predictive accuracy (R2 = 0.999, Q2 = 0.434). NMR metabolomics analysis has been proven useful in depicting biomarkers linked to other infectious diseases, various types of cancer, and other disorders. Our results, albeit preliminary, open a door to the development of better methods for detecting NCC through the identification of biomarkers participating in disturbed metabolic pathways.

A recombinant monoclonal-based Taenia antigen assay that reflects disease activity in extra-parenchymal neurocysticercosis

BACKGROUND

Antigen tests for diagnosis and disease monitoring in some types of neurocysticercosis (NCC) are useful but access to testing has been limited by availability of proprietary reagents and/or kits.

METHODS/PRINCIPAL FINDINGS

Three previously identified IgM-secreting hybridomas whose IgM products demonstrated specificity to Taenia solium underwent variable heavy and light chain sequencing and isotype conversion to mouse IgG. Screening of these recombinantly expressed IgG anti-Ts hybridomas, identified one (TsG10) with the highest affinity to crude Taenia antigen. TsG10 was then used as a capture antibody in a sandwich antigen detection immunoassay in combination with either a high titer polyclonal anti-Ts antibody or with biotinylated TsG10 (termed TsG10*bt). Using serum, plasma, and CSF samples from patients with active NCC and those from NCC-uninfected patients, ROC curve analyses demonstrated that the TsG10-TsG10-*bt assay achieved a 98% sensitivity and 100% specificity in detecting samples known to be antigen positive and outperformed the polyclonal based assay (sensitivity of 93% with 100% specificity). By comparing levels of Ts antigen (Ag) in paired CSF (n = 10) or plasma/serum (n = 19) samples from well-characterized patients with extra-parenchymal NCC early in infection and at the time of definitive cure, all but 2 (1 from CSF and 1 from plasma) became undetectable. There was a high degree of correlation (r = 0.98) between the Ag levels detected by this new assay and levels found by a commercial assay. Pilot studies indicate that this antigen can be detected in the urine of patients with active NCC.

CONCLUSIONS/SIGNIFICANCE

A newly developed recombinant monoclonal antibody-based Ts Ag detection immunoassay is extremely sensitive in the detection of extra-parenchymal NCC and can be used to monitor the success of treatment in the CSF, serum/plasma and urine. The ability to produce recombinant TsG10 at scale should enable use of this antigen detection immunoassay wherever NCC is endemic.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov Identifiers: NCT00001205 - & NCT00001645.