A lateral flow assay (LFA) for the rapid detection of extraparenchymal neurocysticercosis using cerebrospinal fluid

Crucial role of biosensors in the detection of helminth biomarkers in public health programmes

Helminthiases are highly prevalent but neglected infections that affect more than 1·5 billion people worldwide. Considering the worldwide prevalence of helminthiases, WHO has declared them a public health concern since 2001, necessitating rigorous control and elimination efforts. However, only a few reliable point-of-care diagnostic tests are available for assessing the effectiveness of public health interventions targeting helminthiases, thus increasing the risk of suboptimal outcomes, misallocation of resources, and emergence of drug-resistant helminths. This Review provides an introduction on helminthiases and strategies to achieve control, elimination, interruption in transmission, and eradication of these infections. The Review then comprehensively details the existent biosensors that can be used to detect these infections in human samples, focusing on their target biomarkers, the bioreceptors used, and the sensing readouts. The Review concludes with an in-depth discussion on the persistent challenges related to helminthiases, aiming to encourage the development of much-needed diagnostics specific to these neglected infections.

Tutorial: design and fabrication of nanoparticle-based lateral-flow immunoassays

Lateral-flow assays (LFAs) are quick, simple and cheap assays to analyze various samples at the point of care or in the field, making them one of the most widespread biosensors currently available. They have been successfully employed for the detection of a myriad of different targets (ranging from atoms up to whole cells) in all type of samples (including water, blood, foodstuff and environmental samples). Their operation relies on the capillary flow of the sample throughout a series of sequential pads, each with different functionalities aiming to generate a signal to indicate the absence/presence (and, in some cases, the concentration) of the analyte of interest. To have a user-friendly operation, their development requires the optimization of multiple, interconnected parameters that may overwhelm new developers. In this tutorial, we provide the readers with: (i) the basic knowledge to understand the principles governing an LFA and to take informed decisions during lateral flow strip design and fabrication, (ii) a roadmap for optimal LFA development independent of the specific application, (iii) a step-by-step example procedure for the assembly and operation of an LF strip for the detection of human IgG and (iv) an extensive troubleshooting section addressing the most frequent issues in designing, assembling and using LFAs. By changing only the receptors, the provided example procedure can easily be adapted for cost-efficient detection of a broad variety of targets.

Thermographic detection and quantification of THC in oral fluid at unprecedented low concentrations

With recent changes in the legalization of cannabis around the world, there is an urgent need for rapid, yet sensitive, screening devices for testing drivers and employees under the influence of cannabis at the roadside and at the workplace, respectively. Oral fluid lateral flow immunoassays (LFAs) have recently been explored for such applications. While LFAs offer on-site, low-cost and rapid detection of tetrahydrocannabinol (THC), their nominal detection threshold is about 25 ng/ml, which is well above the 1-5 ng/ml per se limits set by regulations. In this paper, we report on the development of a thermo-photonic imaging system that utilizes the commercially available low-cost LFAs but offers detection of THC at unprecedented low concentrations. Our reader technology examines photothermal responses of gold nanoparticles (GNPs) in LFA through lock-in thermography (LIT). Our results (n = 300) suggest that the demodulation of localized surface plasmon resonance responses of GNPs captured by infrared cameras allows for detection of THC concentrations as low as 2 ng/ml with 96% accuracy. Quantification of THC concentration is also achievable with our technology through calibration.

Systematic Review and Meta-Analysis of Management Strategies and Outcomes in Adult Spinal Neurocysticercosis

OBJECTIVE

Spinal involvement in neurocysticercosis is rare and can lead to debilitating injury if not diagnosed and treated early. We aim to provide the reader with a thorough analysis of the best available evidence regarding patient characteristics, optimal treatment modality, and outcomes in cases of spinal neurocysticercosis.

METHODS

A systematic review of the literature using PubMed, Google Scholar, and Web of Science electronic databases was made according to the PRISMA guidelines. An illustrative case of intramedullary-cervical spinal disease is also presented for illustrative purposes.

RESULTS

A total of 46 reports of 103 patients fitting the screening criteria were identified. Isolated spinal involvement was seen in 46.15% of patients. Most infections (76.92%) had an intradural extramedullary localization, with 43.27% of cases involving >1 spinal cord level. The most common presenting symptoms were motor deficits (77.88%), pain syndromes (64.42%), and sensory deficits (53.85%). Combined surgical resection and pharmacologic therapy was the most frequently used treatment modality (49.04%) and had the highest proportion of patients reporting symptomatic improvement at follow-up (78.43%). Combination therapy had a significantly higher rate of neurologic recovery compared with surgery alone (P = 0.004) or medical treatment (P = 0.035).

CONCLUSIONS

Spinal involvement in neurocysticercosis should be considered in patients from or who traveled to endemic areas presenting with ring-enhancing lesions. Combined treatment with surgery followed by cysticidal and steroid medication seems to be superior to surgery or medical treatment in isolation and seems to provide the highest chances of recovery.

Progress on the development of rapid diagnostic tests for foodborne neglected zoonotic helminthiases: A systematic review

BACKGROUND

Foodborne Neglected Zoonotic Helminths (FNZH) are parasites of both economic and public health importance. They include Taenia solium, Echinococcus granulosus sensu lato, Echinococcus multilocularis and Foodborne trematodes (FBT). FNZH are earmarked for major interventions for control, elimination and eradication. This systematic review highlights the progress towards development of rapid tests for the diagnosis of FNZH since 2010 when they were listed as neglected tropical diseases.

METHODOLOGY

A systematic search was conducted in three databases, World of Science, Embase and PubMed using the same search phrase. The search produced 480 hits. Three studies from back referencing were included. Only 22 of these met the inclusion criteria. Data was extracted from these and presented qualitatively.

RESULTS

Twenty-five rapid diagnostic tests were found to have been developed since 2010, eight for diagnosis of T. solium infections, eight for echinococcosis and nine for FBT infections. The rapid tests for diagnosing T. solium infections included six antibody detecting and two antigen detecting tests. They constitute a combination among them, with some tests providing qualitative, others quantitative results. Similarly, seven out of the eight rapid tests developed for Echinococcus infections were antibody detecting tests save for one loop mediated isothermal amplification test. All of them were qualitative tests. For FBT infections, nine rapid tests were described; two antibody and one nucleic acid detecting test for diagnosis of Fascioliasis; three nucleic acid detecting tests for Opisthorchiasis; one antibody detecting test for Paragonimiasis; and for Clonorchiasis, one antibody and one nucleic acid detecting test. The FBT infection rapid tests were all qualitative in nature. Most of these tests have not undergone field evaluation in endemic areas where they will be used most.

CONCLUSION

This review describes the development and evaluation of rapid diagnostic tests, while highlighting the need for in depth validations of the tools to determine how well they can perform in endemic areas.

New guidelines for the diagnosis and treatment of neurocysticercosis: a difficult proposal for patients in endemic countries

INTRODUCTION

Recent guidelines for the diagnosis and treatment for neurocysticercosis (NC) from the Infectious Disease Society of America/American Society of Tropical Medicine and Hygiene were developed to be used in the United States and Canada, where only a small fraction of NC cases occur. Areas covered: The paper discusses the strengths and weakness of the proposed guidelines. Expert commentary: Although these new guidelines bring much needed attention to a neglected parasitic disease, some of the recommendations made are based on insufficient and/or inadequate evidence. The authors only recommend one specific immunological assay for use in the diagnosis of NC, when evidence clearly supports other options. The authors strongly recommend dual-anthelminthic for patients with multiple active parenchymal cysts on the basis of one clinical trial that was stopped early. The authors recommend surgical removal of cysts in the fourth ventricle and long-term treatment for subarachnoid NC despite their own admission that there is little evidence to support these recommendations. We propose that clinicians should approach some of the recommendations in the new guidelines with caution and call for the establishment of gold-standard guidelines that can be used and adapted for the diagnosis and treatment of patients with NC worldwide.

Reciprocal contribution of clinical studies and the HP10 antigen ELISA for the diagnosis of extraparenchymal neurocysticercosis

To evaluate diagnosis of active neurocysticercosis, paired cerebral spinal fluid (CSF) and serum samples from 24 neurocysticercosis (NCC) patients and 17 control neurological patients were assayed in the HP10 Taenia antigen (Ag) ELISA. The CSF samples were also tested with an HP10 Lateral Flow Assay (LFA). The HP10 Ag was detected by ELISA in the CSF of 5/5 patients with Definitive extraparenchymal NCC, and in 4/5 of the corresponding sera. In the Definitive parenchymal group, on the other hand, the HP10 Ag was absent in 2/3 CSF (with a very low value in the one positive sample) and all the corresponding serum samples. Samples of CSF from 4/7 patients in the Probable parenchymal group, were also significantly HP10 Ag positive, suggesting the presence of extraparenchymal cysts not identified by the imaging studies. With the possible exception of one patient, the corresponding serum samples of the Probable parenchymal NCC group, were all HP10 Ag negative. Samples of CSF from 9 NCC patients diagnosed with Mixed parenchymal and extraparenchymal NCC were all significantly HP10 Ag positive, confirming the presence of extraparenchymal cysts, with only 7/9 of the corresponding serum samples being HP10 positive. Thus detection of the HP10 Ag indicates extraparenchymal and not parenchymal cyst localization and is more sensitive with CSF than serum. Three neurological patients clinically diagnosed as subarachnoid cyst, hydrocephalus and tuberculoma, respectively, were clearly positive for HP10 Ag. Of these, two were confirmed as NCC by subsequent imaging; the third died prior to further examination. Thus, a total of 8 patients had their clinical diagnosis questioned. Finally, there was good agreement between the HP10 Ag ELISA and LFA with CSF samples giving an optical density ≥0.4 in the ELISA assay. In conclusion, the HP10 Ag assay should provide a valuable and reciprocal tool in the clinical diagnosis and follow up of extraparenchymal NCC.

Neurocysticercosis infection and disease-A review

Neurocysticercosis (NCC) is the most common parasitic disease of the human central nervous system (CNS), a pleomorphic disease with a diverse array of clinical manifestations. The infection is pleomorphic and dependent on a complex range of interconnecting factors, including number and size of the cysticerci, their stage of development and localisation within the brain with resulting difficulties in accurate diagnosis and staging of the disease. This review examines the factors that contribute to the accurate assessment of NCC distribution and transmission that are critical to achieving robust disease burden calculations. Control and prevention of T. solium transmission should be a key priority in global health as intervention can reduce the substantial healthcare and economic burdens inflicted by both NCC and taeniasis. Surveillance systems need to be better established, including implementing obligatory notification of cases. In the absence of reliable estimates of its global burden, NCC will remain-along with other endemic zoonoses, of low priority in the eyes of funding agencies-a truly neglected disease.