Recent Laboratory Advances in Diagnostics and Monitoring Response to Treatment in Leprosy

An update of the diagnosis, treatment, and prevention of leprosy: A narrative review

Leprosy is an infectious disease that remains a public health concern. It is caused by acid-fast Bacillus leprae, which primarily affects the skin and peripheral nerves, potentially leading to long-term disability and stigma. However, current and previous efforts have focused on developing better diagnostic and therapeutic interventions for leprosy, and its prevention needs to be addressed. In this review, we organize the currently published papers and provide updates on the global epidemiology, diagnosis, treatment, and prevention of leprosy. Several online databases, including MEDLINE (National Library of Medicine, Bethesda, MD), PubMed, EMBASE, Web of Science, and Google Scholar, were searched to collect relevant published papers. As a public health issue, the World Health Organization set the goal of leprosy elimination with a prevalence of <1 case per 10,000 people, which was achieved in 2000 and in most countries by 2010, mainly owing to the treatment of leprosy using drugs starting in 1980 and no-cost access for patients since 1995. Although diagnostic and therapeutic techniques have improved, the new occurrence of leprosy remains a critical global disease burden. With continuous technological improvements in diagnosing and treating leprosy, obtaining more relevant healthcare knowledge and preventing leprosy disability are crucial.

A recombinant chimeric antigen constructed with B-cell epitopes from Mycobacterium leprae hypothetical proteins is effective for the diagnosis of leprosy

The diagnosis if leprosy is difficult, as it requires clinical expertise and sensitive laboratory tests. In this study, we develop a serological test for leprosy by using bioinformatics tools to identify specific B-cell epitopes from Mycobacterium leprae hypothetical proteins, which were used to construct a recombinant chimeric protein, M1. The synthetic peptides were obtained and showed good reactivity to detect leprosy patients, although the M1 chimera have showed sensitivity (Se) and specificity (Sp) values higher than 90.0% to diagnose both paucibacillary (PB) and multibacillary (MB) leprosy patients, but not those developing tegumentary or visceral leishmaniasis, tuberculosis, Chagas disease, malaria, histoplasmosis and aspergillosis, in ELISA experiments. Using sera from household contacts, values for Se and Sp were 100% and 65.3%, respectively. In conclusion, our proof-of-concept study has generated data that suggest that a new recombinant protein could be developed into a diagnostic antigen for leprosy.

New cases of childhood leprosy in two male siblings in low endemic province: an iceberg phenomenon?

Children are the leprosy population most at risk; multibacillary infections are common. We reported pediatric cases with WHO-multibacillary lepromatous type morbus Hansen. We discovered several hypopigmented patches on the right upper arm, anesthesia-filled claw hands, and infiltrates in the ears in one 17- year-old child. In the other case (13-year-old), we discovered reduced sensory sensitivity in nearly every area of the body, infiltrates on the ear, and numerous irregular hypopigmented plaques on the belly, lumbar, and gluteus. Both patients had positive acidfast bacteria. After three months of treatment, multibacillary leprosy patients began to show improvement. Low socioeconomic and environmental conditions, as well as a history of intimate contact with leprosy patients, have been identified as risk factors.

Biosensor-Based Multiple Cross Displacement Amplification for the Rapid Detection of Mycobacterium leprae

Leprosy is an ancient disease caused by Mycobacterium leprae (ML) that remains a public health problem in poverty-stricken areas worldwide. Although many ML detection techniques have been used, a rapid and sensitive tool is essential for the early detection and treatment of leprosy. Herein, we developed a rapid ML detection technique by combining multiple cross displacement amplification (MCDA) with a nanoparticle-based lateral flow biosensor (LFB), termed ML-MCDA-LFB. MCDA induced a rapid isothermal reaction using specific primers targeting the RLEP gene, and the LFB enabled instant visual amplicon detection. The pure genomic DNA of ML and nucleic acids from various pathogens were employed to evaluate and optimize the ML-MCDA-LFB assay. The optimal conditions for ML-MCDA-LFB were 68 °C and 35 min, respectively. The limit of detection for pure ML genomic DNA was 150 fg per vessel, and the specificity of detection was 100% for the experimental strains. Additionally, the entire detection process could be performed within 40 min, including the isothermal amplification (35 min) and result confirmation (1-2 min). Hence, the ML-MCDA-LFB assay was shown to be a rapid, sensitive, and visual method for detecting ML and could be used as a potential tool for early clinical diagnosis and field screening of leprosy.

Highly sensitive and rapid determination of Mycobacterium leprae based on real-time multiple cross displacement amplification

BACKGROUND

Mycobacterium leprae (ML) is the pathogen that causes leprosy, which has a long history and still exists today. ML is an intracellular mycobacterium that dominantly induces leprosy by causing permanent damage to the skin, nerves, limbs and eyes as well as deformities and disabilities. Moreover, ML grows slowly and is nonculturable in vitro. Given the prevalence of leprosy, a highly sensitive and rapid method for the early diagnosis of leprosy is urgently needed.

RESULTS

In this study, we devised a novel tool for the diagnosis of leprosy by combining restriction endonuclease, real-time fluorescence analysis and multiple cross displacement amplification (E-RT-MCDA). To establish the system, primers for the target gene RLEP were designed, and the optimal conditions for E-RT-MCDA at 67 °C for 36 min were determined. Genomic DNA from ML, various pathogens and clinical samples was used to evaluate and optimize the E-RT-MCDA assay. The limit of detection (LoD) was 48.6 fg per vessel for pure ML genomic DNA, and the specificity of detection was as high as 100%. In addition, the detection process could be completed in 36 min by using a real-time monitor.

CONCLUSION

The E-RT-MCDA method devised in the current study is a reliable, sensitive and rapid technique for leprosy diagnosis and could be used as a potential tool in clinical settings.

Suspicious symptom monitoring for leprosy: an optimal practice for early detection under a low endemic situation in Zhejiang Province, China

BACKGROUND

Leprosy is a chronic infectious disease that causes disabilities and deformities. Early detection is a major strategy for leprosy control. This study reported a new practice of suspicious symptom monitoring for early detection of leprosy.

METHODS

A descriptive and comparative analysis between a non-strategy group of pre-implementation of suspicious symptom monitoring in 2005-2011 and a strategy group of strategy implementation in 2012-2018 was conducted through indicators of the number of times of misdiagnoses, delayed period, proportion of early detected cases, and proportion of disabilities.

RESULT

Compared with the non-strategy group in 2005-2011, the median number of times of misdiagnoses was decreased from two times to zero times (z = 4.387, P < 0.001), and the median delayed period of newly detected cases were shortened from 24 months to 13 months (z = 2.381, P < 0.001), the proportion of early detected cases was increased from 43.7% to 75.2% (χ²  = 29.464, P < 0.001), the proportion of grade 2 disabilities was decreased from 28.6% in the highest year of 2005 to 4.0% in the lowest year of 2014, and the average proportion of disabilities was decreased from 33.5% to 17.6% (χ²  = 9.421, P = 0.002) in the strategy group in 2012-2018, respectively.

CONCLUSION

Suspicious symptom monitoring promoted early detection of cases by reducing the number of times misdiagnosis of leprosy patients, shortening the delayed period, increasing the proportion of early detection, and decreasing the proportion of disabilities. It is an important and recommendable public health strategy for leprosy prevention and control in a low epidemic condition.

Leprosy: A Review of Epidemiology, Clinical Diagnosis, and Management

Leprosy is a neglected infectious disease caused by acid-fast bacillus Mycobacterium leprae. It primarily affects the skin and then progresses to a secondary stage, causing peripheral neuropathy with potential long-term disability along with stigma. Leprosy patients account for a significant proportion of the global disease burden. Previous efforts to improve diagnostic and therapeutic techniques have focused on leprosy in adults, whereas childhood leprosy has been relatively neglected. This review aims to update the diagnostic and therapeutic recommendations for adult and childhood leprosy. This review summarizes the clinical, bacteriological, and immunological approaches used in the diagnosis of leprosy. As strategies for the diagnosis and management of leprosy continue to develop better and more advanced knowledge, control and prevention of leprosy are crucial.

Disease burden and current therapeutical status of leprosy with special emphasis on phytochemicals

BACKGROUND

Leprosy (Hansen's disease) is a neglected tropical disease affecting millions of people globally. The combined formulations of dapsone, rifampicin and clofazimine (multidrug therapy, MDT) is only supportive in the early stage of detection, while "reemergence" is a significant problem. There is still a need to develop newer antileprosy molecules either of natural or (semi)synthetic origin.

OBJECTIVE

The review intends to present the latest developments in the disease prevalence, available therapeutic interventions and the possibility of identifying new molecules from phytoextracts.

METHODS

Literature on the use of plant extracts and their active components to treat leprosy was searched. Selected phytoconstituents were subjected to molecular docking study on both wild and mutant types of the Mycobacterium leprae. Since the M. leprae dihydropteroate synthase (DHPS) is not available in the protein data bank (PDB), it was modelled by the homology model method and validated with the Ramachandran plot along with other bioinformatics approaches. Two mutations were introduced at codons 53 (Thr to Ile) and 55 (Pro to Leu) for docking against twenty-five selected phytoconstituents reported from eight plants that recorded effective anti-leprosy activity. The chemical structure of phytochemicals and the standard dapsone structure were retrieved from the PubChem database and prepared accordingly for docking study with the virtual-screening platform of PyRx-AutoDock 4.1.

RESULTS

Based on the docking score (kcal/mol), most of the phytochemicals exhibited a higher docking score than dapsone. Asiaticoside, an active saponin (-11.3, -11.2 and -11.2 kcal/mol), was proved to be the lead phytochemical against both wild and mutant types DHPS. Some other useful phytoconstituents include echinocystic acid (-9.6, -9.5 and -9.5 kcal/mol), neobavaisoflavone (-9.2, -9.0 and -9.0 kcal/mol), boswellic acid (-8.90, -8.90 and -8.90 kcal/mol), asiatic acid (-8.9, -8.8 and -8.9 kcal/mol), corylifol A (-8.8, 8.0, and -8.0), etc. Overall, the computational predictions support the previously reported active phytoextracts of Centella asiatica (L.) Urban, Albizia amara (Roxb.) Boivin, Boswellia serrata Roxb. and Psoralea corylifolia L. to be effective against leprosy.

CONCLUSION

A very small percentage of well-known plants have been evaluated scientifically for antileprosy activity. Further in vivo experiments are essential to confirm anti-leprosy properties of such useful phytochemicals.

Development of a Loop-mediated isothermal amplification (LAMP) technique for specific and early detection of Mycobacterium leprae in clinical samples

Leprosy, a progressive, mutilating and highly stigmatized disease caused by Mycobacterium leprae (ML), continues to prevail in the developing world. This is due to the absence of rapid, specific and sensitive diagnostic tools for its early detection since the disease gets notified only with the advent of physical scarring in patients. This study reports the development of a Loop-mediated isothermal amplification (LAMP) technique for fast, sensitive and specific amplification of 16S rRNA gene of ML DNA for early detection of leprosy in resource-limited areas. Various parameters were optimized to obtain robust and reliable amplification of ML DNA. Blind clinical validation studies were performed which showed that this technique had complete concurrence with conventional techniques. Total absence of amplification of negative control DNA confirmed the specificity of this test. Various visual detection methods viz. colorimetric, turbidity differentiation and bridge flocculation were standardized to establish easy-to-read and rapid diagnosis. This technique eliminates the lack of accuracy and sensitivity in skin smear tests in patients and the requirement for expensive lab equipments and trained technicians. The technique holds promise for further expansion and has the potential to cater to the unmet needs of society for a cheap, highly-sensitive and robust rapid diagnosis of ML.

Insights into Mycobacterium leprae Proteomics and Biomarkers-An Overview

Although leprosy is curable, the identification of biomarkers for the early diagnosis of leprosy would play a pivotal role in reducing transmission and the overall prevalence of the disease. Leprosy-specific biomarkers for diagnosis, particularly for the paucibacillary disease, are not well defined. Therefore, the identification of new biomarkers for leprosy is one of the prime themes of leprosy research. Studying Mycobacterium leprae, the causative agent of leprosy, at the proteomic level may facilitate the identification, quantification, and characterization of proteins that could be potential diagnostics or targets for drugs and can help in better understanding the pathogenesis. This review aims to shed light on the knowledge gained to understand leprosy or its pathogen employing proteomics and its role in diagnosis.