Molecular, immunological and neurophysiological evaluations for early diagnosis of neural impairment in seropositive leprosy household contacts

Description of electroneuromiographic and laboratorial findings in leprosy neuropathy, according to its clinical forms: the confirmation of a spectral disease

Introduction

Leprosy is one of the most common infectious cause of peripheral neuropathy in the world and can lead to sequelae and physical disabilities. Electroneuromyography (ENMG) is the gold-standard test for evaluating neural impairment, detecting from subclinical abnormalities to advanced lesions. This study aims to describe the electroneuromyographic findings in patients with leprosy, according to their clinical forms.

Methods

The study is a retrospective observational analysis of the medical records of patients with leprosy, of a National Reference Center of Sanitary Dermatology and Leprosy in Brazil between 2014 and 2022. 513 patients underwent ENMG at leprosy diagnosis and also underwent a clinical, serological and molecular evaluation of the disease.

Results

The electroneuromyographic findings showed 2,671 altered nerves, with an average of 6.9 (±5.1) altered nerves per patient. The most affected sensory nerves were the superficial peroneal (25.0%; 413/1649), sural (15.1%; 397/2627) and ulnar (13.8%; 363/2627), with average of 4.3 (±3.2) affected sensory nerves per patient. The most affected motor nerves were the ulnar (33.1%; 338/1022) and common peroneal (12.1%; 319/2627), with average of 2.6 (±2.5) motor nerves affected per patient. 126 patients presented normal ENMG and, among the 387 with abnormalities in the exam, 13.2% (51/387) had mononeuropathy and 86.8% (336/387) had multiple mononeuropathy. Axonal involvement was more frequent in primary neural leprosy, borderline-tuberculoid, borderline-lepromatous and lepromatous forms.

Discussion

Our findings support that leprosy is a spectral disease, characterized by a balance between host immunity and bacillary load. Therefore, the impairment and electroneuromyographic characteristics are distinct and may vary according to the clinical form.

High-resolution ultrasonography for early diagnosis of neural impairment in seropositive leprosy household contacts

Leprosy household contacts (HC) represent a high-risk group for the development of the disease. Anti-PGL-I IgM seropositivity also increases the risk of illness. Despite significant advances in leprosy control, it remains a public health problem; and early diagnosis of this peripheral neuropathy represents one of the main goals of leprosy programs. The present study was performed to identify neural impairment in leprosy HC by analyzing differences in high-resolution ultrasonographic (US) measurements of peripheral nerves between leprosy HC and healthy volunteers (HV). Seventy-nine seropositive household contacts (SPHC) and 30 seronegative household contacts (SNHC) underwent dermato-neurological examination and molecular analysis, followed by high-resolution US evaluation of cross-sectional areas (CSAs) of the median, ulnar, common fibular and tibial nerves. In addition, 53 HV underwent similar US measurements. The US evaluation detected neural thickening in 26.5% (13/49) of the SPHC and only in 3.3% (1/30) among the SNHC (p = 0.0038). The CSA values of the common fibular and tibial nerves were significantly higher in SPHC. This group also had significantly greater asymmetry in the common fibular and tibial nerves (proximal to the tunnel). SPHC presented a 10.5-fold higher chance of neural impairment (p = 0.0311). On the contrary, the presence of at least one scar from the BCG vaccine conferred 5.2-fold greater protection against neural involvement detected by US (p = 0.0184). Our findings demonstrated a higher prevalence of neural thickening in SPHC and support the role of high-resolution US in the early diagnosis of leprosy neuropathy. The combination of positive anti-PGL-I serology and absence of a BCG scar can identify individuals with greater chances of developing leprosy neuropathy, who should be referred for US examination, reinforcing the importance of including serological and imaging methods in the epidemiological surveillance of leprosy HC.

Early diagnosis of neural impairment in seropositive leprosy household contacts: The experience of a reference center in Brazil

Introduction

Leprosy is an infectious disease that remains with a high number of new cases in developing countries. Household contacts have a higher risk for the development of the disease, but the neural impairment in this group is not well elucidated yet. Here, we measured the chance of occurrence of peripheral neural impairment in asymptomatic leprosy household.

Methods

Contacts who present anti-PGL-I IgM seropositivity, through electroneuromyography (ENMG) evaluation. We recruited 361 seropositive contacts (SPC) from 2017 to 2021, who were subjected to an extensive protocol that included clinical, molecular, and electroneuromyographic evaluations.

Results

Our data revealed a positivity of slit skin smear and skin biopsy qPCR of 35.5% (128/361) and 25.8% (93/361) respectively. The electroneuromyographic evaluation of the SPC showed neural impairment in 23.5% (85/361), with the predominance of a mononeuropathy pattern in 62.3% (53/85). Clinical neural thickening was observed in 17.5% (63/361) of seropositive contacts, but among the individuals with abnormal ENMG, only 25.9% (22/85) presented neural thickening in the clinical exam.

Discussion

Ours results corroborates the need to make the approach to asymptomatic contacts in endemic countries more timely. Since leprosy in its early stages can present an indolent and subclinical evolution, serological, molecular, and neurophysiological tools are essential to break the disease transmission chain.

Silent peripheral neuropathy determined by high-resolution ultrasound among contacts of patients with Hansen's disease

Introduction

Hansen's disease (HD) primarily infects peripheral nerves, with patients without HD being free of peripheral nerve damage. Household contacts (HHCs) of patients with HD are at a 5-10 times higher risk of HD than the general population. Neural thickening is one of the three cardinal signs that define a case of HD according to WHO guidelines, exclusively considering palpation examination that is subjective and may not detect the condition in the earliest cases even when performed by well-trained professionals. High-resolution ultrasound (HRUS) can evaluate most peripheral nerves, a validated technique with good reproducibility allowing detailed and accurate examination.

Objective

This study aimed to use the peripheral nerve HRUS test according to the HD protocol as a diagnostic method for neuropathy comparing HHCs with healthy volunteers (HVs) and patients with HD.

Methods

In municipalities from 14 different areas of Brazil we selected at random 83 HHC of MB-patients to be submitted to peripheral nerve ultrasound and compared to 49 HVs and 176 HD-patients.

Results

Household contacts assessed by HRUS showed higher median and mean absolute peripheral nerve cross-sectional area (CSA) values and greater asymmetries (ΔCSA) compared to HVs at the same points. Median and mean absolute peripheral nerve CSA values were higher in patients with HD compared to HCCs at almost all points, while ΔCSA values were equal at all points. Mean ± SD focality (ΔTpT) values for HHCs and patients with HD, respectively, were 2.7 ± 2.2/2.6 ± 2.2 for the median nerve, 2.9 ± 2.7/3.3 ± 2.9 for the common fibular nerve (p > 0.05), and 1.3 ± 1.3/2.2 ± 3.9 for the ulnar nerve (p < 0.0001).

Discussion

Considering HRUS findings for HHCs, asymmetric multiple mononeuropathy signs (thickening or asymmetry) in at least 20% of the nerves evaluated could already indicates evidence of HD neuropathy. Thus, if more nerve points are assessed in HHCs (14 instead of 10), the contacts become more like patients with HD according to nerve thickening determined by HRUS, which should be a cutting-edge tool for an early diagnosis of leprosy cases.

Clinical, epidemiological, and laboratory prognostic factors in patients with leprosy reactions: A 10-year retrospective cohort study

Introduction

Leprosy reactions, the main cause of neural damage, can occur up to 7 years after starting multidrug therapy. We aimed to approach the prognostic factors that may influence the leprosy reactions over the follow-up time.

Methods

Retrospective cohort study, encompassing 10 years of data collection, composed of 390 patients, divided into 201 affected by reactions and 189 reaction-free individuals. Epidemiological, clinical, and laboratory variables were approached as prognostic factors associated with leprosy reactions. The association among variables was analyzed by a binomial test and survival curves were compared by the Kaplan-Meier and Cox proportional-hazards regression.

Results

51.5% (201/390) of patients were affected by leprosy reactions. These immunological events were associated with lepromatous leprosy (16.2%; 63/390; p < 0.0001) and multibacillary group (43%; 169/390; p < 0.0001). This study showed that survival curves for the prognostic factor anti-PGL-I, comparing positive and negative cases at diagnosis, differed in relation to the follow-up time (Log Rank: p = 0.0760; Breslow: p = 0.0090; Tarone-Ware: p = 0.0110). The median survival times (time at which 50% of patients were affected by leprosy reactions) were 5 and 9 months for those reactional cases with negative (26/51) and positive serology (75/150), respectively. The time-dependent covariates in the cox proportional-hazards regression showed anti-PGL-I as the main prognostic factor to predict leprosy reactions (hazard ratio=1.91; p = 0.0110) throughout the follow-up time.

Conclusions

Finally, these findings demonstrated that anti-PGL-I serology at diagnosis is the most important prognostic factor for leprosy reactions after starting multidrug therapy, thus enabling prediction of this immunological event.

Factors associated with the development of leprosy in Brazilian contacts: a systematic review

People who interact with leprosy patients in their environment, neighborhood, family, or social relationships are at risk to develop the disease. This systematic review investigated the risk and protective factors associated with the development of leprosy in Brazilian contacts. The studies were found in Cochrane Library, PubMed (MEDLINE), Embase, Virtual Health Library, grey literature and hand search until July 2021. The study selection, data extraction and quality assessment were independently performed by two investigators. The quality assessment was performed using the Newcastle-Ottawa Scale (NOS). This review was registered in PROSPERO (CRD42020160680). Seventeen articles fulfilled the inclusion criteria (n=544). The immunological and molecular factors, such as Anti-phenolic Glycolipid Antibodies (Anti-PGL-1) seropositivity, negative Mitsuda test, absence of Bacillus Calmette-Guérin (BCG) scar, positive Polymerase Chain Reaction (PCR) in blood; age and race; conviviality, education, contact time and type of contact, as well as elements related to the index case (bacilloscopic index; genetic conditions, family relationships), and some combined factors were shown to be relevant risk factors associated with the development of the disease in Brazilian leprosy contacts. The protective factors reported were the presence of one or more BCG scars, positive Mitsuda test, and education level. All selected studies were considered of high quality according to NOS. The knowledge of disease-related risk and protective factors provides the scientific basis for decision-making in the management of the disease in leprosy contacts.

Primary neural leprosy: clinical, neurophysiological and pathological presentation and progression

Disability in leprosy is a direct consequence of damage to the peripheral nervous system which is usually worse in patients with no skin manifestations, an underdiagnosed subtype of leprosy known as primary neural leprosy. We evaluated clinical, neurophysiological and laboratory findings of 164 patients with definite and probable primary neural leprosy diagnoses. To better understand the disease progression and to improve primary neural leprosy clinical recognition we compared the characteristics of patients with short (≤ 12 months) and long (> 12 months) disease duration. Positive and negative symptoms mediated by small-fibre were frequent at presentation (∼95%), and symptoms tend to manifest first in the upper limbs (∼68%). There is a consistent phenotypic variability between the aforementioned groups. Deep sensory modalities were spared in patients evaluated within the first 12 months of the disease, and were only affected in patients with longer disease duration (∼12%). Deep tendon reflexes abnormalities were most frequent in patients with longer disease duration (p < 0,001), as well as motor deficits (p = 0,002). Damage to large fibres (sensory and motor) is a latter event in primary neural leprosy. Grade-2 disability and nerve thickening was also more frequent in cases with long disease duration (p < 0,001). Primary neural leprosy progress over time and there is a marked difference in clinical phenotype between patients with short and long disease duration. Patients assessed within the first 12 months of symptom onset had a non-length-dependent predominant small-fibre sensory neuropathy, whilst patients with chronic disease presented an asymmetrical all diameter sensory-motor neuropathy and patchily decreased/absent deep tendon reflexes.

Peripheral nerve biopsy: a tool still needed in the early diagnosis of neural leprosy?

BACKGROUND

The early recognition of neural impairment in leprosy, especially in primary neural forms, represents a challenge in clinical practice and a peripheral nerve biopsy may be required for diagnostic confirmation. This study aims to characterize the epidemiological, clinical, electroneuromyographic, laboratory and histopathological aspects of patients undergoing peripheral nerve biopsy during investigation of primary neural cases in leprosy.

METHODS

A total of 104 patients with peripheral neuropathy who were referred to a national reference centre for leprosy were biopsied from 2014 to 2018. All cases underwent clinical, laboratory, histopathological and electroneuromyographic evaluations.

RESULTS

Of 104 biopsied patients, leprosy was confirmed in 89.4% (93/104). The biopsied nerves were the ulnar (67.8% [63/93]), superficial fibular (21.5% [20/93]), sural (8.6% [8/93]), radial (1.1% [1/93]) and deep fibular (1.1% [1/93]). Twenty-nine percent (27/93) presented histopathological abnormalities and 4.4% (4/93) presented acid-fast bacilli. Nerve and superjacent skin quantitative polymerase chain reaction were positive in 49.5% (46/93) and 24.8% (23/93) of cases, respectively. Patients with multiple mononeuropathy had a higher frequency of histopathological abnormalities (p=0.0077).

CONCLUSIONS

This study reinforces peripheral nerve biopsy's role as an important tool in the investigation of primary neural cases, contributing to the early diagnosis and also reducing diagnostic errors and the need for empirical treatment.

Leprosy surveillance study in a highly endemic Brazilian area using leprosy specific serologic tests and IFNγ whole blood assay

This surveillance study evaluated leprosy-serologic tests and the IFNγ whole-blood-assay/WBA as adjunct diagnostic tools. Previously diagnosed leprosy index cases, intradomiciliary, peridomiciliary contacts from a Brazilian endemic area were enrolled during domiciliary visits. Physical evaluation was performed by trained nurses and leprosy diagnosis confirmed by expert dermatologist. ELISA detected IgM anti-PGL-I, IgG anti-LID-1, and IgM/IgG anti-ND-O-LID antibodies. Heparinized WBA plasma stimulated with LID-1, 46f + LID-1, ML0276 + LID-1 (24 h, 37 °C, 5% CO₂₎ was tested for human IFNγ (QuantiFERON®-TB Gold/QFT-G; Qiagen). The survey included 1731 participants: 44 leprosy index cases, 64 intradomiciliary, 1623 peridomiciliary contacts. Women represented 57.7%, median age was 32 years, 72.2% had BCG scar. Leprosy prevalence was higher in intradomiciliary (8.57%) versus peridomiciliary contacts (0.67%), p < 0.001. Among 23 suspects, five leprosy cases were confirmed: 4 multibacillary/MB and 1 paucibacillary/PB. Leprosy incidence was 0.30%: 1.56% in intradomiciliary versus 0.25% in peridomiciliary (p = 0.028). Seropositivity rates were 1.9% to PGL-I, 4.9% to LID-1, and 1.0% to ND-O-LID. LID-1 positivity was higher in all groups; incident cases were LID-1 seropositive. ND-O-LID positivity was higher in intra- versus peridomiciliary contacts (p = 0.022). IFNγ WBA (40 index cases, 19 suspects, 35 intradomiciliary, 74 peridomiciliary contacts) showed higher LID-1/WBA positivity in peridomiciliary contacts (p > 0.05); significant differences among groups were seen with 46f + LID-1 but 0276 + LID-1 induced higher IFNγ levels. Incident cases were LID-1 seropositive, while IFNγ-WBA had marginal diagnostic application. As seropositivity indicates exposed individuals at higher risk of disease development, the utility of serologic screening for surveillance and prophylactic measures remains to be demonstrated.

Genomic Characterization of Mycobacterium leprae to Explore Transmission Patterns Identifies New Subtype in Bangladesh

Mycobacterium leprae, the causative agent of leprosy, is an unculturable bacterium with a considerably reduced genome (3.27 Mb) compared to homologues mycobacteria from the same ancestry. In 2001, the genome of M. leprae was first described and subsequently four genotypes (1-4) and 16 subtypes (A-P) were identified providing means to study global transmission patterns for leprosy. In order to understand the role of asymptomatic carriers we investigated M. leprae carriage as well as infection in leprosy patients (n = 60) and healthy household contacts (HHC; n = 250) from Bangladesh using molecular detection of the bacterial element RLEP in nasal swabs (NS) and slit skin smears (SSS). In parallel, to study M. leprae genotype distribution in Bangladesh we explored strain diversity by whole genome sequencing (WGS) and Sanger sequencing. In the studied cohort in Bangladesh, M. leprae DNA was detected in 33.3% of NS and 22.2% of SSS of patients with bacillary index of 0 whilst in HHC 18.0% of NS and 12.3% of SSS were positive. The majority of the M. leprae strains detected in this study belonged to genotype 1D (55%), followed by 1A (31%). Importantly, WGS allowed the identification of a new M. leprae genotype, designated 1B-Bangladesh (14%), which clustered separately between the 1A and 1B strains. Moreover, we established that the genotype previously designated 1C, is not an independent subtype but clusters within the 1D genotype. Intraindividual differences were present between the M. leprae strains obtained including mutations in hypermutated genes, suggesting mixed colonization/infection or in-host evolution. In summary, we observed that M. leprae is present in asymptomatic contacts of leprosy patients fueling the concept that these individuals contribute to the current intensity of transmission. Our data therefore emphasize the importance of sensitive and specific tools allowing post-exposure prophylaxis targeted at M. leprae-infected or -colonized individuals.

Quantitative PCR for leprosy diagnosis and monitoring in household contacts: A follow-up study, 2011-2018

Household contacts (HHC) of leprosy patients exhibit high-risk of developing leprosy and contact tracing is helpful for early diagnosis. From 2011 to 2018,2,437 HHC were examined in a clinic in Rio de Janeiro, Brazil and 16S qPCR was used for diagnosis and monitoring of contacts. Fifty-four HHCs were clinically diagnosed with leprosy at intake. Another 25 exhibited leprosy-like skin lesions at intake, 8 of which were confirmed as having leprosy (50% of which were qPCR positive) and 17 of which were diagnosed with other skin diseases (6% qPCR positive). In skin biopsies, qPCR presented a sensitivity of 0.50 and specificity of 0.94. Furthermore, 955 healthy HHCs were followed-up for at least 3 years and skin scrapings were collected from earlobes for qPCR detection. Positive qPCR indicated a non-significant relative risk of 2.52 of developing the disease. During follow-up, those who progressed towards leprosy exhibited 20% qPCR positivity, compared to 9% of those who remained healthy. Disease-free survival rates indicated that age had a significant impact on disease progression, where patients over 60 had a greater chance of developing leprosy [HR = 32.4 (3.6-290.3)]. Contact tracing combined with qPCR may assist in early diagnosis and age is a risk factor for leprosy progression.

Evaluation of the cutaneous sensation of the face in patients with different clinical forms of leprosy

Background

Leprosy can be considered to be the most common peripheral neuropathy of infectious etiology and constitutes a public health problem. The standard routine examination for assessing sensory impairment in leprosy neuropathy basically evaluates hands, feet and eyes. However, evaluation of facial cutaneous sensation is not routinely performed.

Objectives

The aim of this study was to evaluate facial cutaneous sensation in patients with different clinical forms of leprosy and compare the findings with those from healthy individuals.

Methodology

19 healthy controls and 71 leprosy patients who were being treated at a national reference center for leprosy in Brazil underwent facial sensation assessment using the Semmes-Weinstein monofilament test. This test was applied over the facial areas corresponding to the ophthalmic, maxillary and mandibular distal branches of the trigeminal nerve.

Results

The predominant clinical form in terms of changes to facial cutaneous sensation was lepromatous leprosy (LL), followed by the borderline-borderline (BB), and borderline-lepromatous (BL) forms, in comparison with healthy individuals. The distal branches most affected were the zygomatic (28.2%; 20/71), buccal (23.9%; 17/71) and nasal (22.5%; 16/71). There was asymmetrical sensory impairment of the face in 62.5% (20/32) of the cases.

Conclusion

The face is just as impaired in leprosy as are the feet, hands and eyes, but facial impairment is underdiagnosed. Our evaluation on the different sensory branches and evidence of asymmetrical impairment of the face confirm the classically described pattern of leprosy neuropathy, i.e. consisting of asymmetrical and predominantly sensory peripheral neuropathy.

Fingerstick test quantifying humoral and cellular biomarkers indicative for M. leprae infection

OBJECTIVES

New user-friendly diagnostic tests for detection of individuals infected by Mycobacterium leprae (M. leprae), the causative pathogen of leprosy, can help guide therapeutic and prophylactic treatment, thus positively contributing to clinical outcome and reduction of transmission. To facilitate point-of-care testing without the presence of phlebotomists, the use of fingerstick blood (FSB) rather than whole blood-derived serum is preferred. This study is a first proof-of-principle validating that previously described rapid serum tests detecting antibodies and cytokines can also be used with FSB.

METHODS

Quantitative detection of previously identified biomarkers for leprosy and M. leprae infection, anti-M. leprae PGL-I IgM antibodies (αPGL-I), IP-10 and CRP, was performed with lateral flow (LF) strips utilizing luminescent up-converting reporter particles (UCP) and a portable reader generating unbiased read-outs. Precise amounts of FSB samples were collected using disposable heparinized capillaries. Biomarker levels in paired FSB and serum samples were determined using UCP-LF test strips for leprosy patients and controls in Bangladesh, Brazil, South-Africa and the Netherlands.

RESULTS

Correlations between serum and FSB from the same individuals for αPGL-I, CRP and IP-10 were highly significant (p < .0001) even after FSB samples had been frozen. The αPGL-I FSB test was able to correctly identify all multibacillary leprosy patients presenting a good quantitative correlation with the bacterial index.

CONCLUSIONS

Reader-assisted, quantitative UCP-LF tests for the detection of humoral and cellular biomarkers for M. leprae infection, are compatible with FSB. This allows near-patient testing for M. leprae infection and immunomonitoring of treatment without highly trained staff. On site availability of test-result concedes immediate initiation of appropriate counselling and treatment. Alternatively, the UCP-LF format allows frozen storage of FSB samples compatible with deferred testing in central laboratories.