Leprosy: clinical and immunopathological characteristics

Multiple Papules and Nodules Over the Body with Diffuse Thickening of the Facial Skin: A Quiz

Abstract is missing (Quiz)

Serodiagnosis of paucibacillary and multibacillary leprosy using a recombinant chimeric protein composed of specific B-cell epitopes derived from Mycobacterium leprae proteins

Leprosy diagnosis is difficult due to the clinical similarity with other infectious diseases, and laboratory tests presents problems related to sensitivity and/or specificity. In this study, we used bioinformatics to assess Mycobacterium leprae proteins and formulated a chimeric protein that was tested as a diagnostic marker for the disease. The amino acid sequences from ML0008, ML0126, ML0308, ML1057, ML2028, ML2038, ML2498 proteins were evaluated, and the B-cell epitopes QASVAYPATSYADFRAHNHWWNGP, SLQRSISPNSYNTARVDP and QLLGQTADVAGAAKSGPVQPMGDRGSVSPVGQ were considered M. leprae-specific and used to construct the gene encoding the recombinant antigen. The gene was constructed, the recombinant protein was expressed, purified and tested in ELISA using 252 sera, which contained samples from multibacillary (MB) or paucibacillary (PB) leprosy patients, from their household contacts and healthy individuals, as well as from patients with Chagas disease, visceral and tegumentary leishmaniases (VL/TL), malaria, tuberculosis, and HIV. Sensitivity (Se) and specificity (Sp) for MB and PB samples compared to sera from both healthy subjects and individuals with cross-reactive diseases were 100%. The Se value for MB and PB samples compared to sera from household contacts was 100%, but Sp was 64%. In conclusion, data suggest that this protein could be considered in future studies for leprosy diagnosis.

Temporal trends and space-time distribution of leprosy relapse in Brazil from 2001 to 2021

BACKGROUND

To analyse the temporal trends and spatiotemporal distribution of leprosy relapse in Brazil from 2001 to 2021.

METHODS

An ecological study with a temporal trend approach and space-time analysis of leprosy relapse in Brazil was carried out with data from the Notifiable Diseases Information System.

RESULTS

A total of 31 334 patients who experienced leprosy relapse were identified. The number of recurrent cases tended to increase throughout the study period, and this increase was significant among females and in almost all age groups, except for those <15, 50-59 and ≥70 y. Several clusters of high- and low-risk patients were identified across all regions with a heterogeneous distribution.

CONCLUSIONS

The burden of relapse showed an increasing trend in some groups and was distributed in all regions.

Prevalence of oral manifestations of leprosy: a systematic review and meta-analysis

OBJECTIVE

To evaluate the prevalence of oral manifestations of leprosy.

STUDY DESIGN

This systematic review with meta-analysis was reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and included cross-sectional studies by 2 independent reviewers in 2 phases, who reported bacilloscopic-confirmed oral manifestations of leprosy. Studies were selected based on predetermined eligibility criteria. Searches in 6 main databases were performed, such as PubMed/MEDLINE, Embase, Scopus, Web of Science, LILACS/BVS, and LIVIVO, in addition to the gray literature. The risk of bias was assessed using the JBI Checklist for Analytical Cross-Sectional Studies, and the quantitative synthesis of the data was performed using the Jamovi 2.3 application.

RESULTS

Ten studies were included, and the meta-analysis was performed with 917 patients with different types of leprosy. The overall prevalence of oral alterations was 6.0% (95% IC, 0.02-0.11; I2 = 97.01%; Q = 75.56), with plaques (27.2%), infiltrations (18.1%), and macules (15.1%) being the most prevalent fundamental lesions, especially in multibacillary patients.

CONCLUSIONS

Even though there is no oral pathognomonic lesion of leprosy, this infectious disease can manifest in oral tissues in different ways, depending mainly on the leprosy type and stage of treatment.

Target product profiles: leprosy diagnostics

The World Health Organization (WHO) aims to reduce new leprosy cases by 70% by 2030, necessitating advancements in leprosy diagnostics. Here we discuss the development of two WHO's target product profiles for such diagnostics. These profiles define criteria for product use, design, performance, configuration and distribution, with a focus on accessibility and affordability. The first target product profile outlines requirements for tests to confirm diagnosis of leprosy in individuals with clinical signs and symptoms, to guide multidrug treatment initiation. The second target product profile outlines requirements for tests to detect Mycobacterium leprae or M. lepromatosis infection among asymptomatic contacts of leprosy patients, aiding prophylactic interventions and prevention. Statistical modelling was used to assess sensitivity and specificity requirements for these diagnostic tests. The paper highlights challenges in achieving high specificity, given the varying endemicity of M. leprae, and identifying target analytes with robust performance across leprosy phenotypes. We conclude that diagnostics with appropriate product design and performance characteristics are crucial for early detection and preventive intervention, advocating for the transition from leprosy management to prevention.

A Systemic Review and Meta-analysis on Natural Resistance-associated Macrophage Protein 1 (3'-Untranslated Region) and Nucleotide-binding Oligomerization Domain-2 (rs8057341) Polymorphisms and Leprosy Susceptibility in Asian and Caucasian Populations

The current meta-analysis aims to explore the potential correlation between natural resistance-associated macrophage protein 1 (NRAMP1) (3'-Untranslated region [3'-UTR]) and nucleotide-binding oligomerization domain-2 (NOD2 [rs8057341]) gene polymorphisms and their association with leprosy susceptibility in both Asian and Caucasian populations. Datas were retrieved from case control studies with NOD 2 and NRAMP 1 gene polymorphism associated with leprosy disease. Leprosy emerges as a particularly distinctive ailment among women on a global scale. The NRAMP1 (3'-UTR) and NOD2 (rs8057341) genetic variations play a crucial role in the progression of leprosy. A systematic review of relevant case-control studies was conducted across several databases, including ScienceDirect, PubMed, Google Scholar, and Embase. Utilizing MetaGenyo and Review Manager 5.4 Version, statistical analyses were carried out. Nine case-control studies totaling 3281 controls and 3062 leprosy patients are included in the research, with the objective of examining the potential association between NRAMP1 (3'-UTR) and NOD2 (rs8057341) gene polymorphisms and leprosy risk. The review methodology was registered in PROSPERO (ID520883). The findings reveal a robust association between NRAMP1 (3'-UTR) and NOD2 (rs8057341) gene polymorphisms and leprosy risk across various genetic models. Although the funnel plot analysis did not identify publication bias, bolstering these findings and elucidating potential gene-gene and gene-environment interactions require further comprehensive epidemiological research. This study identified a strong correlation between polymorphisms in the NOD2 (rs8057341) genes and susceptibility to leprosy across two genetic models. Further comprehensive epidemiological investigations are warranted to validate these findings and explore potential interactions between these genes and environmental factors.

Erythema Nodosum Leprosum Reaction Masquerading as Rheumatoid Arthritis

Erythema nodosum leprosum is a type 3 hypersensitivity reaction that often presents with transient eruptions of red papules, plaques, and nodules. A 52-year-old female presented with multiple joint pain that was being treated as rheumatoid arthritis (RA), but through clinical examination, she was found to have Hansen's disease with a type 2 reaction. Hence, the importance of a thorough clinical examination is a must for the timely and correct diagnosis of patients suffering from Hansen's disease.

Half a Century in Hiding: A Unique Case of Tuberculoid Leprosy with an Unprecedented Incubation Period

BACKGROUND Leprosy, also known as Hansen's disease, is a neglected tropical disease with low prevalence in the United States. The disease's long incubation period can cause delayed presentation, and most affected individuals have a history of travel or work in leprosy-endemic regions. The immune response to Mycobacterium leprae determines the clinical characteristics of leprosy, with tuberculoid leprosy being characterized by well-defined granulomas and involvement of peripheral nerves. The recommended treatment is a combination of dapsone and rifampin for 12 months. CASE REPORT A 78-year-old man with a history of extensive travel to Africa and Asia 50 years ago, presented with a non-tender, non-pruritic, and hypopigmented skin lesion on his left knee. Biopsy results confirmed granulomatous inflammation and the presence of Mycobacterium leprae, leading to a diagnosis of tuberculoid/paucibacillary leprosy. The patient received dapsone and rifampin treatment, which resulted in symptom improvement. CONCLUSIONS The patient's long incubation period of 50 years between exposure and symptom onset is remarkable and possibly one of the longest reported for tuberculoid leprosy. It emphasizes the importance of considering leprosy in cases with an extensive travel history and long incubation periods. Our patient's case presented contradictory staining results, suggesting potential sampling variation or a rare mixed leprosy form. Based on his clinical findings, he was diagnosed with tuberculoid leprosy. Early diagnosis and treatment are crucial to prevent irreversible nerve damage and improve patient outcomes. Healthcare providers should be vigilant in acquiring a detailed travel history to facilitate early diagnosis and appropriate management of leprosy cases.

Unveiling the therapeutic symphony of probiotics, prebiotics, and postbiotics in gut-immune harmony

The gut microbiota and immune system interaction play a crucial role in maintaining overall health. Probiotics, prebiotics, and postbiotics have emerged as promising therapeutic approaches to positively influence this complex axis and enhance health outcomes. Probiotics, as live bacteria, promote the growth of immune cells, shape immune responses, and maintain gut barrier integrity. They modify the gut microbiota by fostering beneficial bacteria while suppressing harmful ones. Additionally, probiotics interact with the immune system, increasing immune cell activity and anti-inflammatory cytokine production. Prebiotics, as indigestible fibers, selectively nourish beneficial microorganisms in the gut, enhancing gut microbial diversity and activity. This, in turn, improves gut health and boosts immune responses while controlling inflammation through its immunomodulatory properties. Postbiotics, produced during probiotic fermentation, such as short-chain fatty acids and antimicrobial peptides, positively impact gut health and modulate immune responses. Ensuring quality control and standardization will be essential for successful clinical implementation of these interventions. Overall, understanding and harnessing the gut microbiota-immune system interplay offer promising avenues for improving digestive and immunological health.

Leprosy reactions: Unraveling immunological mechanisms underlying tissue damage in leprosy patients

Leprosy is a chronic granulomatous infectious and disabling disease caused by two mycobacteria, Mycobacterium leprae and Mycobacterium lepromatosis. Acute inflammatory responses, known as leprosy reactions, are significant contributors to disabilities. Three types of leprosy reactions have been identified based on excessive cytokine release (e.g. type 1) or the accumulation of immune complexes in tissues inducing multiorgan damage (e.g. types 2 and 3). The type of leprosy reaction has implications on treatment and management strategies, yet are not well understood by health workers caring for leprosy patients. We attempt to describe the immunologic mechanisms behind the different leprosy reactions and the rationale for tailoring clinical treatment and management to the particular type of leprosy reaction based on the underlying immunologic situation.

Cardiovascular events associated with thalidomide and prednisone in leprosy type 2 reaction

BACKGROUND

Thalidomide is the drug of choice for the treatment of type 2 leprosy reactions and is often associated with corticosteroids. The use of these drugs in multiple myeloma is associated with the risk of cardiovascular events, but there have been few studies assessing this risk in leprosy patients.

OBJECTIVE

To evaluate the occurrence of cardiovascular events in patients with multibacillary leprosy and their correlation with the use of thalidomide and prednisone.

METHODS

Analytical cross-sectional study of all patients diagnosed with multibacillary leprosy treated at the Dermatology Service between 2012 and 2022, using electronic medical records. Thromboembolic vascular events, both arterial and venous, including acute myocardial infarction, were considered. The main independent variable was the concomitant use of thalidomide and prednisone during follow-up.

RESULTS

A total of 89 patients were included, of which 19 used thalidomide and prednisone concomitantly. There were five cardiovascular events (26.3%), three of which of deep venous thrombosis. The combined use of medications was associated with the events (PR=6.46 [3.92 to 10.65]; p<0.01).

STUDY LIMITATIONS

Small number of events, single-center retrospective study.

CONCLUSION

The hypothesis of an association between cardiovascular events and the concomitant use of thalidomide and prednisone is supported, but more robust prospective studies are required for a better assessment.

Central Nervous System Tuberculosis in a Murine Model: Neurotropic Strains or a New Pathway of Infection?

Tuberculosis (TB) of the central nervous system (CNS) is a lethal and incapacitating disease. Several studies have been performed to understand the mechanism of bacterial arrival to CNS, however, it remains unclear. Although the interaction of the host, the pathogen, and the environment trigger the course of the disease, in TB the characteristics of these factors seem to be more relevant in the genesis of the clinical features of each patient. We previously tested three mycobacterial clinical isolates with distinctive genotypes obtained from the cerebrospinal fluid of patients with meningeal TB and showed that these strains disseminated extensively to the brain after intratracheal inoculation and pulmonary infection in BALB/c mice. In this present study, BALB/c mice were infected through the intranasal route. One of these strains reaches the olfactory bulb at the early stage of the infection and infects the brain before the lungs, but the histological study of the nasal mucosa did not show any alteration. This observation suggests that some mycobacteria strains can arrive directly at the brain, apparently toward the olfactory nerve after infecting the nasal mucosa, and guides us to study in more detail during mycobacteria infection the nasal mucosa, the associated connective tissue, and nervous structures of the cribriform plate, which connect the nasal cavity with the olfactory bulb.

Challenges and advances in serological and molecular tests to aid leprosy diagnosis

Leprosy is a neglected chronic infectious disease caused by obligate intracellular bacilli, Mycobacterium leprae and Mycobacterium lepromatosis. Despite multidrug therapy (MDT) success, leprosy accounts for more than 200,000 new cases yearly. Leprosy diagnosis remains based on the dermato-neurologic examination, but histopathology of skin biopsy and bacilloscopy of intradermal scraping are subsidiary diagnostic tests that require expertise and laboratory infrastructure. This minireview summarizes the state of the art of serologic tests to aid leprosy diagnosis, highlighting enzyme-linked immunosorbent assay (ELISA) and point-of-care tests (POCT) biotechnologies. Also, the impact of the postgenomic era on the description of new recombinantly expressed M. leprae-specific protein antigens, such as leprosy Infectious Disease Research Institute (IDRI) diagnostic (LID)-1 is summarized. Highly specific and sensitive molecular techniques to detect M. leprae DNA as the quantitative polymerase chain reaction (qPCR) and the loop-mediated isothermal amplification (LAMP) are briefly reviewed. Serology studies using phenolic glycolipid-I (PGL-I) semi-synthetic antigens, LID-1 fusion antigen, and the single fusion complex natural disaccharide-octyl (NDO)-LID show high sensitivity in multibacillary (MB) patients. However, serology is not applicable to paucibacillary patients, as they have weak humoral response and robust cell-mediated response, requiring tests for cellular biomarkers. Unlike ELISA-based tests, leprosy-specific POCT based on semi-synthetic PGL-I antigens and NDO-LID 1 antigen is easy to perform, cheaper, equipment-free, and can contribute to early diagnosis avoiding permanent incapacities and helping to interrupt M. leprae transmission. Besides its use to help diagnosis of household contacts or at-risk populations in endemic areas, potential applications of leprosy serology include monitoring MDT efficacy, identification of recent infection, especially in young children, as surrogate markers of disease progression to orient adult chemoprophylaxis and as a predictor of type 2 leprosy reactions. Advances in molecular biology techniques have reduced the complexity and execution time of qPCR confirming its utility to help diagnosis while leprosy-specific LAMP holds promise as an adjunct test to detect M. leprae DNA.

New insights at the interface between leprosy and immune-mediated rheumatic diseases

Leprosy is an infectious and contagious disease of slow evolution, triggered by Mycobacterium leprae. Arthritis is its third most common manifestation, after cutaneous and peripheral nerve involvement. Since musculoskeletal symptoms may be the initial presentation of the disease, it is important for health professionals to recognize its rheumatic manifestations for early diagnosis and appropriate treatment, especially in endemic areas. In addition, cases of leprosy have increased globally, notably in patients undergoing treatment with TNF-α blockers and due to the increase in migration and travel of people from developing countries to developed countries. This review proposes to discuss the main scenarios of mimicry of different rheumatic diseases by leprosy, as well as the role of immunosuppressive drugs used in rheumatology practice in the treatment of reactional states and in the risk of developing the infection.

One Case of Tuberculosis-Like Leprosy with a Type I Leprosy Reaction

Leprosy is a chronic infectious disease primarily affecting the skin and peripheral nerves and is caused by Mycobacterium leprae. Although effective control measures have significantly reduced its global incidence in recent years, its insidious onset and diverse skin manifestations pose considerable challenges to early diagnosis, particularly among young medical practitioners. This study reports a case of tuberculoid leprosy accompanied by a type I reaction (T1R) to leprosy, aiming to contribute to the broader understanding and management of the disease. The patient came from a leprosy-endemic region and had a family history of leprosy. They first presented with neuritis, characterised by numbness in the left upper limb, which is an early-stage symptom often overlooked. This case accentuates the importance of comprehensive examination techniques, including bacteriological and histological investigations, ultrasound and magnetic resonance imaging, to identify early nerve damage, which is critical for prompt diagnosis and intervention. According to World Health Organization data, approximately 200,000 new cases of leprosy are reported worldwide each year, with a prevalence rate of 0.2 cases per 10,000 individuals. The disease exhibits two clinical forms based on the host's immune response: tuberculoid leprosy in a well-immunised population and lepromatous leprosy in a poorly immunised host. The patient in this study demonstrated signs of tuberculoid leprosy, marked by isolated skin papules and plaques, and a T1R, a tissue-destructive, immune-driven inflammatory process. This case underscores the need for ongoing education and updated diagnostic tools to facilitate the early detection of leprosy, particularly in endemic areas. Moreover, attention must be given to the comprehensive care of patients, encompassing both physical and psychological aspects, to improve their quality of life and mitigate social discrimination and prejudice.

Leprosy Reactions: Experience in the Puerto Rico Hansen's Disease Population

OBJECTIVE

Hansen's disease (HD) is a chronic granulomatous infection endemic in the tropics. Its main clinical manifestations involve the cutaneous, nervous, and musculoskeletal systems. Leprosy reactions (LR) are systemic inflammatory and immune-mediated complications of HD. These include reversal reactions (RR), erythema nodosum leprosum (ENL), and Lucio phenomenon. These reactions significantly increase disease-related morbidity and disability. We aimed to determine the number and type of LR, their association to hosts' immune responses (Ridley Jopling classification), timing of development, and treatment of HD patients in Puerto Rico.

METHODS

A retrospective medical record review was performed on 291 HD patients containing LR status data available from the Dermatology Service at the Hispanic Alliance for Clinical & Translational Research.

RESULTS

Our data revealed that 83 (29%) patients developed LR, of which 31% had RR and 69% had ENL. Most LR were observed in patients in the lepromatous border (97%): Borderline lepromatous leprosy (BL) and Lepromatous Leprosy (LL). Most patients with RR and ENL had a single episode (83% and 62%, respectively), and those that received multi-drug therapy (MDT) had a reaction onset occurring most frequently within the first year of MDT and after the first year of MDT, respectively. Prednisone was the first line treatment used to manage both types of LR.

CONCLUSION

Most lepromatous reactions occur within the lepromatous border. ENL was the most common LR. Prompt recognition and management of these immunologic reactions is essential to prevent long term nerve function impairment.

Bacterial, fungal and parasitic co-infections in leprosy: A scoping review

BACKGROUND

In leprosy patients, the most commonly reported non-viral co-infections are Tuberculosis, Leishmaniasis, Chromoblastomycosis and Helminths. The presence of a secondary infection is believed to increase the likelihood of leprosy reactions. The purpose of this review was to describe the clinical and epidemiological characteristics of the most reported bacterial, fungal, and parasitic co-infections in leprosy.

METHODOLOGY/PRINCIPAL FINDINGS

Following the PRISMA Extension for Scoping Reviews guidelines, a systematic literature search was conducted by two independent reviewers, resulting in the inclusion of 89 studies. For tuberculosis, a total of 211 cases were identified, with a median age of 36 years and male predominance (82%). Leprosy was the initial infection in 89% of cases, 82% of individuals had multibacillary disease, and 17% developed leprosy reactions. For leishmaniasis, 464 cases were identified, with a median age of 44 years and male predominance (83%). Leprosy was the initial infection in 44% of cases, 76% of individuals presented with multibacillary disease, and 18% developed leprosy reactions. Regarding chromoblastomycosis, we identified 19 cases with a median age of 54 years and male predominance (88%). Leprosy was the primary infection in 66% of cases, 70% of individuals had multibacillary disease, and 35% developed leprosy reactions. Additionally, we found 151 cases of co-infection with leprosy and helminths, with a median age of 43 years and male predominance (68%). Leprosy was the primary infection in 66% of cases, and 76% of individuals presented with multibacillary disease, while the occurrence of leprosy reactions varied from 37% to 81% across studies.

CONCLUSION

We observed a male-dominated pattern of co-infections among working-age individuals with multibacillary leprosy. Unlike prior studies reporting increased leprosy reactions in chronic viral co-infections, our findings did not indicate any increase among bacterial, fungal, or parasitic co-infections. Rather, co-infections with tuberculosis and leishmaniasis appeared to reduce leprosy reactions.

Viral co-infections in leprosy: a scoping review

CONTEXT

The most reported viral co-infections in leprosy are human immunodeficiency virus (HIV), human T-cell lymphotropic virus (HTLV), hepatitis B virus (HBV), hepatitis C virus (HCV), and SARS-CoV-2. In co-infections, the burden of an agent can be increased or decreased by the presence of others. To address this issue, we need to fully understand their prevalence, risk factors, immunology, clinical manifestations, and treatment. The purpose of this scoping review is to describe the clinical and epidemiological characteristics of the most reported viral co-infections in leprosy to inform clinicians and guide future research.

METHODS

The authors conducted a literature search of five databases for articles on each of the aforementioned co-infections published prior to October 2022. Two independent reviewers conducted the selection process and identified 53 papers meeting the study inclusion criteria. The data extraction process and evidence synthesis were conducted by one reviewer and double-checked by a second one, consistent with best practice recommendations for scoping reviews.

RESULTS

For all assessed viruses, most studies reported prevalence rates in leprosy patients higher than the general population. Studies found that HTLV, HBV, and HCV chronic infections were highest in multibacillary leprosy, whereas HIV was mostly found in paucibacillary leprosy, and SARS-Cov-2 affected leprosy subtypes equally. Overall, co-infections were also associated with higher rates of leprosy reactions, except for COVID-19. Forty-six percent of the studies discussed issues related to treatment, which led to favorable outcomes for the most part.

CONCLUSIONS

This review summarizes the existing literature on viral co-infections in leprosy patients, generating valuable insights and recommending areas for future research.

Role of gut microbiota in infectious and inflammatory diseases

Thousands of microorganisms compose the human gut microbiota, fighting pathogens in infectious diseases and inhibiting or inducing inflammation in different immunological contexts. The gut microbiome is a dynamic and complex ecosystem that helps in the proliferation, growth, and differentiation of epithelial and immune cells to maintain intestinal homeostasis. Disorders that cause alteration of this microbiota lead to an imbalance in the host’s immune regulation. Growing evidence supports that the gut microbial community is associated with the development and progression of different infectious and inflammatory diseases. Therefore, understanding the interaction between intestinal microbiota and the modulation of the host’s immune system is fundamental to understanding the mechanisms involved in different pathologies, as well as for the search of new treatments. Here we review the main gut bacteria capable of impacting the immune response in different pathologies and we discuss the mechanisms by which this interaction between the immune system and the microbiota can alter disease outcomes.

Clinical and radiological evaluation of maxillofacial and otorhinolaryngological manifestations of Hansen's disease

To characterize maxillofacial, otorhinolaryngological and oral manifestations of Hansen's disease (HD), we conducted a cross-sectional study in 21 current patients attending the Unidade Básica de Saúde de Jardim América, Espírito Santo, Brazil and 16 former patients resident at Pedro Fontes Hospital using data from computed tomography imaging, rhinoscopy, and oroscopy. Maxillofacial characteristics were compared with 37 controls. Differences in bone alterations across the three groups were determined mainly by severe resorption/atrophy being more frequent in former HD patients, with severe resorption/atrophy of the anterior alveolar process of maxilla in 50.0% (8/16) of former patients, 28.6% (6/21) of current patients and 10.8% (4/37) of controls and of nasal bones and aperture in 31.3% (5/16) of former patients compared with 0/21 current patients and two controls. There were no substantial differences in otorhinolaryngological and oroscopic findings between the two patient groups. HD patients had more tooth loss than the age-matched control group. Maxillofacial, otorhinolaryngological and oroscopic finding scores were strongly correlated only in current HD patients. Correlation between otorhinolaryngological and maxillofacial scores suggests that protocols for HD patient assessment and follow-up could include otorhinolaryngological evaluation, with radiological imaging where necessary, subject to replication of our findings in a larger study.

Bacilloscopy and polymerase chain reaction of slit-skin smears and anti-phenolic glycolipid-I serology for Hansen’s disease diagnosis

The bacilloscopy of the slit-skin smear (SSS) is the exclusive laboratory test associated with dermato-neurological evaluation for Hansen’s disease (HD) diagnosis; however, it is negative in the majority of PB or primary neural forms. Thus, a PCR technique involving different sequences and target genes has been performed with an aim to increase the sensitivity and specificity of M. leprae identification, especially in patients with low bacillary loads. Additionally, serological assays based on antibody response reflect infection levels and indicate that this could be a simpler, less invasive technique for estimating M. leprae exposure. Serological tests and PCR have been shown to be more sensitive and accurate than the SSS. Our study aimed to measure accuracy and performance among the SSS and PCR of dermal scrapings stored on filter paper and APGL-I serology for diagnosis in HD. A cross-sectional study analyzing the medical records (n = 345) of an HD outpatient-dermatology clinic from 2014 to 2021 was conducted. Accuracy performance parameters, correlation, and concordance were used to assess the value among the SSS, PCR, and APGL-I exams in HD. The SSS presented 24.5% sensitivity, 100% specificity, 37.4% accuracy, and the lowest negative predictive value (21.5%). The PCR assay had 41, 100, and 51% sensitivity, specificity, and accuracy, respectively. PCR and APGL-I serology increased the detection of HD cases by 16 and 20.6%, respectively. PCR was positive in 51.3% of patients when the SSS was negative. The SSS obtained moderate concordance with PCR [k-value: 0.43 (CI: 0.33–0.55)] and APGL-I [k-value: 0.41 (CI: 0.31–0.53)]. A moderate positive correlation was found between the APGL-I index and the bacillary index (r = 0.53; P < 0.0001). Thus, the use of the SSS is a low sensitivity and accuracy method due to its low performance in HD detection. The use of PCR and serological tests allows for a more sensitive and accurate diagnosis of patients.