New findings in the pathogenesis of leprosy and implications for the management of leprosy

The Neurological Impact of Leprosy: Manifestations and Treatment Approaches

BACKGROUND AND OBJECTIVES

Leprosy primarily affects peripheral nerves, leading to significant neurological complications such as polyneuritis, mononeurosis, and autonomic dysfunction, which contribute to severe disabilities and impaired quality of life for patients. This scoping review aims to investigate the neurological manifestations and main treatments of leprosy patients.

MATERIALS AND METHODS

Studies were identified from an online search of PubMed, Web of Science, Cochrane Library, Embase, and Scopus databases. This review has been registered on OSF (n) PQBYH.

RESULTS

Neurological complications of leprosy, such as neuropathy and paralysis, necessitate accurate diagnosis and treatment, as immunological reactions can exacerbate nerve damage. Various studies highlight the effectiveness of personalized therapies, such as corticosteroids, multi-drug therapy (MDT), and surgical interventions, in improving symptoms and neurological function in leprosy patients.

CONCLUSIONS

Managing neurological complications of leprosy necessitates careful diagnosis and treatment, as many patients experience unresolved peripheral neuropathy despite multidrug therapy. Future research should focus on improving diagnostic tools, exploring the link between neuropathic pain and psychological issues, and developing effective vaccines and treatments to enhance patient outcomes.

The spectrum of central nervous system manifestations in leprosy: a systematic review of published case reports and case series

BACKGROUND

This systematic review aimed to investigate central nervous system (CNS) involvement in leprosy by analysing multiple cohort studies, individual cases and case series.

METHODS

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed. PubMed, Scopus and Embase databases were searched up to 8 July 2023, using a predefined search strategy. Inclusion criteria included patients diagnosed with leprosy with evidence of CNS involvement. The quality of the included cases was evaluated using the Joanna Briggs Institute checklist.

RESULTS

A total of 34 records were identified, including 18 cohort studies and 16 reports describing 27 isolated cases. Autopsies revealed macroscopic changes in the spinal cord, neurofibrillary tangles and senile plaques. Mycobacterium leprae was detected in neurons of the medulla oblongata and spinal cord using PCR and phenolic glycolipid 1 staining. Cerebrospinal fluid (CSF) analysis showed inflammatory changes, increased gamma globulins and detection of Mycobacterium leprae antigens and antibodies. In 21 patients (78%), spinal cord/brachial plexus abnormities were detected. In the majority, MRI revealed T2/fluid-attenuated inversion recovery (FLAIR) hyperintensity in the cervical cord. In patients with brainstem involvement, T2/FLAIR hyperintensity was noted in the cerebellar peduncles, facial nerve nuclei and/or other cranial nerve nuclei. Brain parenchymal involvement was noted in three patients.

CONCLUSIONS

This systematic review provides evidence of CNS involvement in leprosy, based on autopsy findings, neuroimaging, CSF analysis and neurophysiological studies.

ncRNAs: an unexplored cellular defense mechanism in leprosy

Leprosy is an infectious disease primarily caused by the obligate intracellular parasite Mycobacterium leprae. Although it has been considered eradicated in many countries, leprosy continues to be a health issue in developing nations. Besides the social stigma associated with it, individuals affected by leprosy may experience nerve damage leading to physical disabilities if the disease is not properly treated or early diagnosed. Leprosy is recognized as a complex disease wherein socioenvironmental factors, immune response, and host genetics interact to contribute to its development. Recently, a new field of study called epigenetics has emerged, revealing that the immune response and other mechanisms related to infectious diseases can be influenced by noncoding RNAs. This review aims to summarize the significant advancements concerning non-coding RNAs in leprosy, discussing the key perspectives on this novel approach to comprehending the pathophysiology of the disease and identifying molecular markers. In our view, investigations on non-coding RNAs in leprosy hold promise and warrant increased attention from researches in this field.

The impact of single-cell genomics on the field of mycobacterial infection

Genome sequencing projects of humans and other organisms reinforced that the complexity of biological systems is largely attributed to the tight regulation of gene expression at the epigenome and RNA levels. As a consequence, plenty of technological developments arose to increase the sequencing resolution to the cell dimension creating the single-cell genomics research field. Single-cell RNA sequencing (scRNA-seq) is leading the advances in this topic and comprises a vast array of different methodologies. scRNA-seq and its variants are more and more used in life science and biomedical research since they provide unbiased transcriptomic sequencing of large populations of individual cells. These methods go beyond the previous “bulk” methodologies and sculpt the biological understanding of cellular heterogeneity and dynamic transcriptomic states of cellular populations in immunology, oncology, and developmental biology fields. Despite the large burden caused by mycobacterial infections, advances in this field obtained via single-cell genomics had been comparatively modest. Nonetheless, seminal research publications using single-cell transcriptomics to study host cells infected by mycobacteria have become recently available. Here, we review these works summarizing the most impactful findings and emphasizing the different and recent single-cell methodologies used, potential issues, and problems. In addition, we aim at providing insights into current research gaps and potential future developments related to the use of single-cell genomics to study mycobacterial infection.

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. Thus, there is still a need to develop newer antileprosy molecules either of natural or semi-synthetic origin.

OBJECTIVES

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.

Detection of Mycobacterium leprae DNA in clinical and environmental samples using serological analysis and PCR

BACKGROUND

Leprosy is a chronic infectious disease caused by Mycobacterium leprae and persists as a serious public health problem in Brazil. This microorganism is inculturable, making it difficult to diagnose and elucidate details of its transmission chain. Thus, this study aimed to analyze the dynamics of environmental transmission of M. leprae in a case-control study in the city of Mossoró, Brazil.

METHODS AND RESULTS

Data of clinical, epidemiological, bacilloscopic, and serological evaluation of 22 newly diagnosed patients were compared, with molecular results of detection of specific genome regions RLEP and 16S rRNA of M. leprae in samples of the nasal swab, saliva, and house dust of these individuals and their controls (44 household contacts and 44 peridomiciliar contacts). The rapid serological tests evaluated, ML flow (IgM ND-O-BSA) and OrangeLife® (IgM and IgG anti NDO-LID 1) showed similar results, with greater positivity among paucibacillaries by OrangeLife® (54.5%). Positivity for nasal swab and saliva in multibacillary patients with RLEP primer was 16.7% and 33.3%, respectively. There was no detection of bacterial DNA in house dust or among paucibacillaries. The OrangeLife® test indicated that the lower the amount of windows, the more transmission in the house (3.79 more chances). Having a history of leprosy cases in the family increased the risk by 2.89 times, and being over 60 years of age gave 3.6 times more chances of acquiring the disease. PCR positivity was higher among all clinical samples using the M. leprae RLEP region than 16S rRNA.

CONCLUSIONS

In this study, the serological and PCR analysis were capable of detecting M. leprae DNA in clinical samples but not in the environmental samples. Close monitoring of patients and household contacts appears an effective measure to reduce the transmission of leprosy in endemic areas.

Detection of anti-M. leprae antibodies in children in leprosy-endemic areas: A systematic review

BACKGROUND

Leprosy elimination primarily targets transmission of Mycobacterium leprae which is not restricted to patients' households. As interruption of transmission is imminent in many countries, a test to detect infected asymptomatic individuals who can perpetuate transmission is required. Antibodies directed against M. leprae antigens are indicative of M. leprae infection but cannot discriminate between active and past infection. Seroprevalence in young children, however, reflects recent M. leprae infection and may thus be used to monitor transmission in an area. Therefore, this literature review aimed to evaluate what has been reported on serological tests measuring anti-M. leprae antibodies in children without leprosy below the age of 15 in leprosy-endemic areas.

METHODS AND FINDINGS

A literature search was performed in the databases Pubmed, Infolep, Web of Science and The Virtual Health Library. From the 724 articles identified through the search criteria, 28 full-text articles fulfilled all inclusion criteria. Two additional papers were identified through snowballing, resulting in a total of 30 articles reporting data from ten countries. All serological tests measured antibodies against phenolic glycolipid-I or synthetic derivatives thereof, either quantitatively (ELISA or UCP-LFA) or qualitatively (ML-flow or NDO-LID rapid test). The median seroprevalence in children in endemic areas was 14.9% and was stable over time if disease incidence remained unchanged. Importantly, seroprevalence decreased with age, indicating that children are a suitable group for sensitive assessment of recent M. leprae infection. However, direct comparison between areas, solely based on the data reported in these studies, was impeded by the use of different tests and variable cut-off levels.

CONCLUSIONS

Quantitative anti-PGL-I serology in young children holds promise as a screening test to assess M. leprae infection and may be applied as a proxy for transmission and thereby as a means to monitor the effect of (prophylactic) interventions on the route to leprosy elimination.

Potential Role of CXCL10 in Monitoring Response to Treatment in Leprosy Patients

The treatment of multibacillary cases of leprosy with multidrug therapy (MDT) comprises 12 doses of a combination of rifampicin, dapsone and clofazimine. Previous studies have described the immunological phenotypic pattern in skin lesions in multibacillary patients. Here, we evaluated the effect of MDT on skin cell phenotype and on the Mycobacterium leprae-specific immune response. An analysis of skin cell phenotype demonstrated a significant decrease in MRS1 (SR-A), CXCL10 (IP-10) and IFNG (IFN-γ) gene and protein expression after MDT release. Patients were randomized according to whether they experienced a reduction in bacillary load after MDT. A reduction in CXCL10 (IP-10) in sera was associated with the absence of a reduction in the bacillary load at release. Although IFN-γ production in response to M. leprae was not affected by MDT, CXCL10 (IP-10) levels in response to M. leprae increased in cells from patients who experienced a reduction in bacillary load after treatment. Together, our results suggest that CXCL10 (IP-10) may be a good marker for monitoring treatment efficacy in multibacillary patients.

Strategies for drug target identification in Mycobacterium leprae

Hansen's disease (HD), or leprosy, continues to be endemic in many parts of the world. Although multidrug therapy (MDT) is successful in curing a large number of patients, some of them abandon it because it is a long-term treatment. Therefore, identification of new drug targets in Mycobacterium leprae is considered of high importance. Here, we introduce an overview of in silico and in vitro studies that might be of help in this endeavor. The essentiality of M. leprae proteins is reviewed with discussion of flux balance analysis, gene expression, and knockout articles. Finally, druggability techniques are proposed for the validation of new M. leprae protein targets (see Fig. 1).

Pathogenesis and Host Immune Response in Leprosy

Leprosy is an ancient insidious disease caused by Mycobacterium leprae, where the skin and peripheral nerves undergo chronic granulomatous infections, leading to sensory and motor impairment with characteristic deformities. Susceptibility to leprosy and its disease state are determined by the manifestation of innate immune resistance mediated by cells of monocyte lineage. Due to insufficient innate resistance, granulomatous infection is established, influencing the specific cellular immunity. The clinical presentation of leprosy ranges between two stable polar forms (tuberculoid to lepromatous) and three unstable borderline forms. The tuberculoid form involves Th1 response, characterized by a well demarcated granuloma, infiltrated by CD4⁺ T lymphocytes, containing epitheloid and multinucleated giant cells. In the lepromatous leprosy, there is no characteristic granuloma but only unstructured accumulation of ineffective macrophages containing engulfed pathogens. Th1 response, characterised by IFN-γ and IL-2 production, activates macrophages in order to kill intracellular pathogens. Conversely, a Th2 response, characterized by the production of IL-4, IL-5 and IL-10, helps in antibody production and consequently downregulates the cell-mediated immunity induced by the Th1 response. M. lepare has a long generation time and its inability to grow in culture under laboratory conditions makes its study challenging. The nine-banded armadillo still remains the best clinical and immunological model to study host-pathogen interaction in leprosy. In this chapter, we present cellular morphology and the genomic uniqueness of M. leprae, and how the pathogen shows tropism for Schwann cells, macrophages and dendritic cells.

Poor WASH (Water, Sanitation, and Hygiene) Conditions Are Associated with Leprosy in North Gondar, Ethiopia

Access to safe water, sanitation, and hygiene (WASH) is critical for preventing the spread of neglected tropical diseases (NTDs) including leprosy. WASH-related transmission factors remain largely unexplored in the leprosy transmission cycle. The aim of this project is to better understand WASH exposures among leprosy cases through a case-control study in North Gondar, Ethiopia. We hypothesized that leprosy cases were more likely to have inadequate WASH access and were more likely to have concurrent schistosomiasis, as schistosomiasis immune consequences may facilitate leprosy infection. Forty leprosy cases (forty-one controls) were enrolled, tested for Schistosomamansoni, administered a demographic and WASH survey, and assigned a WASH index score. WASH factors significantly associated with leprosy on adjusted analyses included open defecation (aOR = 19.9, 95% CI 2.2, 176.3) and lack of access to soap (aOR = 7.3, 95% CI 1.1, 49.9). S. mansoni was detected in 26% of participants and in stratified analysis those with leprosy had a 3.6 (95% CI (0.8, 15.9)) greater odds of schistosomiasis in districts bordering the lake, compared to 0.33 lower odds of schistosomiasis in districts not bordering the lake (95% CI (0.09, 1.2)). Overall, results suggest that leprosy transmission may be related to WASH adequacy and access as well as to schistosomiasis co-infection.

[Mortality from leprosy in highly endemic contexts: integrated temporal-spatial analysis in BrazilMortalidad por lepra en zonas de alta endemicidad: análisis espacio-temporal integrado en Brasil]

Objetivo.

Descrever as tendências temporais e os padrões espaciais da mortalidade relacionada à hanseníase nas regiões Norte e Nordeste do Brasil de 2001 a 2017.

Métodos.

Estudo ecológico misto de base populacional, de tendência temporal e espacial, baseado em dados secundários de declarações de óbito (DO) do Sistema de Informação de Mortalidade do Ministério da Saúde (SIM). As DO foram examinadas para extração dos registros de hanseníase como causa básica e associada de morte.

Resultados.

Foram registrados 4 907 óbitos relacionados à hanseníase no período de interesse, 59,3% como causa associada. A hanseníase não especificada (A30.9) foi a causa mais citada nas declarações de óbito (causa básica: 72,7%; causa associada: 76,1%). Verificou-se risco acrescido de mortalidade por hanseníase em pessoas do sexo masculino, com idade ≥60 anos e de raça/cor preta ou parda. A tendência temporal por análise de pontos de inflexão (joinpoints) apresentou incremento na tendência geral da mortalidade na região Nordeste e nos estados de Tocantins, Maranhão, Alagoas e Bahia, assim como no sexo masculino. Para a distribuição espacial das taxas de mortalidade ajustadas por idade e sexo, assim como para as análises das médias móveis espaciais e da razão de mortalidade padronizada, padrões acima da média da área de estudo foram identificados para Acre, Rondônia, sul do estado do Pará, Tocantins, Maranhão, Piauí, sul do Ceará e regiões do norte e sul da Bahia.

Conclusões.

A mortalidade por hanseníase nas regiões Norte e Nordeste é expressiva e persistente, com padrão focal de ocorrência em territórios e populações com maior vulnerabilidade. Ressalta-se a necessidade de fortalecer a atenção integral à hanseníase na rede de atenção do Sistema Único de Saúde dessas regiões.

Diet and nutrition: An important risk factor in leprosy

Leprosy, once considered as poor man's disease may cause severe neurological complications and physical disabilities. Classification of leprosy depends upon the cell mediated and humoral immune responses of the host, from tuberculoid to lepromatous stage. Current therapy to prevent the disease is not only very lengthy but also consists of expensive multiple antibiotics in combination. Treatment and the duration depend on the bacillary loads, from six months in paucibacillary to a year in multibacillary leprosy. Although as per WHO recommendations, these antibiotics are freely available but still out of reach to patients of many rural areas of the world. In this review, we have focused on the nutritional aspect during the multi-drug therapy of leprosy along with the role of nutrition, particularly malnutrition, on susceptibility of Mycobacterium leprae and development of clinical symptoms. We further discussed the diet plan for the patients and how diet plans can affect the immune responses during the disease.

Clinico-immunological spectrum of American tegumentary leishmaniasis and leprosy coinfection: A case series in Southeastern Brazil

INTRODUCTION

American tegumentary leishmaniasis (ATL) and leprosy share common areas of prevalence, but reports of coinfection are scarce.

METHODS

We report a series of 9 ATL-leprosy cases and discuss the association. An integrative diagram to analyze the clinico-immunological features of coinfection with both diseases.

RESULTS

Nine patients with leishmaniasis (5 cutaneous, 3 mucocutaneous, 1 disseminated case) exhibited concurrent infection with distinct clinical forms of leprosy. Our diagram-based analysis evidenced a divergent clinico-immunological spectrum for each disease in 8 out of 9 cases.

CONCLUSIONS

The spectrum of ATL-leprosy comorbidity suggests that the host has a specific immune response against each pathogen.

The lung microbiome, vitamin D, and the tuberculous granuloma: A balance triangle

Mycobacterium tuberculosis (Mtb) has the extraordinary ability to persist for decades within granulomas in the human host. These histopathological structures involved in both protection and pathogenesis, are subject to various influences from the host systemically and through micro-niche environments. Despite the fact that vitamin D (VD) has a key role in macrophage activation and mycobacterial clearance in the early stages of Mtb infection, the overall role of VD in granuloma maintenance or functionality has been scarcely studied. VD deficiency has long time been known to influence on gut microbiota composition, and recent studies have shown that it can also impact on respiratory microbiome. The human microbiota plays an important role in pathogen colonization resistance, and it has been proposed to play a potential role in TB pathogenesis. In this article, we have reviewed current knowledge on the interaction between VD, the lung microbiome and TB, and propose mechanisms by which the tuberculous granuloma's outcome could be modulated by these two factors. The determinants of the final fate of lung granulomas are still unclear, and deciphering the underlying drivers of Mtb infection outcome within those structures is of critical importance.

Cutaneous Mycobacterial Infections

Humans encounter mycobacterial species due to their ubiquity in different environmental niches. In many individuals, pathogenic mycobacterial species may breach our first-line barrier defenses of the innate immune system and modulate the activation of phagocytes to cause disease of the respiratory tract or the skin and soft tissues, sometimes resulting in disseminated infection. Cutaneous mycobacterial infections may cause a wide range of clinical manifestations, which are divided into four main disease categories: (i) cutaneous manifestations of Mycobacterium tuberculosis infection, (ii) Buruli ulcer caused by Mycobacterium ulcerans and other related slowly growing mycobacteria, (iii) leprosy caused by Mycobacterium leprae and Mycobacterium lepromatosis, and (iv) cutaneous infections caused by rapidly growing mycobacteria. Clinically, cutaneous mycobacterial infections present with widely different clinical presentations, including cellulitis, nonhealing ulcers, subacute or chronic nodular lesions, abscesses, superficial lymphadenitis, verrucous lesions, and other types of findings. Mycobacterial infections of the skin and subcutaneous tissue are associated with important stigma, deformity, and disability. Geography-based environmental exposures influence the epidemiology of cutaneous mycobacterial infections. Cutaneous tuberculosis exhibits different clinical phenotypes acquired through different routes, including via extrinsic inoculation of the tuberculous bacilli and dissemination to the skin from other sites, or represents hypersensitivity reactions to M. tuberculosis infection. In many settings, leprosy remains an important cause of neurological impairment, deformity, limb loss, and stigma. Mycobacterium lepromatosis, a mycobacterial species related to M. leprae, is linked to diffuse lepromatous leprosy of Lucio and Latapí. Mycobacterium ulcerans produces a mycolactone toxin that leads to subcutaneous tissue destruction and immunosuppression, resulting in deep ulcerations that often produce substantial disfigurement and disability. Mycobacterium marinum, a close relative of M. ulcerans, is an important cause of cutaneous sporotrichoid nodular lymphangitic lesions. Among patients with advanced immunosuppression, Mycobacterium kansasii, the Mycobacterium avium-intracellulare complex, and Mycobacterium haemophilum may cause cutaneous or disseminated disease. Rapidly growing mycobacteria, including the Mycobacterium abscessus group, Mycobacterium chelonei, and Mycobacterium fortuitum, are increasingly recognized pathogens in cutaneous infections associated particularly with plastic surgery and cosmetic procedures. Skin biopsies of cutaneous lesions to identify acid-fast staining bacilli and cultures represent the cornerstone of diagnosis. Additionally, histopathological evaluation of skin biopsy specimens may be useful in identifying leprosy, Buruli ulcer, and cutaneous tuberculosis. Molecular assays are useful in some cases. The treatment for cutaneous mycobacterial infections depends on the specific pathogen and therefore requires a careful consideration of antimicrobial choices based on official treatment guidelines.

Leprosy As a Complex Infection: Breakdown of the Th1 and Th2 Immune Paradigm in the Immunopathogenesis of the Disease

Leprosy is a chronic infectious disease whose evolution involves complex immune mechanisms of the host that influence the clinical presentation of the disease. For many years, the main interpretation of the host defense response was based on characterization of the established immune paradigm between T helper (Th) 1 and Th2 lymphocytes. However, with advances in the knowledge of immunology, new approaches have emerged along with the development of new immunological pathways that have changed the interpretation of the long-established paradigm of the polar forms of the disease, especially with the identification of new subtypes of T lymphocytes such as Th9, Th17, Th22, and Tregs. Thus, this review discusses the role of these new subtypes of T helper lymphocytes and how the development of the immune response of these cells modifies the pattern of the Th1/Th2 response in the immunopathogenesis of leprosy.

Cytokines as biomarkers to monitoring the impact of multidrug therapy in immune response of leprosy patients

Leprosy or Hansen's disease is a chronic infectious disease of the skin and nerves, caused by the intracellular bacilli Mycobacterium leprae. It is characterized by a spectrum of clinical forms depending on the host's immune response to M. leprae. Patients with tuberculoid (TT) leprosy have strong cell-mediated immunity (CMI) with elimination of the bacilli, whereas patients with lepromatous (LL) leprosy exhibit defective CMI to M. leprae. Despite advances in the understanding of the pathogenesis of leprosy and the development of new therapeutic strategies, there is a need for the identification of biomarkers which be used for early diagnosis and to discrimination between different forms of the disease, as prognostic markers. Here, we analyzed the serum levels of IL-1β, IL-6, IL-8, IL-10, IL-12p70, IL-13, IL-17A, IFN-γ and TNF in order to address the contribution of these cytokines in late phase of M. leprae infection, and the impact of multidrug therapy (MDT). Our results demonstrated that patients of LL group presented higher expression of serum levels of inflammatory cytokines before MDT, while TT patients presented a balance between inflammatory and regulatory cytokines. MDT changes the profile of serum cytokines in M. leprae infected patients, as evidenced by the cytokine network, especially in TT patients. LL patients displayed a multifaceted cytokine system characterized by strong connecting axes involving inflammatory/regulatory molecules, while TT patients showed low involvement of regulatory cytokines in network overall. Cytokines can be identified as good biomarkers of the impact of MDT on the immune system and the effectiveness of treatment.

Unsolved matters in leprosy: a descriptive review and call for further research

Leprosy, a chronic mycobacterial infection caused by Mycobacterium leprae, is an infectious disease that has ravaged human societies throughout millennia. This ancestral pathogen causes disfiguring cutaneous lesions, peripheral nerve injury, ostearticular deformity, limb loss and dysfunction, blindness and stigma. Despite ongoing efforts in interrupting leprosy transmission, large numbers of new cases are persistently identified in many endemic areas. Moreover, at the time of diagnosis, most newly identified cases have considerable neurologic disability. Many challenges remain in our understanding of the epidemiology of leprosy including: (a) the precise mode and route of transmission; (b) the socioeconomic, environmental, and behavioral factors that promote its transmission; and

Leprosy in Denmark 1980-2010: a review of 15 cases

Background

Leprosy, caused by Mycobacterium leprae, is a chronic and progressive granulomatous disease affecting mainly the skin and the peripheral nervous system. If left unrecognized, the infection can lead to permanent nerve damage and disability. The clinical presentation depends on the immune response of the patient and can result in a wide spectrum of symptoms. Leprosy is a rare encounter in Scandinavia but remains endemic in some parts of the world, with some areas reporting an increasing incidence. We performed a retrospective record review of leprosy cases in Denmark from 1980 to 2010 with the purpose of presenting the most common geographical, demographic and clinical findings and to discuss the diagnostic and therapeutic challenges of patients with leprosy.

Case presentation

In total 15 cases were reviewed. The majority (87 %) of leprosy patients in Denmark were born in South- and Southeast Asia, and were presumed to have contracted the infection in their countries of origin. Patients were predominately young males (mean age: 28.6 years). Anaesthetic skin lesion with or without nerve enlargement were the most common clinical presentations (73 %). Immunological leprosy reactions were seen in 40 % of the cases. Diagnoses were based on clinical findings and skin biopsies. Treatment length varied but all patients received multidrug regimens.

Conclusion

Leprosy should be kept in mind when encountering patients with suspicious skin lesions originating from leprosy endemic areas or with history of travel or work in the tropics. Due to the long incubation period with symptoms presenting long after immigration or return, clinicians often do not have the diagnosis in mind. The wide spectrum of symptoms and immunological reactions further complicates the diagnostic process. Treatment of leprosy and the complicated immunological reactions, which frequently accompanies the infection, should be performed in collaboration with a specialist.

Electronic supplementary material

The online version of this article (doi:10.1186/s13104-015-1768-6) contains supplementary material, which is available to authorized users.

Longitudinal immune profiles in type 1 leprosy reactions in Bangladesh, Brazil, Ethiopia and Nepal

Background

Acute inflammatory reactions are a frequently occurring, tissue destructing phenomenon in infectious- as well as autoimmune diseases, providing clinical challenges for early diagnosis. In leprosy, an infectious disease initiated by Mycobacterium leprae (M. leprae), these reactions represent the major cause of permanent neuropathy. However, laboratory tests for early diagnosis of reactional episodes which would significantly contribute to prevention of tissue damage are not yet available.

Although classical diagnostics involve a variety of tests, current research utilizes limited approaches for biomarker identification. In this study, we therefore studied leprosy as a model to identify biomarkers specific for inflammatory reactional episodes.

Methods

To identify host biomarker profiles associated with early onset of type 1 leprosy reactions, prospective cohorts including leprosy patients with and without reactions were recruited in Bangladesh, Brazil, Ethiopia and Nepal. The presence of multiple cyto-/chemokines induced by M. leprae antigen stimulation of peripheral blood mononuclear cells as well as the levels of antibodies directed against M. leprae-specific antigens in sera, were measured longitudinally in patients.

Results

At all sites, longitudinal analyses showed that IFN-γ-, IP-10-, IL-17- and VEGF-production by M. leprae (antigen)-stimulated PBMC peaked at diagnosis of type 1 reactions, compared to when reactions were absent. In contrast, IL-10 production decreased during type 1 reaction while increasing after treatment. Thus, ratios of these pro-inflammatory cytokines versus IL-10 provide useful tools for early diagnosing type 1 reactions and evaluating treatment. Of further importance for rapid diagnosis, circulating IP-10 in sera were significantly increased during type 1 reactions. On the other hand, humoral immunity, characterized by M. leprae-specific antibody detection, did not identify onset of type 1 reactions, but allowed treatment monitoring instead.

Conclusions

This study identifies immune-profiles as promising host biomarkers for detecting intra-individual changes during acute inflammation in leprosy, also providing an approach for other chronic (infectious) diseases to help early diagnose these episodes and contribute to timely treatment and prevention of tissue damage.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-015-1128-0) contains supplementary material, which is available to authorized users.

Leprosy in the 21st century

Despite significant improvements in leprosy (Hansen's disease) treatment and outlook for patients since the introduction of multidrug therapy (MDT) 3 decades ago, the global incidence remains high, and patients often have long-term complications associated with the disease. In this article, we discuss recent findings related to genetics, susceptibility, and disease reservoirs and the implications of these findings for Hansen's disease control and health outcomes for patients. We describe the continued difficulties associated with treatment of inflammatory episodes known as "leprosy reactions," which cause much of the disability associated with the disease and can affect people for many years after MDT is complete. We also discuss some of the contemporary challenges for physicians and patients, including international and internal migration of people affected by the disease. We suggest some important areas of focus for future Hansen's disease research.