Protecting people against leprosy: chemoprophylaxis and immunoprophylaxis

Profile of the leprosy endemic in the district of Murrupula, Nampula, Mozambique: A population-based study

BACKGROUND

Leprosy is a neglected chronic infection caused by Mycobacterium leprae, that is curable. The magnitude of the disease and severity of the debilitation it causes renders leprosy a public health problem. This study aimed to analyze the endemic profile of leprosy in the Murrupula district and evaluate the socioeconomic, clinical, and serological profiles of leprosy contacts.

METHODS

A cross-sectional study of patients with leprosy diagnosed between 2013 and 2017 and their household and community contacts was conducted in Murrupula District, Nampula Province, Mozambique. Interviews, simplified dermatoneurological examinations, Mycobacterium leprae flow (ML Flow) tests, and Mitsuda tests were performed.

RESULTS

Most of the leprosy cases were multibacillary. The patients had some degree of physical disability. ML Flow positivity was more common in household contacts of the patients diagnosed with leprosy and in community individuals who spontaneously presented for testing. In total, 17 patients were diagnosed with leprosy.

CONCLUSIONS

This study revealed an active chain of transmission, hidden prevalence, and operational deficiencies in leprosy surveillance and care. The results suggest that the implementation of a public health policy for leprosy prevention and control in Nampula Province is necessary. In future, the possibility of expanding the policy to the entire country should be considered.

Algorithm design for a cytokine release assay of antigen-specific in vitro stimuli of circulating leukocytes to classify leprosy patients and household contacts

Background

Immunological biomarkers have often been used as a complementary approach to support clinical diagnosis in several infectious diseases. The lack of commercially available laboratory tests for conclusive early diagnosis of leprosy has motivated the search for novel methods for accurate diagnosis. In the present study, we describe an integrated analysis of a cytokine release assay using a machine learning approach to create a decision tree algorithm. This algorithm was used to classify leprosy clinical forms and monitor household contacts.

Methods

A model of Mycobacterium leprae antigen-specific in vitro assay with subsequent cytokine measurements by enzyme-linked immunosorbent assay was employed to measure the levels of tumor necrosis factor (TNF), interferon-γ, interleukin 4, and interleukin 10 (IL-10) in culture supernatants of peripheral blood mononuclear cells from patients with leprosy, healthy controls, and household contacts. Receiver operating characteristic curve analysis was carried out to define each cytokine’s global accuracy and performance indices to identify clinical subgroups.

Results

Data demonstrated that TNF (control culture [CC]: AUC = 0.72; antigen-stimulated culture [Ml]: AUC = 0.80) and IL-10 (CC: AUC = 0.77; Ml: AUC = 0.71) were the most accurate biomarkers to classify subgroups of household contacts and patients with leprosy, respectively. Decision tree classifier algorithms for TNF analysis categorized subgroups of household contacts according to the operational classification with moderate accuracy (CC: 79% [48/61]; Ml: 84% [51/61]). Additionally, IL-10 analysis categorized leprosy patients’ subgroups with moderate accuracy (CC: 73% [22/30] and Ml: 70% [21/30]).

Conclusions

Together, our findings demonstrated that a cytokine release assay is a promising method to complement clinical diagnosis, ultimately contributing to effective control of the disease.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Predictive nomogram for leprosy using genetic and epidemiological risk factors in Southwestern China: Case-control and prospective analyses

Background

There is a high incidence of leprosy among house-contacts compared with the general population. We aimed to establish a predictive model using these genetic factors along with epidemiological factors to predict leprosy risk of leprosy household contacts (HHCs).

Methods

Weighted genetic risk score (wGRS) encompassing genome wide association studies (GWAS) variants and five non-genetic factors were examined in a case–control design associated with leprosy risk including 589 cases and 647 controls from leprosy HHCs. We constructed a risk prediction nomogram and evaluated its performance by concordance index (C-index) and calibration curve. The results were validated using bootstrap resampling with 1000 resamples and a prospective design including 1100 HHCs of leprosy patients.

Finding

The C-index for the risk model was 0·792 (95% confidence interval [CI] 0·768-0·817), and was confirmed to be 0·780 through bootstrapping validation. The calibration curve for the probability of leprosy showed good agreement between the prediction of the nomogram and actual observation. HHCs were then divided into the low-risk group (nomogram score ≤ 81) and the high-risk group (nomogram score > 81). In prospective analysis, 12 of 1100 participants had leprosy during 63 months’ follow-up. We generated the nomogram for leprosy in the validation cohort (C-index 0·773 [95%CI 0·658-0·888], sensitivity75·0%, specificity 66·8%). Interpretation The nomogram achieved an effective prediction of leprosy in HHCs. Using the model, the risk of an individual contact developing leprosy can be determined, which can lead to a rational preventive choice for tracing higher-risk leprosy contacts.

Funding

The ministry of health of China, ministry of science and technology of China, Chinese academy of medical sciences, Jiangsu provincial department of science and technology, Nanjing municipal science and technology bureau.

Geospatial epidemiology of leprosy in northwest Bangladesh: a 20-year retrospective observational study

Background

Leprosy is known to be unevenly distributed between and within countries. High risk areas or ‘hotspots’ are potential targets for preventive interventions, but the underlying epidemiologic mechanisms that enable hotspots to emerge, are not yet fully understood. In this study, we identified and characterized leprosy hotspots in Bangladesh, a country with one of the highest leprosy endemicity levels globally.

Methods

We used data from four high-endemic districts in northwest Bangladesh including 20 623 registered cases between January 2000 and April 2019 (among ~ 7 million population). Incidences per union (smallest administrative unit) were calculated using geospatial population density estimates. A geospatial Poisson model was used to detect incidence hotspots over three (overlapping) 10-year timeframes: 2000–2009, 2005–2014 and 2010–2019. Ordinal regression models were used to assess whether patient characteristics were significantly different for cases outside hotspots, as compared to cases within weak (i.e., relative risk (RR) of one to two), medium (i.e., RR of two to three), and strong (i.e., RR higher than three) hotspots.

Results

New case detection rates dropped from 44/100 000 in 2000 to 10/100 000 in 2019. Statistically significant hotspots were identified during all timeframes and were often located at areas with high population densities. The RR for leprosy was up to 12 times higher for inhabitants of hotspots than for people living outside hotspots. Within strong hotspots (1930 cases among less than 1% of the population), significantly more child cases (i.e., below 15 years of age) were detected, indicating recent transmission. Cases in hotspots were not significantly more likely to be detected actively.

Conclusions

Leprosy showed a heterogeneous distribution with clear hotspots in northwest Bangladesh throughout a 20-year period of decreasing incidence. Findings confirm that leprosy hotspots represent areas of higher transmission activity and are not solely the result of active case finding strategies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40249-021-00817-4.

Incidence of and Factors Associated With Leprosy Among Household Contacts of Patients With Leprosy in Brazil

Importance

Despite progress toward reducing global incidence, leprosy control remains a challenge in low- and middle-income countries.

Objective

To estimate new case detection rates of leprosy among household contacts of patients with previously diagnosed leprosy and to investigate its associated risk factors.

Design, Setting, and Participants

This population-based cohort study included families registered in the 100 Million Brazilian Cohort linked with nationwide registries of leprosy; data were collected from January 1, 2007, through December 31, 2014. Household contacts of patients with a previous diagnosis of leprosy from each household unit were followed up from the time of detection of the primary case to the time of detection of a subsequent case or until December 31, 2014. Data analysis was performed from May to December 2018.

Exposures

Clinical characteristics of the primary case and sociodemographic factors of the household contact.

Main Outcomes and Measures

Incidence of leprosy, estimated as the new case detection rate of leprosy per 100 000 household contacts at risk (person-years at risk). The association between occurrence of a subsequent leprosy case and the exposure risk factors was assessed using multilevel mixed-effects logistic regressions allowing for state- and household-specific random effects.

Results

Among 42 725 household contacts (22 449 [52.5%] female; mean [SD] age, 22.4 [18.5] years) of 17 876 patients detected with leprosy, the new case detection rate of leprosy was 636.3 (95% CI, 594.4-681.1) per 100 000 person-years at risk overall and 521.9 (95% CI, 466.3-584.1) per 100 000 person-years at risk among children younger than 15 years. Household contacts of patients with multibacillary leprosy had higher odds of developing leprosy (adjusted odds ratio [OR], 1.48; 95% CI, 1.17-1.88), and the odds increased among contacts aged 50 years or older (adjusted OR, 3.11; 95% CI, 2.03-4.76). Leprosy detection was negatively associated with illiterate or preschool educational level (adjusted OR, 0.59; 95% CI, 0.38-0.92). For children, the odds were increased among boys (adjusted OR, 1.70; 95% CI, 1.20-2.42).

Conclusions and Relevance

The findings in this Brazilian population-based cohort study suggest that the household contacts of patients with leprosy may have increased risk of leprosy, especially in households with existing multibacillary cases and older contacts. Public health interventions, such as contact screening, that specifically target this population appear to be needed.

Leprosy: Treatment and management of complications

In the second article in this continuing medical education series, we review the treatment of leprosy, its immunologic reactions, and important concepts, including disease relapse and drug resistance. A fundamental understanding of the treatment options and management of neuropathic sequelae are essential to reduce disease burden and improve patients' quality of life.

New Developments in Bacterial, Viral, and Fungal Cutaneous Infections

PURPOSE OF REVIEW

This review highlights clinically relevant updates to common and significant bacterial, viral, and fungal cutaneous infection within the past 5 years. Recent developments are presented so that the clinician may provide evidence-based, high-quality patient care.

RECENT FINDINGS

New resistance patterns in cutaneous pathogens have recently emerged as a result of inappropriate antimicrobial use. Several new FDA-approved antimicrobials have been approved to treat such infections, including multi-drug resistant pathogens. Several organizational guidelines for cutaneous infection management have been updated with new recommendations for screening, diagnostic, and treatment strategies.

SUMMARY

Clinicians should be aware of the most recent evidence and guidelines for the management of cutaneous infections in order to reduce the emergence of antimicrobial resistance and most effectively treat their patients.

Predicting the impact of household contact and mass chemoprophylaxis on future new leprosy cases in South Tarawa, Kiribati: A modelling study

Background

The country of Kiribati is a small Pacific island nation which had a new case detection rate of 191 per 100,000 in 2016, and is one of the few countries yet to reach the WHO leprosy elimination goal. Chemoprophylaxis of household contacts of new cases, or to the whole population in a highly endemic areas have been found to be effective in reducing new case rates. This study investigated the potential impact of different chemoprophylaxis strategies on future cases in South Tarawa, the main population centre of Kiribati.

Methodology

The microsimulation model SIMCOLEP was calibrated to simulate the South Tarawa population and past leprosy control activities, and replicate annual new cases from 1989 to 2016. The impact of six different strategies for delivering one round of single dose rifampicin (SDR) chemoprophylaxis to household contacts of new cases and/or one or three rounds of SDR to the whole population was modelled from 2017 to 2030.

Principal Findings

Our model predicted that continuing the existing control program of high levels of public awareness, passive case detection, and treatment with multidrug treatment would lead to a substantial reduction in cases but this was less effective than all modelled intervention scenarios. Mass chemoprophylaxis led to a faster initial decline in cases than household contact chemoprophylaxis alone, however the decline under the latter was sustained for longer. The greatest cumulative impact was for household contact chemoprophylaxis with three rounds of mass chemoprophylaxis at one-year intervals.

Conclusions

The results suggest that control of leprosy would be achieved most rapidly with a combination of intensive population-based and household chemoprophylaxis. These findings may be generalisable to other countries where crowding places social contacts as well as household contacts of cases at risk of developing leprosy.

Leprosy rates in Kiribati are some of the highest in the world and it is one of the few countries yet to reach the World Health Organization leprosy elimination goal of a prevalence of less than one case per 10,000 population. The greatest burden is in the capital South Tarawa and the connected islet of Betio. Interest has increased for the use of chemoprophylaxis, the administration of preventive antibiotics to apparently healthy individuals who may be incubating the disease, which has been demonstrated to be effective in both household contacts and the whole population in two recent studies. In this study we used the individual-based model SIMCOLEP to predict the impact of six difference scenarios using single dose rifampicin (SDR) chemoprophylaxis in household contacts and/or the entire population on future new cases in South Tarawa. We found that all chemoprophylaxis strategies were predicted to be more effective than the current control strategy, particularly a combination of household contact chemoprophylaxis alongside three rounds given to the entire population in consecutive years.

Effectiveness of single-dose rifampicin after BCG vaccination to prevent leprosy in close contacts of patients with newly diagnosed leprosy: A cluster randomized controlled trial

OBJECTIVE

To assess the effectiveness of single-dose rifampicin (SDR) after bacillus Calmette-Guérin (BCG) vaccination in preventing leprosy in contacts.

METHODS

This was a single-centre, cluster-randomized controlled trial at a leprosy control programme in northwest Bangladesh. Participants were the 14988 contacts of 1552 new leprosy patients who were randomized into the SDR-arm (n=7379) and the SDR+arm (n=7609). In the intervention group, BCG vaccination was followed by SDR 8-12 weeks later. In the control group, BCG vaccination only was given. Follow-up was performed at 1year and 2 years after intake. The main outcome measure was the occurrence of leprosy.

RESULTS

The incidence rate per 10000 person-years at risk was 44 in the SDR-arm and 31 in the SDR+arm at 1year; the incidence rate was 34 in the SDR-arm and 41 in the SDR+arm at 2 years. There was a statistically non-significant (p=0.148; 42%) reduction for paucibacillary (PB) leprosy in the SDR+ arm at 1 year. Of all new cases, 33.6% appeared within 8-12 weeks after BCG vaccination.

CONCLUSIONS

In the first year, SDR after BCG vaccination reduced the incidence of PB leprosy among contacts by 42%. This was a statistically non-significant reduction due to the limited number of cases after SDR was administered. To what extent SDR suppresses excess leprosy cases after BCG vaccination is difficult to establish because many cases appeared before the SDR intervention.

TRIAL REGISTRATION

Netherlands Trial Register: NTR3087.

A novel integrated molecular and serological analysis method to predict new cases of leprosy amongst household contacts

Background

Early detection of Mycobacterium leprae is a key strategy for disrupting the transmission chain of leprosy and preventing the potential onset of physical disabilities. Clinical diagnosis is essential, but some of the presented symptoms may go unnoticed, even by specialists. In areas of greater endemicity, serological and molecular tests have been performed and analyzed separately for the follow-up of household contacts, who are at high risk of developing the disease. The accuracy of these tests is still debated, and it is necessary to make them more reliable, especially for the identification of cases of leprosy between contacts. We proposed an integrated analysis of molecular and serological methods using artificial intelligence by the random forest (RF) algorithm to better diagnose and predict new cases of leprosy.

Methods

The study was developed in Governador Valadares, Brazil, a hyperendemic region for leprosy. A longitudinal study was performed, including new cases diagnosed in 2011 and their respective household contacts, who were followed in 2011, 2012, and 2016. All contacts were diligently evaluated by clinicians from Reference Center for Endemic Diseases (CREDEN-PES) before being classified as asymptomatic. Samples of slit skin smears (SSS) from the earlobe of the patients and household contacts were collected for quantitative polymerase chain reaction (qPCR) of 16S rRNA, and peripheral blood samples were collected for ELISA assays to detect LID-1 and ND-O-LID.

Results

The statistical analysis of the tests revealed sensitivity for anti-LID-1 (63.2%), anti-ND-O-LID (57.9%), qPCR SSS (36.8%), and smear microscopy (30.2%). However, the use of RF allowed for an expressive increase in sensitivity in the diagnosis of multibacillary leprosy (90.5%) and especially paucibacillary leprosy (70.6%). It is important to report that the specificity was 92.5%.

Conclusion

The proposed model using RF allows for the diagnosis of leprosy with high sensitivity and specificity and the early identification of new cases among household contacts.

Leprosy is a chronic infectious disease caused by Mycobacterium leprae (M. leprae) that can infect cells in the skin and nerves. Despite efforts to eliminate leprosy, the number of M. leprae infected individuals who develop leprosy is still substantial in the world. The diagnosis relies mainly on clinical parameters. Histopathological and bacteriological analysis help to classify clinical forms of patients. Serology and polymerase chain reaction (PCR) assays are claimed by health professionals as auxiliary tools, but until now these tests have been used almost exclusively in research, with minor use in leprosy reference centers throughout Brazil. Here, we tested quantitative PCR (qPCR) designed to amplify specific M. leprae targets and ELISA assays to detect antibody response to recombinant antigens (LID-1, ND-O-LID). All results were analyzed by multivariate analysis based in artificial intelligence. We chose random forest as a classification algorithm to aid in the diagnosis and the monitoring of contacts. The results allowed us to diagnose cases of leprosy with high sensitivity and specificity and the early identification of new cases among household contacts.

Historical BCG vaccination combined with drug treatment enhances inhibition of mycobacterial growth ex vivo in human peripheral blood cells

Tuberculosis (TB) is a leading infectious cause of death globally. Drug treatment and vaccination, in particular with Bacillus Calmette-Guérin (BCG), remain the main strategies to control TB. With the emergence of drug resistance, it has been proposed that a combination of TB vaccination with pharmacological treatment may provide a greater therapeutic value. We implemented an ex vivo mycobacterial growth inhibition assay (MGIA) to discriminate vaccine responses in historically BCG-vaccinated human volunteers and to assess the contribution of vaccine-mediated immune response towards the killing effect of mycobacteria in the presence of the antibiotics isoniazid (INH) and rifampicin (RIF), in an attempt to develop the assay as a screening tool for therapeutic TB vaccines. BCG vaccination significantly enhanced the ability of INH to control mycobacterial growth ex vivo. The BCG-vaccinated group displayed a higher production of IFN-γ and IP-10 when peripheral blood mononuclear cells (PBMC) were co-cultured with INH, with a similar trend during co-culture with RIF. A higher frequency of IFN-γ⁺ and TNF-α⁺ CD3⁻ CD4⁻ CD8⁻ cells was observed, suggesting the contribution of Natural Killer (NK) cells in the combined effect between BCG vaccination and INH. Taken together, our data indicate the efficacy of INH can be augmented following historical BCG vaccination, which support findings from previous observational and animal studies.

Leprosy: A great imitator

In recent years, advances in medical diagnosis and treatment have greatly attracted our attention, whereas some rare diseases, such as leprosy, have not found a place in the medical education curriculum; their existence may even be forgotten. Although the prevalence and incidence rates for leprosy have been significantly reduced as a result of the control strategies of the World Health Organization, new cases still appear. A total of 214,783 new cases were reported from 143 countries during 2016, corresponding to the global new-case detection rate of 2.9 per 100,000 population. Leprosy proves to be a very interesting model due to its immunologic properties. It joins with syphilis, mycosis fungoides, cutaneous tuberculosis, and sarcoidosis as one of the great imitators. The diagnosis of leprosy can be simple and practical, but considering the diagnosis of leprosy in the differential diagnosis is the first requisite again.

Trend analysis of leprosy in Morocco between 2000 and 2017: Evidence on the single dose rifampicin chemoprophylaxis

Background

Morocco has achieved the goal of leprosy elimination as a public health problem several years ago (less than 1 case/ 10 000 habitant). The aim of this study was to analyze trends of leprosy detection during the last 17 years taking into consideration the implementation of single dose rifampicin chemoprophylaxis (SDRC) started in 2012.

Methodology

Time series of leprosy cases detected at national level between 2000 and 2017. Variable collected for each year were leprosy per 100000 H, age category, gender, origin, regions, grade of disabilities and clinical forms. The detection time series was assessed by Joinpoint Regression Analysis. Annual percentage changes (APCs) were estimated to identify the years (joinpoint) when significant changes occurred in the trend. We therefore examined trends in leprosy detection according to epidemiological variables.

Findings

Joinpoint regression showed a reduction in the detection rate between 2000 and 2017. The APC for the period 2012–2017 (-16.83, 95% CI: -29.2 to -2.3, p <0.05) was more pronounced than that of the previous period 2000–2012 (- 4.68, 95% CI: -7.3 to -2.0, p <0.05); with a significant break in the same joinpoint year SDRC implementation. In stratified analysis, case detection decreased, but not significantly, after the joinpoint years in men, children, multi-bacillary cases, grade 0–1 disabilities, rural and urban cases and in ten regions.

Conclusions

Leprosy detection was declining over years with a significant reduction by 16% per year from 2012 to 2017. SDRC may reduce leprosy detection over the years following its administration.

After the introduction of effective therapy for leprosy by the world health organization in early eighties, there has been a marked reduction in new case detection all over the world. Despite the decline in case detection of leprosy, incidence reduction to zero and suppression of infection source is still not possible. Addressed strategies to high-risk groups–contacts of leprosy cases- may be effective to eliminate the disease at global level. Chemoprophylaxis in contacts may lower the incidence of leprosy in contacts of patients diagnosed with leprosy. In Morocco, chemoprophylaxis was introduced at national level in 2012. Morocco has achieved the goal of leprosy elimination as a public health problem in 1991 and the declining trend of leprosy detection is observed years after years. However, no study has been conducted in the country to analyze whether the declining trend of leprosy can be related or not to chemoprophylaxis in contact. This time series can be of interest for medical community as the authors analyses the trend in leprosy in the last 17 years and try to generate a hypothesis about any relationship with chemoprophylaxis implementation.

Population-wide administration of single dose rifampicin for leprosy prevention in isolated communities: a three year follow-up feasibility study in Indonesia

BACKGROUND

Indonesia ranking third in the world, regarding leprosy burden. Chemoprophylaxis is effective in reducing risk of developing leprosy among contacts. 'Blanket approach' is an operational strategy for leprosy post-exposure prophylaxis in which all members of an isolated community, high endemic for leprosy are screened and given a single dose of rifampicin (SDR) in the absence of signs and symptoms of leprosy. The objective is to assess the operational feasibility of a population-wide 'blanket' administration of SDR for leprosy prevention in isolated communities in a remote island.

METHODS

A prospective follow-up study was conducted in the year 2014, 2015 and 2016 in Lingat village of Selaru Island, Indonesia. During the first two visits, screening and SDR were provided, whereas only screening was conducted during the third visit. The demographic and clinical data were used for a descriptive analysis of the project coverage and leprosy epidemiology.

RESULTS

During the first two visits, 1671 persons (88%) were screened, 1499 (79%) received SDR, and 213 (11%) were excluded based on the exclusion criteria. During the first two visits, 43 (2.6%) cases were diagnosed with leprosy with a rate of 2263 per 100,000 population. The prevalence was highest in the age groups 15-24 and 25-49 years. Total, 14 (33%) cases had MB and 29 (67%) PB leprosy. Two cases (5%) had grade 2 disability. During the third visit, 10 new leprosy cases, with no grade 2 disability, were detected out of 1481 screened persons at the rate of 484 cases per 100,000 population (n = 2065 population in 2016). Among those screened during the third visit, there was a 50% reduction of leprosy among those who had previously received SDR compared to those who had not.

CONCLUSION

With adequate planning and some additional investment, it is feasible to implement a blanket approach of chemoprophylaxis in a remote island of Indonesia, although effort needs to be made to cover as many people as possible in the first visit. Contingency plans need to be made to actively follow this village closely in the coming years and continue leprosy elimination efforts until no new cases are found any more.

Leprosy among schoolchildren in the Amazon region: A cross-sectional study of active search and possible source of infection by contact tracing

Background

The high rate of leprosy cases among children under 15 years of age in Brazil indicates ongoing transmission within the community. The identification of the new leprosy cases among contacts can help identify the source of infection and interrupt the transmission chain. This study aims to determine the detection rate of previously undiagnosed cases of leprosy among schoolchildren who are under 15 years of age living in Manaus, Amazonas, Brazil, and their possible source of infection by contact tracing.

Methodology/Principal findings

This was a school-based, cross-sectional study in which the identification of active leprosy cases was conducted in 277 out of 622 randomly selected public schools in Manaus, Amazonas, Brazil. Suspected cases of leprosy were referred to the Alfredo da Matta Foundation, a reference center for leprosy in Manaus. A total of 34,547 schoolchildren were examined, and 40 new leprosy cases were diagnosed. Among new cases, 57.5% were males, and 80.0% demonstrated paucibacillary leprosy. A total of 196 of 206 registered contacts were screened, and 52.5% of the newly diagnosed children’s cases had at least one positive household contact. In these contacts, grandparents (52.4%) were the most common co-prevalent cases, while 14.3% were uncles, 9.5% were parents and 9.5% were granduncles. Seven contacts (5.0%), including four siblings of child patients were newly diagnosed. Our data indicate that the prevalence is 11.58 per 10,000, which is 17 times higher than the registered rate.

Conclusions/Significance

This study suggests that the detection rate of leprosy among schoolchildren may have remained unchanged over the past thirty years. It also indicates that that active case finding is necessary for reaching the World Health Organization’s goals of zero detection among children, especially in endemic areas where the prevalence of leprosy is obscure. Moreover, we assert that all children must have their household contacts examined in order to identify the possible source of infection and interrupt the disease’s transmission. Novel strategies to reinforce contact tracing associated with large-scale strategies of chemo- and immune-prophylaxis should be expanded to prevent the perpetuation of the disease cycle.

Leprosy is a disease that has long since been eradicated in the developed world, but it still affects poor people in developing countries, such as India, Brazil, and Indonesia. Because the causative agent of the disease may involve the skin and peripheral nerves, the disease can cause physical disabilities and deformities. Although leprosy affects all ages, children under 15 years of age are an important epidemiological marker because infection in that age group indicates active transmission within the community. In our work, we examined 34,547 children from public schools in Manaus, a city in the north of Brazil. In this population, we found 40 new cases of leprosy that were further confirmed by clinical and laboratorial tests. We also examined 196 people who had familiar or close non-familiar contact with the affected children. Among them, we identified the possible source of infection of 21 affected children and found seven new cases of leprosy. Overall, our findings revealed a detection rate of leprosy cases that was 17 times higher than the registered number. This indicates the necessity of identifying active cases of leprosy in order to improve case detection and effectively control the disease.

Vaccines for Leprosy and Tuberculosis: Opportunities for Shared Research, Development, and Application

Tuberculosis (TB) and leprosy still represent significant public health challenges, especially in low- and lower middle-income countries. Both poverty-related mycobacterial diseases require better tools to improve disease control. For leprosy, there has been an increased emphasis on developing tools for improved detection of infection and early diagnosis of disease. For TB, there has been a similar emphasis on such diagnostic tests, while increased research efforts have also focused on the development of new vaccines. Bacille Calmette–Guérin (BCG), the only available TB vaccine, provides insufficient and inconsistent protection to pulmonary TB in adults. The impact of BCG on leprosy, however, is significant, and the introduction of new TB vaccines that might replace BCG could, therefore, have serious impact also on leprosy. Given the similarities in antigenic makeup between the pathogens Mycobacterium tuberculosis (Mtb) and M. leprae, it is well possible, however, that new TB vaccines could cross-protect against leprosy. New TB subunit vaccines currently evaluated in human phase I and II studies indeed often contain antigens with homologs in M. leprae. In this review, we discuss pre-clinical studies and clinical trials of subunit or whole mycobacterial vaccines for TB and leprosy and reflect on the development of vaccines that could provide protection against both diseases. Furthermore, we provide the first preclinical evidence of such cross-protection by Mtb antigen 85B (Ag85B)-early secretory antigenic target (ESAT6) fusion recombinant proteins in in vivo mouse models of Mtb and M. leprae infection. We propose that preclinical integration and harmonization of TB and leprosy research should be considered and included in global strategies with respect to cross-protective vaccine research and development.

Immunomodulatory Therapy of Visceral Leishmaniasis in Human Immunodeficiency Virus-Coinfected Patients

Patients with visceral leishmaniasis (VL)–human immunodeficiency virus (HIV) coinfection experience increased drug toxicity and treatment failure rates compared to VL patients, with more frequent VL relapse and death. In the era of VL elimination strategies, HIV coinfection is progressively becoming a key challenge, because HIV-coinfected patients respond poorly to conventional VL treatment and play an important role in parasite transmission. With limited chemotherapeutic options and a paucity of novel anti-parasitic drugs, new interventions that target host immunity may offer an effective alternative. In this review, we first summarize current views on how VL immunopathology is significantly affected by HIV coinfection. We then review current clinical and promising preclinical immunomodulatory interventions in the field of VL and discuss how these may operate in the context of a concurrent HIV infection. Caveats are formulated as these interventions may unpredictably impact the delicate balance between boosting of beneficial VL-specific responses and deleterious immune activation/hyperinflammation, activation of latent provirus or increased HIV-susceptibility of target cells. Evidence is lacking to prioritize a target molecule and a more detailed account of the immunological status induced by the coinfection as well as surrogate markers of cure and protection are still required. We do, however, argue that virologically suppressed VL patients with a recovered immune system, in whom effective antiretroviral therapy alone is not able to restore protective immunity, can be considered a relevant target group for an immunomodulatory intervention. Finally, we provide perspectives on the translation of novel theories on synergistic immune cell cross-talk into an effective treatment strategy for VL–HIV-coinfected patients.

Introducing leprosy post-exposure prophylaxis into the health systems of India, Nepal and Indonesia: a case study

Background

Leprosy has a wide range of clinical and socio-economic consequences. India, Indonesia and Nepal contribute significantly to the global leprosy burden. After integration, the health systems are pivotal in leprosy service delivery. The Leprosy Post Exposure Prophylaxis (LPEP) program is ongoing to investigate the feasibility of providing single dose rifampicin (SDR) as post-exposure prophylaxis (PEP) to the contacts of leprosy cases in various health systems. We aim to compare national leprosy control programs, and adapted LPEP strategies in India, Nepal and Indonesia. The purpose is to establish a baseline of the health system’s situation and document the subsequent adjustment of LPEP, which will provide the context for interpreting the LPEP results in future.

Methods

The study followed the multiple-case study design with single units of analysis. The data collection methods were direct observation, in-depth interviews and desk review. The study was divided into two phases, i.e. review of national leprosy programs and description of the LPEP program. The comparative analysis was performed using the WHO health system frameworks (2007).

Results

In all countries leprosy services including contact tracing is integrated into the health systems. The LPEP program is fully integrated into the established national leprosy programs, with SDR and increased documentation, which need major additions to standard procedures. PEP administration was widely perceived as well manageable, but the additional LPEP data collection was reported to increase workload in the first year.

Conclusions

The findings of our study led to the recommendation that field-based leprosy research programs should keep health systems in focus. The national leprosy programs are diverse in terms of organizational hierarchy, human resource quantity and capacity. We conclude that PEP can be integrated into different health systems without major structural and personal changes, but provisions are necessary for the additional monitoring requirements.

Electronic supplementary material

The online version of this article (10.1186/s12913-017-2611-7) contains supplementary material, which is available to authorized users.

Opening a Can of Worms: Leprosy Reactions and Complicit Soil-Transmitted Helminths

Background

> 94% of new annual leprosy cases are diagnosed in populations co-endemic for soil-transmitted helminths (STH). STH can profoundly dysregulate host immune responses towards Th2 bias, which can be restored over time after deworming. We hypothesize that STH co-infection is associated with leprosy reaction (denoted as simply “reaction” herein) occurrence within a co-endemic population.

Methods

A cohort study was performed on a cohort of Nepalese leprosy patients across treatment and diagnostic classifications who were screened by routine fecal smear microscopy and multiplex quantitative PCR (qPCR) for Ascaris lumbricoides (Al), Strongyloides stercoralis (Ss), Ancyclostoma duodenale (Ad) and Necator americanus (Na).

Results

Among 145 patients, 55% were positive for ≥ 1 STH (STH +): 34% Al +, 18% Ss +, 17% Ad + and 5% Na +. Significant inverse STH and reaction relationships were evidenced by the bulk of cases: 63% reaction-negative were STH + of total cases (p = 0.030) while 65% reaction-positive were STH − in new cases (96; p = 0.023). Strikingly, the majority of STH + were reaction-negative, even when considering each species: 59% Al +, 60% Ss +, 62% Ad + and 67% Na + of new leprosy cases.

Conclusions

Absence of STH co-infection is associated with leprosy reaction at diagnosis within a co-endemic population. This is likely due to immune reconstitution effects after deworming or interruption of chronic STH-mediated immune dysregulation.

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Fecal screening by qPCR revealed that 55% of 145 leprosy patients hosted 1 or more soil-transmitted helminth (STH) co-infections

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STH coinfection was significantly and inversely associated with leprosy reaction

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Chronic STH-induced immune bias followed by disruption of co-infection, potentially by deworming, may initiate immune reconstitution that can lead to reaction development

Leprosy in Children

PURPOSE OF REVIEW

This manuscript aims to review the cutting-edge developments regarding to the diagnosis, management, and prevention of leprosy in children.

RECENT FINDINGS

Leprosy transmission still occurs continuously in some endemic areas in the world. Leprosy in children below 15 years old is a robust indicator of active source of infection in the community where they live. A special focus on children to reduce disabilities and reduce transmission is one of the core areas of interventions of the global leprosy strategy 2016-2020. Ongoing research is trying to develop better diagnostic tests and to advance chemoprophylaxis and immunoprophylaxis approaches. Early diagnosis in children can be hard because of the wide range of clinical aspects of the skin lesions and mainly due to the difficulty of performing the clinical peripheral nerve evaluation. We must maintain leprosy expertise and improve the health professionals training for leprosy diagnosis, since we still have a long journey to reach leprosy elimination.

Spatial heterogeneity in projected leprosy trends in India

BACKGROUND

Leprosy is caused by infection with Mycobacterium leprae and is characterized by peripheral nerve damage and skin lesions. The disease is classified into paucibacillary (PB) and multibacillary (MB) leprosy. The 2012 London Declaration formulated the following targets for leprosy control: (1) global interruption of transmission or elimination by 2020, and (2) reduction of grade-2 disabilities in newly detected cases to below 1 per million population at a global level by 2020. Leprosy is treatable, but diagnosis, access to treatment and treatment adherence (all necessary to curtail transmission) represent major challenges. Globally, new case detection rates for leprosy have remained fairly stable in the past decade, with India responsible for more than half of cases reported annually.

METHODS

We analyzed publicly available data from the Indian Ministry of Health and Family Welfare, and fit linear mixed-effects regression models to leprosy case detection trends reported at the district level. We assessed correlation of the new district-level case detection rate for leprosy with several state-level regressors: TB incidence, BCG coverage, fraction of cases exhibiting grade 2 disability at diagnosis, fraction of cases in children, and fraction multibacillary.

RESULTS

Our analyses suggest an endemic disease in very slow decline, with substantial spatial heterogeneity at both district and state levels. Enhanced active case finding was associated with a higher case detection rate.

CONCLUSIONS

Trend analysis of reported new detection rates from India does not support a thesis of rapid progress in leprosy control.

Global elimination of leprosy by 2020: are we on track?

BACKGROUND

Every year more than 200,000 new leprosy cases are registered globally. This number has been fairly stable over the past 8 years. WHO has set a target to interrupt the transmission of leprosy globally by 2020. The aim of this study is to investigate whether this target, interpreted as global elimination, is feasible given the current control strategy. We focus on the three most important endemic countries, India, Brazil and Indonesia, which together account for more than 80 % of all newly registered leprosy cases.

METHODS

We used the existing individual-based model SIMCOLEP to predict future trends of leprosy incidence given the current control strategy in each country. SIMCOLEP simulates the spread of M. leprae in a population that is structured in households. Current control consists of passive and active case detection, and multidrug therapy (MDT). Predictions of leprosy incidence were made for each country as well as for one high-endemic region within each country: Chhattisgarh (India), Pará State (Brazil) and Madura (Indonesia). Data for model quantification came from: National Leprosy Elimination Program (India), SINAN database (Brazil), and Netherlands Leprosy Relief (Indonesia).

RESULTS

Our projections of future leprosy incidence all show a downward trend. In 2020, the country-level leprosy incidence has decreased to 6.2, 6.1 and 3.3 per 100,000 in India, Brazil and Indonesia, respectively, meeting the elimination target of less than 10 per 100,000. However, elimination may not be achieved in time for the high-endemic regions. The leprosy incidence in 2020 is predicted to be 16.2, 21.1 and 19.3 per 100,000 in Chhattisgarh, Pará and Madura, respectively, and the target may only be achieved in another 5 to 10 years.

CONCLUSIONS

Our predictions show that although country-level elimination is reached by 2020, leprosy is likely to remain a problem in the high-endemic regions (i.e. states, districts and provinces with multimillion populations), which account for most of the cases in a country.

Laryngeal involvement causing dysphonia in a 29 year old nursing mother with lepromatous leprosy

Leprosy is a granulomatous disease that mainly affects the skin and peripheral nerves. It is caused by infection with mycobacterium leprae or mycobacterium lepromatosus. In most instances, diagnosis of leprosy can easily be made based on the clinical signs and symptoms. However, when patients present with atypical features, clinical diagnosis can be a challenge. We report a case of a nursing mother with lepromatous leprosy who presented with dysphonia and skin lesions initially thought to be a deep cutaneous mycosis.

Clinical manifestations of leprosy after BCG vaccination: an observational study in Bangladesh

BACKGROUND

Although BCG is used as a vaccine against tuberculosis, it also protects against leprosy. Previous evaluation over 18 years of an intervention of two doses BCG for 3536 household contacts of leprosy patients showed that 28 (23%) out of 122 contacts diagnosed with leprosy, developed symptoms 2-10 months after vaccination. This study describes contacts of leprosy patients in Bangladesh who developed leprosy within 12 weeks after receiving a single BCG dose.

METHODS

A cluster RCT in Bangladesh aims to study the effectiveness of the BCG vaccine versus BCG in combination with single dose rifampicin (SDR) given 2 to 3 months after BCG, in the prevention of leprosy among contacts of newly diagnosed leprosy patients. During the first 1,5 years of this ongoing trial we identified contacts who developed leprosy within the first 12 weeks after receiving BCG vaccination, the timeframe before SDR is given.

RESULTS

We identified 21 contacts who developed leprosy within 12 weeks after BCG vaccination among 5196 vaccinated contacts (0.40%). All 21 cases presented with paucibacillary (PB) leprosy, including children and adults. About half of these cases had previously received BCG vaccination as indicated by the presence of a BCG scar; 43% presented with signs of nerve function impairment and/or Type 1 (reversal) reaction, and 56% of the index patients had multibacillary (MB) leprosy.

CONCLUSION

An unexpectedly high proportion of healthy contacts of leprosy patients presented with PB leprosy within 12 weeks after receiving BCG vaccination, possibly as a result of boosted cell-mediated immunity by homologues of Mycobacterium leprae antigens in BCG. Various immunological mechanisms could underlie this phenomenon, including an immune reconstitution inflammatory syndrome (IRIS). Further studies are required to determine whether BCG vaccination merely altered the incubation period or actually changed the course of the infection from self-limiting, subclinical infection to manifest disease.

Effectiveness of routine BCG vaccination on buruli ulcer disease: a case-control study in the Democratic Republic of Congo, Ghana and Togo

Background

The only available vaccine that could be potentially beneficial against mycobacterial diseases contains live attenuated bovine tuberculosis bacillus (Mycobacterium bovis) also called Bacillus Calmette-Guérin (BCG). Even though the BCG vaccine is still widely used, results on its effectiveness in preventing mycobacterial diseases are partially contradictory, especially regarding Buruli Ulcer Disease (BUD). The aim of this case-control study is to evaluate the possible protective effect of BCG vaccination on BUD.

Methodology

The present study was performed in three different countries and sites where BUD is endemic: in the Democratic Republic of the Congo, Ghana, and Togo from 2010 through 2013. The large study population was comprised of 401 cases with laboratory confirmed BUD and 826 controls, mostly family members or neighbors.

Principal Findings

After stratification by the three countries, two sexes and four age groups, no significant correlation was found between the presence of BCG scar and BUD status of individuals. Multivariate analysis has shown that the independent variables country (p = 0.31), sex (p = 0.24), age (p = 0.96), and presence of a BCG scar (p = 0.07) did not significantly influence the development of BUD category I or category II/III. Furthermore, the status of BCG vaccination was also not significantly related to duration of BUD or time to healing of lesions.

Conclusions

In our study, we did not observe significant evidence of a protective effect of routine BCG vaccination on the risk of developing either BUD or severe forms of BUD. Since accurate data on BCG strains used in these three countries were not available, no final conclusion can be drawn on the effectiveness of BCG strain in protecting against BUD. As has been suggested for tuberculosis and leprosy, well-designed prospective studies on different existing BCG vaccine strains are needed also for BUD.

After tuberculosis and leprosy, Buruli Ulcer Disease (BUD) is the third most common human mycobacterial disease. The only available vaccine that could be potentially beneficial against these diseases is BCG. Even though BCG vaccine is widely used, the results on its effectiveness are partially contradictory, probably since different BCG strains are used. The aim of this study was to evaluate the possible protective effect of BCG vaccines on BUD. The present study was performed in three different countries and sites where BUD is endemic: in the Democratic Republic of the Congo, Ghana, and Togo from 2010 through 2013. The large study population was comprised of 401 cases with laboratory confirmed BUD and 826 controls, mostly family members or neighbors. Considering the three countries, sex, and age, the analysis confirmed that the BCG vaccination did not significantly decrease the risk for developing BUD or for developing severe forms of BUD. Furthermore, the status of BCG vaccination was also not significantly related to duration of BUD or to time to healing of lesions. In our study, we could not find any evidence of a protective effect of routine BCG vaccination on BUD.

Worms and Humans: A Happy Divorce?

Chronic asymptomatic worm infection, often in combination with tuberculosis (TB), is common in low-income countries. Indeed, a life without worm infestation, as is now the case in most high-income countries, is a recent condition for humankind. Worms and Mycobacterium tuberculosis give rise to different immune response patterns (Th2 vs. Th1 driven), and we have studied whether chronic worm infection affects the susceptibility to and control of TB in the low income country of Ethiopia. Our results, as well of those in the general literature, are inconclusive, although we have some rather strong data in support of adult deworming in relation to vaccination with bacillus Calmette-Guérin (BCG) against TB. In addition, we discuss briefly the putative relationship between chronic worm infestation and autoimmunity/allergy.

The combined effect of chemoprophylaxis with single dose rifampicin and immunoprophylaxis with BCG to prevent leprosy in contacts of newly diagnosed leprosy cases: a cluster randomized controlled trial (MALTALEP study)

Background

Despite almost 30 years of effective chemotherapy with MDT, the global new case detection rate of leprosy has remained quite constant over the past years. New tools and methodologies are necessary to interrupt the transmission of M. leprae. Single-dose rifampicin (SDR) has been shown to prevent 57% of incident cases of leprosy in the first two years, when given to contacts of newly diagnosed cases. Immunization of contacts with BCG has been less well documented, but appears to have a preventive effect lasting up to 9 years. However, one major disadvantage is the occurrence of excess cases within the first year after immunization. The objective of this study is to examine the effect of chemoprophylaxis with SDR and immunoprophylaxis with BCG on the clinical outcome as well as on host immune responses and gene expression profiles in contacts of newly diagnosed leprosy patients. We hypothesize that the effects of both interventions may be complementary, causing the combined preventive outcome to be significant and long-lasting.

Methods/design

Through a cluster randomized controlled trial we compare immunization with BCG alone with BCG plus SDR in contacts of new leprosy cases. Contact groups of around 15 persons will be established for each of the 1300 leprosy patients included in the trial, resulting in approximately 20,000 contacts in total. BCG will be administered to the intervention group followed by SDR, 2 months later. The control group will receive BCG only. In total 10,000 contacts will be included in both intervention arms over a 2-year period. Follow-up will take place one year as well as two years after intake. The primary outcome is the occurrence of clinical leprosy within two years. Simultaneously with vaccination and SDR, blood samples for in vitro analyses will be obtained from 300 contacts participating in the trial to determine the effect of these chemo- and immunoprophylactic interventions on immune and genetic host parameters.

Discussion

Combined chemoprophylaxis and immunoprophylaxis is potentially a very powerful and innovative tool aimed at contacts of leprosy patients that could reduce the transmission of M. leprae markedly. The trial intends to substantiate this potential preventive effect. Evaluation of immune and genetic biomarker profiles will allow identification of pathogenic versus (BCG-induced) protective host biomarkers and could lead to effective prophylactic interventions for leprosy using optimized tools for identification of individuals who are most at risk of developing disease.

Trial registration

Netherlands Trial Register: NTR3087