BCG revaccination does not protect against leprosy in the Brazilian Amazon: a cluster randomised trial

Protective effects of BCG vaccination against multibacillary disease, reactions, and disabilities in childhood leprosy: Insights from a retrospective observational study from a tertiary care center in India

BACKGROUND AND METHODS

While leprosy primarily affects adults, childhood leprosy poses unique challenges because of its potential to cause lifelong disabilities and stigma. This is a retrospective record review of all patients aged 15 or below, diagnosed with leprosy, who were registered at the leprosy clinic of our tertiary care center from June 2014 to December 2023.

RESULTS

As per hospital records, 1083 leprosy cases were registered at our center during the study period. Of these, 50 (4.6%) were children below 15 years of age. Persistent skin lesions (PSL) were seen in 11 (22%) cases, and the most common spectrum in which PSL were seen was the bordeline tuberculoid spectrum (BT) (7/11; 63.6%). Among these cases, a Bacillus Calmette-Guerin (BCG) scar was present in only four (36.4%) patients. Overall, a BCG scar was noted in 39/50 cases (78%). The relationship between having no BCG scar and multibacillary disease, lepromatous leprosy (LL), or the borderline lepromatous (BL) spectrum was statistically significant (P = 0.021). Of the six reaction cases, only one patient had a BCG scar (2%). A statistically significant association was found between the absence of a BCG scar and having a reaction (P < 0.01). Of the 11 grade 2 disability cases, nine cases (all within the BL or LL spectrum) had no BCG scar, which was also statistically significant (P < 0.01).

CONCLUSIONS

Further research is warranted to strengthen the evidence of the impact of vaccination [BCG/Mycobacterium indicus pranii (MIP)] on the patterns of childhood leprosy, its effect on PSL, and its role in the prevention of reactions and disabilities. Such research would also help in optimizing strategies for the vaccine's universal application.

Efficacy of leprosy vaccines across the globe: A systematic review & meta-analysis of randomized controlled trials

Background & objectives Although multi-drug therapy has decreased the burden of disease, leprosy is yet to be eliminated. Accelerating progress requires optimal use of existing tools, advanced diagnostic tests, newer drugs, and vaccines. The search for a vaccine with therapeutic and preventive potential is ongoing, but evidence on effectiveness and safety is lacking. This systematic review and meta-analysis will evaluate and compare the clinical efficacy, immunogenicity, and safety of leprosy vaccines in humans. Methods In June 2024, three databases were systematically searched with updated search keywords. Randomized controlled trials (RCTs) pertaining to leprosy vaccines for humans which evaluated either therapeutic or prophylactic vaccines in leprosy with a placebo or active comparator arm, with full-text access, were included in the study. There were no restrictions on language, country or date. For the risk of bias assessment in the studies included, the revised Cochrane risk-of-bias 2 tool for RCTs was used. A P value (two-sided) of <0.05 was considered as significant for all tests; however for heterogeneity, a one-sided P value of <0.1 was considered as statistically significant. The quality of generated evidence specific to the desired outcomes were assessed using the GRADE approach (Grading of Recommendations Assessment, Development and Evaluation). The study protocol was registered in PROSPERO (ID: CRD42024561651). Results A total of 2163 studies were retrieved from different databases. After removing duplicates and full text screening, 12 articles were finally selected. Out of these studies, eight used leprosy vaccines on prophylactic basis, while four used leprosy vaccines on therapeutic basis. In therapeutic use of leprosy vaccine, Ramu's score was found to be significantly protective [-3.06 (95% confidence interval (CI): -3.96 to -2.16)] among the recipients of the therapeutic leprosy vaccine. Bacterial index was found to be insignificant [-0.26 (95% CI: -1.54 to 1.03)] among the recipients of therapeutic leprosy vaccine. In subgroup analysis among the eight prophylactic vaccine studies, pooled relative risk was found to be 0.61 (95% CI: 0.41 - 0.91). Interpretation & conclusions The findings of this meta-analysis suggest that both prophylactic and therapeutic leprosy vaccines were significantly better compared to the placebo. Leprosy vaccine in the form of Mw/Mycobacterium welchii/MIP along with combination of World Health Organization (WHO) multi-drug therapy (MDT) or Bacillus Calmette-Guerin (BCG) vaccine along with second line treatment with rifampicin were found to be protective among the recipients.

Leprosy

Leprosy, a neglected tropical disease, causes significant morbidity in marginalized communities. Before the COVID-19 pandemic, annual new case detection plateaued for over a decade at ~200,000 new cases. The clinical phenotypes of leprosy strongly parallel host immunity to its causative agents Mycobacterium leprae and Mycobacterium lepromatosis. The resulting spectrum spans from paucibacillary leprosy, characterized by vigorous pro-inflammatory immunity with few bacteria, to multibacillary leprosy, harbouring large numbers of bacteria with high levels of seemingly non-protective, anti-M. leprae antibodies. Leprosy diagnosis remains clinical, leaving asymptomatic individuals with infection undetected. Antimicrobial treatment is effective with recommended multidrug therapy for 6 months for paucibacillary leprosy and 12 months for multibacillary leprosy. The incubation period ranges from 2 to 6 years, although longer periods have been described. Given this lengthy incubation period and dwindling clinical expertise, there is an urgent need to create innovative, low-complexity diagnostic tools for detection of M. leprae infection. Such advancements are vital for enabling swift therapeutic and preventive interventions, ultimately transforming patient outcomes. National health-care programmes should prioritize early case detection and consider post-exposure prophylaxis for individuals in close contact with affected persons. These measures will help interrupt transmission, prevent disease progression, and mitigate the risk of nerve damage and disabilities to achieve the WHO goal 'Towards Zero Leprosy' and reduce the burden of leprosy.

The Association Between Bacille Calmette-Guérin Vaccination and Nontuberculous Mycobacterial Pulmonary Disease

This study aimed to investigate the association between Bacille Calmette-Guérin (BCG) vaccination and nontuberculous mycobacterial pulmonary disease (NTM-PD). Patients in the prospective NTM-PD cohort were matched to healthy controls to measure the association between BCG and NTM-PD development. The clinical course of NTM-PD patients was also evaluated to investigate the association between BCG and NTM-PD progression. BCG scars were not associated with NTM-PD development (adjusted odds ratio [OR], 2.04; 95% confidence interval [CI], 0.96-4.34) or progression (adjusted OR, 1.61; 95% CI, 0.92-2.81). In conclusion, BCG vaccination was not associated with the development or progression of NTM-PD.

Revaccination with Bacille Calmette-Guérin (BCG) is associated with an increased risk of abscess and lymphadenopathy

The reported frequency and types of adverse events following initial vaccination and revaccination with Bacille Calmette-Guérin (BCG) varies worldwide. Using active surveillance in a randomised controlled trial of BCG vaccination (the BRACE trial), we determined the incidence and risk factors for the development of BCG injection site abscess and regional lymphadenopathy. Injection site abscess occurred in 3% of 1387 BCG-vaccinated participants; the majority (34/41, 83%) resolved without treatment. The rate was higher in BCG-revaccinated participants (OR 3.6, 95% CI 1.7-7.5), in whom abscess onset was also earlier (median 16 vs. 27 days, p = 0.008). No participant with an abscess had a positive interferon-gamma release assay. Regional lymphadenopathy occurred in 48/1387 (3%) of BCG-vaccinated participants, with a higher rate in revaccinated participants (OR 2.1, 95% CI 1.1-3.9). BCG-associated lymphadenopathy, but not injection site abscess, was influenced by age and sex. A previous positive tuberculin skin test was not associated with local reactions. The increased risk of injection site abscess or lymphadenopathy following BCG revaccination is relevant to BCG vaccination policy in an era when BCG is increasingly being considered for novel applications.

BCG re-vaccination in Malawi: 30-year follow-up of a large, randomised, double-blind, placebo-controlled trial

BACKGROUND

A large, double-blind, randomised, placebo-controlled trial of repeat BCG found 49% efficacy against leprosy but no protection against tuberculosis after 6-9 years' follow-up in 1995. We report here additional follow-up, which resulted in greatly increased tuberculosis case numbers, and allowed subgroup analysis.

METHODS

Nearly 47 000 individuals of all ages living in northern Malawi with a BCG vaccine scar were randomly assigned (1:1) between 1986 and 1989 to receive a second BCG or placebo. The investigators and project staff remained masked to all interventions. Enhanced passive surveillance ensured ascertainment of tuberculosis and leprosy to the end of 2018. Tuberculosis case definitions included rigorous microbiological or histological confirmation. Prespecified subgroup analyses were by tuberculosis type, age at vaccination, time since vaccination, previous tuberculin reactivity, HIV status and Mycobacterium tuberculosis lineage. The original trial is registered with ISRCTN registry, ISRCTN11311670.

FINDINGS

In follow-up until Dec 31, 2018, 824 participants had developed tuberculosis, including 786 with pulmonary disease, of whom 383 (63%) of 607 with known HIV status were HIV positive. There was no effect of a second BCG overall (odds ratio [OR] 0·92; 95% CI 0·80-1·05), or for pulmonary (0·93; 0·81-1·07), or lymph node tuberculosis (0·60; 0·31-1·17). The OR was lower for those with known HIV-negative tuberculosis (0·77; 0·59-1·00), for those vaccinated as children (aged <5 years, 0·74; 0·41-1·35; aged 5-14 years, 0·77; 0·60-0·99), and for cases arising at least 20 years after vaccination (0·79; 0·63-1·01). There were no differences by tuberculin status at vaccination, or lineage. There was no evidence of protection against leprosy beyond 10 years after vaccination (although there have been only nine diagnostically certain cases since 1995).

INTERPRETATION

There was no evidence that repeat BCG vaccination provides appreciable protection against overall tuberculosis in this rural African population with a high prevalence of HIV. Subgroup effects should not be overinterpreted given the multiple analyses done. However, the evidence for modest protection against HIV-negative tuberculosis, and for a delayed benefit in those vaccinated as children, is consistent with other observations in the literature.

FUNDING

LEPRA, Wellcome Trust, Bill & Melinda Gates Foundation.

Efficacy of chemoprophylaxis and immunoprophylaxis in leprosy prevention: a systematic review and network meta-analysis of randomized controlled trials

BACKGROUND

Vaccination and single-dose rifampin are the main proven effective intervention types for preventing leprosy among contacts of Mycobacterium leprae endemic areas. Currently, no high-quality evidence is available regarding the best prophylactic intervention.

OBJECTIVES

Our primary study aim is to detect the most effective prophylactic intervention for the prevention of leprosy.

METHODS

In May 2019, 12 databases were searched systematically. Updated search terms were developed in March 2020 to complete an updated search. All randomized controlled trials (RCTs) comparing the different types of chemoprophylactic and immunoprophylactic interventions in leprosy prevention were included. Our participants were contacts of patients with leprosy or people residing in leprosy endemic communities. We searched for different types of chemoprophylactic and immunoprophylactic interventions used in leprosy prevention. We used network meta-analysis and meta-analysis. Quality assessment was performed using Cochrane Risk of Bias for included RCTs, in which all included RCTs were rated to be low to moderate risk. We registered our protocol in Prospero with ID CRD42019143207.

RESULTS

Among 11 included studies (326 264 patients) from original and updated search terms, eight were eligible for network meta-analysis (NMA) while four were eligible for MA. Findings suggest that Bacillus Calmette-Guérin (BCG) vaccination was the most effective intervention compared to placebo (risk ratios (RRs) 0.49 (0.30, 0.80), p 0.77), followed by combined BCG vaccination and single-dose rifampicin (SDR) with similarly low values (RR 48%, p 0.77). BCG revaccination was the least effective intervention compared to placebo (RR 1.08 (0.36, 3.22), p 0.26).

CONCLUSION

Compared to placebo, the BCG vaccine was the most effective prophylactic intervention. The combination of BCG vaccination + SDR had nearly the same efficacy as BCG vaccination alone, while BCG revaccination was the least effective. Thus, vaccination proved to be a more effective treatment than SDR alone. A well-designed multicenter RCT is warranted to evaluate the safety of these vaccines.

A comprehensive research agenda for zero leprosy

BACKGROUND

Leprosy control achieved dramatic success in the 1980s-1990s with the implementation of short course multidrug therapy, which reduced the global prevalence of leprosy to less than 1 in 10 000 population. However, a period of relative stagnation in leprosy control followed this achievement, and only limited further declines in the global number of new cases reported have been achieved over the past decade.

MAIN TEXT

In 2016, major stakeholders called for the development of an innovative and comprehensive leprosy strategy aimed at reducing the incidence of leprosy, lowering the burden of disability and discrimination, and interrupting transmission. This led to the establishment of the Global Partnership for Zero Leprosy (GPZL) in 2018, with partners aligned around a shared Action Framework committed to achieving the WHO targets by 2030 through national leprosy program capacity-building, resource mobilisation and an enabling research agenda. GPZL convened over 140 experts from more than 20 countries to develop a research agenda to achieve zero leprosy. The result is a detailed research agenda focusing on diagnostics, mapping, digital technology and innovation, disability, epidemiological modelling and investment case, implementation research, stigma, post exposure prophylaxis and transmission, and vaccines. This research agenda is aligned with the research priorities identified by other stakeholders.

CONCLUSIONS

Developing and achieving consensus on the research agenda for zero leprosy is a significant step forward for the leprosy community. In a next step, research programmes must be developed, with individual components of the research agenda requiring distinct expertise, varying in resource needs, and operating over different timescales. Moving toward zero leprosy now requires partner alignment and new investments at all stages of the research process, from discovery to implementation.

The State of Affairs in Post-Exposure Leprosy Prevention: A Descriptive Meta-Analysis on Immuno- and Chemo-Prophylaxis

OBJECTIVE

Annually, over 200,000 people are diagnosed with leprosy, also called Hansen's disease. This number has been relatively stable over the past years. Progress has been made in the fields of chemoprophylaxis and immunoprophylaxis to prevent leprosy, with a primary focus on close contacts of patients. In this descriptive meta-analysis, we summarize the evidence and identify knowledge gaps regarding post-exposure prophylaxis against leprosy.

METHODS

A systematic literature search according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology was conducted by searching the medical scientific databases Cochrane, Embase, Pubmed/MEDLINE, Research Gate, Scopus and Web of Science on Jan. 22, 2020, using a combination of synonyms for index terms in four languages: "leprosy" and "population" or "contacts" and "prevention" or "prophylaxis." Subsequently, Infolep.org and Google Scholar were searched and the "snowball method" was used to retrieve other potentially relevant literature. The found articles were screened for eligibility using predetermined inclusion and exclusion criteria.

RESULTS

After deduplication, 1,515 articles were screened, and 125 articles were included in this descriptive meta-analysis. Immunoprophylaxis by bacillus Calmette-Guérin (BCG) vaccination is known to provide protection against leprosy. The protection it offers is higher in household contacts of leprosy patients compared with the general population and is seen to decline over time. Contact follow-up screening is important in the first period after BCG administration, as a substantial number of new leprosy patients presents three months post-vaccination. Evidence for the benefit of re-vaccination is conflicting. The World Health Organization (WHO) included BCG in its Guidelines for the Diagnosis, Treatment and Prevention of Leprosy by stating that BCG at birth should be maintained in at least all leprosy high-burden regions. Literature shows that several vaccination interventions with other immunoprophylactic agents demonstrate similar or slightly less efficacy in leprosy risk reduction compared with BCG. However, most of these studies do not exclusively focus on post-exposure prophylaxis. Two vaccines are considered future candidates for leprosy prophylaxis: Mycobacterium indicus pranii (MiP) and LepVax. For chemoprophylaxis, trials were performed with dapsone/acedapsone, rifampicin, and ROM, a combination of rifampicin, ofloxacin, and minocycline. Single-dose rifampicin is favored as post-exposure prophylaxis, abbreviated as SDR-PEP. It demonstrated a protective effect of 57% in the first two years after administration to contacts of leprosy patients. It is inexpensive, and adverse events are rare. The risk of SDR-PEP inducing rifampicin resistance is considered negligible, but continuous monitoring in accordance with WHO policies should be encouraged. The integration of contact screening and SDR-PEP administration into different leprosy control programs was found to be feasible and well accepted. Since 2018, SDR-PEP is included in the WHO Guidelines for the Diagnosis, Treatment and Prevention of Leprosy.

CONCLUSION

Progress has been made in the areas of chemoprophylaxis and immunoprophylaxis to prevent leprosy in contacts of patients. Investing in vaccine studies, like LepVax and MiP, and increasing harmonization between tuberculosis (TB) and leprosy research groups is important. SDR-PEP is promising as a chemoprophylactic agent, and further implementation should be promoted. More chemoprophylaxis research is needed on: enhanced medication regimens; interventions in varying (epidemiological) settings, including focal mass drug administration (fMDA); specific approaches per contact type; combinations with screening variations and field-friendly rapid tests, if available in the future; community and health staff education; ongoing antibiotic resistance surveillance; and administering chemoprophylaxis with SDR-PEP prior to BCG administration. Additionally, both leprosy prophylactic drug registration nationally and prophylactic drug availability globally at low or no cost are important for the implementation and further upscaling of preventive measures against leprosy, such as SDR-PEP and new vaccines.

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.

Correlates of GLA family adjuvants' activities

Lipopolysaccharide (LPS) is a well-defined agonist of Toll-like receptor (TLR) 4 that activates innate immune responses and influences the development of the adaptive response during infection with Gram-negative bacteria. Many years ago, Dr. Edgar Ribi separated the adjuvant activity of LPS from its toxic effects, an effort that led to the development of monophosphoryl lipid A (MPL). MPL, derived from Salmonella minnesota R595, has progressed through clinical development and is now used in various product-enabling formulations to support the generation of antigen-specific responses in several commercial and preclinical vaccines. We have generated several synthetic lipid A molecules, foremost glucopyranosyl lipid adjuvant (GLA) and second-generation lipid adjuvant (SLA), and have advanced these to clinical trial for various indications. In this review we summarize the potential and current positioning of TLR4-based adjuvant formulations in approved and emerging vaccines.

BCG and Adverse Events in the Context of Leprosy

Background

Notwithstanding its beneficial immunoprophylactic outcomes regarding leprosy and childhood TB, BCG vaccination may cause adverse events, particularly of the skin. However, this local hyper-immune reactivity cannot be predicted before vaccination, nor is its association with protection against leprosy known. In this study we investigated the occurrence of adverse events after BCG (re)vaccination in contacts of leprosy patients and analyzed whether the concomitant systemic anti-mycobacterial immunity was associated with these skin manifestations.

Methods

Within a randomized controlled BCG vaccination trial in Bangladesh, 14,828 contacts of newly diagnosed leprosy patients received BCG vaccination between 2012 and 2017 and were examined for adverse events 8 to 12 weeks post-vaccination. From a selection of vaccinated contacts, venous blood was obtained at follow-up examination and stimulated with Mycobacterium leprae (M. leprae) antigens in overnight whole-blood assays (WBA). M. leprae phenolic glycolipid-I-specific antibodies and 32 cytokines were determined in WBAs of 13 individuals with and 13 individuals without adverse events after vaccination.

Results

Out of the 14,828 contacts who received BCG vaccination, 50 (0.34%) presented with adverse events, mainly (80%) consisting of skin ulcers. Based on the presence of BCG scars, 30 of these contacts (60%) had received BCG in this study as a booster vaccination. Similar to the pathological T-cell immunity observed for tuberculoid leprosy patients, contacts with adverse events at the site of BCG vaccination showed elevated IFN-γ levels in response to M. leprae-specific proteins in WBA. However, decreased levels of sCD40L in serum and GRO (CXCL1) in response to M. leprae simultaneously indicated less T-cell regulation in these individuals, potentially causing uncontrolled T-cell immunity damaging the skin.

Conclusion

Skin complications after BCG vaccination present surrogate markers for protective immunity against leprosy, but also indicate a higher risk of developing tuberculoid leprosy.

Clinical Trial Registration

Netherlands Trial Register: NTR3087.

LepVax, a defined subunit vaccine that provides effective pre-exposure and post-exposure prophylaxis of M. leprae infection

Sustained elimination of leprosy as a global health concern likely requires a vaccine. The current standard, BCG, confers only partial protection and precipitates paucibacillary (PB) disease in some instances. When injected into mice with the T helper 1 (Th1)-biasing adjuvant formulation Glucopyranosyl Lipid Adjuvant in stable emulsion (GLA-SE), a cocktail of three prioritized antigens (ML2055, ML2380 and ML2028) reduced M. leprae infection levels. Recognition and protective efficacy of a single chimeric fusion protein incorporating these antigens, LEP-F1, was confirmed in similar experiments. The impact of post-exposure immunization was then assessed in nine-banded armadillos that demonstrate a functional recapitulation of leprosy. Armadillos were infected with M. leprae 1 month before the initiation of post-exposure prophylaxis. While BCG precipitated motor nerve conduction abnormalities more rapidly and severely than observed for control infected armadillos, motor nerve injury in armadillos treated three times, at monthly intervals with LepVax was appreciably delayed. Biopsy of cutaneous nerves indicated that epidermal nerve fiber density was not significantly altered in M. leprae-infected animals although Remak Schwann cells of the cutaneous nerves in the distal leg were denser in the infected armadillos. Importantly, LepVax immunization did not exacerbate cutaneous nerve involvement due to M. leprae infection, indicating its safe use. There was no intraneural inflammation but a reduction of intra axonal edema suggested that LepVax treatment might restore some early sensory axonal function. These data indicate that post-exposure prophylaxis with LepVax not only appears safe but, unlike BCG, alleviates and delays the neurologic disruptions caused by M. leprae infection.

A leprosy vaccine candidate has been developed that raises immune responses against targets gleaned from naturally resistant individuals. Researchers from the United States and Japan, led by Malcolm Duthie, of Seattle’s Infectious Disease Research Institute, tested a Mycobacterium leprae vaccine candidate that generated immune responses mimicking those found in partially-resistant patients, and immune co-inhabitants of the severely infected. The candidate, dubbed LepVax, inhibited infection in mice and, when administered post-infection, delayed and mitigated nerve damage in armadillos. This contrasts with the current vaccine, BCG, which can precipitate leprosy symptoms when given after infection. This study also revealed that M. leprae infection can induce ‘silent’ pre-clinical nerve aberations. High-risk populations may already be infected with M. leprae, making safe and effective post-exposure prophylaxis a landmark step in combating both the individual and global burden of leprosy.

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.

Mycobacterium bovis BCG and New Vaccines for the Prevention of Tuberculosis

Tuberculosis infects millions of people worldwide and remains a leading global killer despite widespread neonatal administration of the tuberculosis vaccine, bacillus Calmette-Guérin (BCG). BCG has clear and sustained efficacy, but after 10 years, its efficacy appears to wane, at least in some populations. Fortunately, there are many new tuberculosis vaccines in development today, some in advanced stages of clinical trial testing. Here we review the epidemiological need for tuberculosis vaccination, including evolving standards for administration to at risk individuals in developing countries. We also examine proven sources of immune protection from tuberculosis, which to date have exclusively involved natural or vaccine exposure to whole cell mycobacteria. After summarizing evidence for the use and efficacy of BCG, we detail the most promising new candidate vaccines against tuberculosis. The global need for a new tuberculosis vaccine is acute and huge, but clinical trials to be completed in the coming few years are likely either to identify a new tuberculosis vaccine or to substantially reframe how we understand immune protection from this historical scourge.

BCG and protection against inflammatory and auto-immune diseases

INTRODUCTION

Bacillus Calmette-Guérin (BCG) is the only available vaccine against tuberculosis. Although its protective efficacy against pulmonary tuberculosis is still under debate, it provides protection against other mycobacterial diseases. BCG is also an effective therapy against superficial bladder cancer and potentially decreases overall childhood mortality. Areas covered: The purpose of this paper is to provide a state-of-the-art summary of the beneficial effects of BCG in inflammatory and auto-immune diseases. As a strong inducer of Th1 type immunity, BCG has been reported to protect against atopic conditions, such as allergic asthma, a Th2-driven disorder. Its protective effect has been well documented in mice, but still awaits definitive evidence in humans. Similarly, murine studies have shown a protective effect of BCG against auto-immune diseases, such as multiple sclerosis and insulin-dependent diabetes, but studies in humans have come to conflicting conclusions. Expert commentary: Studies in mice have shown a beneficial effect of the BCG vaccine against allergic asthma, multiple sclerosis and diabetes. However, the understanding of its mechanism is still fragmentary and requires further in depth research. Some observational or intervention studies in humans have also suggested a beneficial effect, but definitive evidence for this requires confirmation in carefully conducted prospective studies.

Drug therapy of leprosy

Leprosy (Hansen’s disease) is a chronic granulomatous bacterial infection mainly affecting the skin and peripheral nervous system yet also involving other organs and systems as a result of a pathological process. The causative agent of leprosy - Mycobacterium leprae - is an obligate intracellular microorganism. Despite the removal of a threat of a leprosy epidemic, European countries still record outbreaks of the disease mainly among migrants coming from endemic areas. A golden standard of the treatment of leprosy is a WHO-recommended combined drug therapy comprising drugs such as dapsone, clofazimine and rifampicin. The article provides current data on the mechanisms of action, efficacy and safety of these drugs and their combined scheme of treatment obtained as a result of clinical trials. Moreover, it also reviews new regimens of the drug therapy of leprosy including those with the use of drugs from the group of fluoroquinols as well as immunotherapy of the disease.

Combination chemoprophylaxis and immunoprophylaxis in reducing the incidence of leprosy

Leprosy is a complex infectious disease caused by Mycobacterium leprae that is a leading cause of nontraumatic peripheral neuropathy. Current control strategies, with a goal of early diagnosis and treatment in the form of multidrug therapy, have maintained new case reports at ~225,000 per year. Diagnostic capabilities are limited and even with revisions to multidrug therapy regimen, treatment can still require up to a year of daily drug intake. Although alternate chemotherapies or adjunct immune therapies that could provide shorter or simpler treatment regimen appear possible, only a limited number of trials have been conducted. More proactive strategies appear necessary in the drive to elimination. As a prevention strategy, most chemoprophylaxis campaigns to date have provided about a 2-year protective window. Vaccination, in the form of a single bacillus Calmette–Guérin (BCG) immunization, generally provides ~50% reduction in leprosy cases. Adapting control strategies to provide both chemoprophylaxis and immunoprophylaxis has distinct appeal, with chemoprophylaxis theoretically buttressed by vaccination to generate immediate protection that can be sustained in the long term. We also discuss simple assays measuring biomarkers as surrogates for disease development or replacements for invasive, but not particularly sensitive, direct measures of M. leprae infection. Such assays could facilitate the clinical trials required to develop these new chemoprophylaxis, immunoprophylaxis strategies, and transition into wider use.

Leprosy among children under 15 years of age: literature review

Leprosy is a chronic infectious disease caused by Mycobacterium leprae, representing a public health issue in some countries. Though more prevalent in adults, the detection of new cases in children under 15 years of age reveals an active circulation of bacillus, continued transmission and lack of disease control by the health system, as well as aiding in the monitoring of the endemic. Among patients under 15 years of age, the most affected age group is children between 10 and 14 years of age, although cases of patients of younger than 1 year of age have also been reported. Household contacts are the primary source of infection, given that caretakers, such as babysitters and others, must be considered in this scenario. Paucibacillary forms of the disease prevailed, especially borderline-tuberculoid leprosy, with a single lesion in exposed areas of the body representing the main clinical manifestation. Reactional states: Lepra reactions are rare, although some authors have reported high frequencies of this phenomenon, the most frequent of which is Type 1 Lepra Reaction. Peripheral nerve involvement has been described at alarming rates in some studies, which increases the chance of deformities, a serious problem, especially if one considers the age of these patients. The protective effect of BCG vaccination was found in some studies, but no consensus has been reached among different authors. Children must receive the same multidrug therapy regimen and the doses should, ideally, be calculated based on the child´s weight. Adverse reactions to this therapy are rare within this age group. This article aims to review epidemiological, clinical, and therapeutic aspects of leprosy in patients under 15 years of age.

Causes of variation in BCG vaccine efficacy: examining evidence from the BCG REVAC cluster randomized trial to explore the masking and the blocking hypotheses

BCG protection varies and in some places (nearest the equator) is low or absent. Understanding this variation can inform the efforts to develop new vaccines against tuberculosis. Two main hypotheses are used to explain this variation: under masking, new vaccines are unlikely to increase protection; under blocking new vaccines have a greater potential to be effective when BCG is not. We conducted a cluster randomized trial to explored the masking and blocking hypotheses by studying BCG vaccine efficacy of neonatal vaccination and when administered for the first or a second (revaccination) time at school age in two sites (Manaus close and Salvador further south from the equator). Seven hundred and sixty three state schools were matched on socio economic characteristics of the neighborhood and 239,934 children were randomized to vaccine (BCG vaccination at school age) or control group. Protection by first BCG vaccination at school age was high in Salvador (34%, 95% CI 7-53%, p=0.017) but low in Manaus (8%, 95% CI t0 39-40%, p=0.686). For revaccination at school age, protection was modest in Salvador (19%, 95% CI 3-33%, p=0.022) and absent in Manaus (1%, 95% CI to 27-23%, p=0.932). Vaccine efficacy for neonatal vaccination was similar in Salvador (40%, 95% CI 22-54%, p<0.001) and Manaus (36%, 95% CI 11-53%, p=0.008). Variation in BCG efficacy was marked when vaccine was given at school age but absent at birth, which points towards blocking as the dominant mechanism. New tuberculosis vaccines that overcome or by pass this blocking effect could confer protection in situations where BCG is not protective.

The potential for vaccination in leprosy elimination: new tools for targeted interventions

Despite the huge effort and massive advances toward the elimination of leprosy over the last two decades, the disease has proven stubborn; new case detection rates have stabilised over the last few years and leprosy remains endemic in a number of localised regions. The American Leprosy Missions and Infectious Disease Research Institute have undertaken a large research effort aimed at developing new tools and a vaccine to continue the push for leprosy elimination. In this paper, we outline our strategy for the integration of rapid diagnostic tests and lab-based assays to facilitate the detection of early or asymptomatic leprosy cases, as well as the efficient and focused implementation of chemoprophylaxis and immunisation to intervene in leprosy development and transmission.

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

Inhibition of mycobacterial growth in vitro following primary but not secondary vaccination with Mycobacterium bovis BCG

Despite the widespread use of the Mycobacterium bovis BCG vaccine, there are more than 9 million new cases of tuberculosis (TB) every year, and there is an urgent need for better TB vaccines. TB vaccine candidates are selected for evaluation based in part on the detection of an antigen-specific gamma interferon (IFN-γ) response. The measurement of mycobacterial growth in blood specimens obtained from subjects immunized with investigational TB vaccines may be a better in vitro correlate of in vivo vaccine efficacy. We performed a clinical study with 30 United Kingdom adults who were followed for 6 months to evaluate the abilities of both a whole-blood- and a novel peripheral blood mononuclear cell (PBMC)-based mycobacterial growth inhibition assay to measure a response to primary vaccination and revaccination with BCG. Using cryopreserved PBMCs, we observed a significant improvement in mycobacterial growth inhibition following primary vaccination but no improvement in growth inhibition following revaccination with BCG (P < 0.05). Mycobacterial growth inhibition following primary BCG vaccination was not correlated with purified protein derivative (PPD) antigen-specific IFN-γ enzyme-linked immunospot (ELISPOT) responses. We demonstrate that a mycobacterial growth inhibition assay can detect improved capacity to control growth following primary immunization, but not revaccination, with BCG. This is the first study to demonstrate that an in vitro growth inhibition assay can identify a difference in vaccine responses by comparing both primary and secondary BCG vaccinations, suggesting that in vitro growth inhibition assays may serve as better surrogates of clinical efficacy than the assays currently used for the assessment of candidate TB vaccines.

Leprosy--evolution of the path to eradication

Leprosy is among the world's oldest and most dreaded diseases and it has been synonymous with stigma and discrimination due to the hideous deformities it produced, mystery around its aetiology and transmission and lack of any effective remedy till recently. Leprosy control started with the use of chaulmoogra oil and for the last three decades, multi drug therapy (MDT) has been our main tool against leprosy. In the last two decades, the reported global prevalence of active leprosy infection has dropped by almost 90 per cent by the combined efforts of the World Health Organization (WHO), local governments, health professionals, and non-governmental organizations (NGOs), however, a parallel drop in the incidence or new case detection rate (NCDR) has not occurred. From 1994 through 2011, more than 100,000 new cases are being detected annually, of whom maximum case load is from India. There is need for research on tools for early diagnosis, short and effective treatment, and prevention of deformities and disabilities. Evaluating the role of immunotherapy and immunoprophylaxis will also lead us to better understanding of their mode of action. Further molecular analysis of Mycobacterium leprae genome may provide the requisite basis for all this. The current reality is that there is a need to sustain and provide quality leprosy services to all persons through general health services, including good referral system. All these provisions in the integrated health care approach will go a long way in further reducing the stigma. Efforts need to be made to reduce deformity through early detection, self care, physiotherapy and reconstructive surgery and developing sound surveillance systems. With all the remarkable achievements in the fight against leprosy, the stage is now set for the final assault. It is hoped that with the efforts of all the stake holders and strong political will, the disease will be eradicated in the near future.

Leprous neuropathy

Leprous neuropathy, which is due to infection of nerve cells by Mycobacterium leprae, still affects millions of people in many developing countries. The clinical and pathological manifestations are determined by the natural resistance of the host to invasion of M. Leprae. Failure of early detection of leprosy often leads to severe disability in spite of eradication of mycobacterium at a later date. In the lepromatous type, bacilli are easily found in the skin and in nerve cells including Schwann cells, endothelial cells, and macrophages. In the tuberculoid type, a strong cell-mediated immune reaction leads to formation of granulomas and destruction of cells harboring bacilli and neighboring nerve fibers. In many cases, treatment of patients with the multibacillary leprosy is complicated by reversal reaction and further nerve damage. Nerve lesions lead to a symmetrical, pseudo-polyneuritic pattern in most cases of lepromatous leprosy, which is usually associated with typical skin lesions, but pure neuritic forms occur in up to 10% of patients with lepromatous leprosy. In the pure neuropathic cases, only nerve biopsy permits diagnosis. The multifocal pattern is more common in tuberculoid leprosy. Treatment is currently based on multidrug therapy with dapsone, rifampicin, and clofazimine. The use of corticosteroids can reduce or prevent nerve damage in reversal reactions. It is important to remember that sequelae, especially sensory loss, are extremely common, which can lead to secondary trophic changes due to repeated trauma in painless areas.

Evidence-based sample size estimation based upon an updated meta-regression analysis

A traditional meta-analysis examines the overall effectiveness of an intervention by producing a pooled estimate of treatment efficacy. In contrast to this, a meta-regression model seeks to determine whether a study-level covariate (X) is a plausible source of heterogeneity in a set of treatment effects. Upon performing such an analysis, the results may suggest the presence of a meaningful amount of variation in the treatment effects because of the covariate; however, the current set of trials may not provide sufficient statistical power for such a conclusion. The proposed approach provides quantitative insight into the amount of support that a new trial may provide to the hypothesis that X is a meaningful source of variation in an updated meta-regression model, which includes both the previously completed and the proposed trial. This empirical algorithm allows examination of the potential feasibility of a planned study of various sizes to further support or refute the hypothesis that X is a statistically significant source of variation. A detailed example illustrates the sample size estimation algorithm for both a planned individually or cluster randomized trial to investigate the now commonly accepted impact of geographical latitude on the observed effectiveness of the Bacillus Calmette-Guérin vaccine in the prevention of tuberculosis. Copyright © 2012 John Wiley & Sons, Ltd.

Advances and hurdles on the way toward a leprosy vaccine

Prevalence rates for leprosy have declined sharply over the past 20 y, with this decline generally attributed to the WHO multi-drug therapy (MDT) campaign to provide free-of-charge treatment to all diagnosed leprosy patients. The success of this program appears to have reached its nadir, however, as evidenced by the stalled decreases in both global prevalence and new case detection rates of leprosy. Mass BCG vaccination for the prevention of tuberculosis (TB) at national levels has had a positive effect on leprosy decline and is often overlooked as an important factor in current leprosy control programs. Because BCG provides incomplete protection against both TB and leprosy, newer more effective TB vaccines are being developed. The impact that application of these vaccines will have on current leprosy control programs is unclear. In this review, we assess the need for vaccines within leprosy control programs. We summarize and discuss leprosy vaccine strategies that have been deployed previously and discuss those strategies that are currently being developed to augment recent breakthroughs in leprosy control.

Leprosy

INTRODUCTION

The World Health Organization field leprosy classification is based on the number of skin lesions: paucibacillary leprosy (1-5 skin lesions), and multibacillary leprosy (more than 5 skin lesions). Worldwide, about 250,000 new cases of leprosy are reported each year, and about 2 million people have leprosy-related disabilities.

METHODS AND OUTCOMES

We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of interventions to prevent leprosy? What are the effects of treatments for leprosy? We searched: Medline, Embase, The Cochrane Library, and other important databases up to September 2009 (Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).

RESULTS

We found 20 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.

CONCLUSIONS

In this systematic review we present information relating to the effectiveness and safety of the following interventions: chemoprophylaxis with single-dose rifampicin, Bacillus Calmette-Guerin (BCG) plus killed Mycobacterium leprae vaccine, BCG vaccine, ICRC vaccine, multidrug treatment, multiple-dose treatment, Mycobacterium w vaccine, and single-dose treatment.

BCG vaccination and leprosy protection: review of current evidence and status of BCG in leprosy control

The bacillus Calmette-Guérin (BCG) vaccine, initially developed to provide protection against TB, also protects against leprosy; and the magnitude of this effect varies. Previous meta-analyses did not provide a summary estimate of the efficacy due to the heterogeneity of the results. We conducted a meta-analysis of published data including recently published studies (up to June 2009) to determine the efficacy of BCG protection on leprosy and to investigate whether age at vaccination, clinical form, number of doses, type of study, the latitude of study area and year of publication influence the degree of efficacy and explain the variation. In the light of the results, we argue for more emphasis on the role of BCG vaccination in leprosy control and research.

Vaccination with the ML0276 antigen reduces local inflammation but not bacterial burden during experimental Mycobacterium leprae infection

Leprosy elimination has been a goal of the WHO for the past 15 years. Widespread BCG vaccination and multidrug therapy have dramatically reduced worldwide leprosy prevalence, but new case detection rates have remained relatively constant. These data suggest that additional control strategies, such as a subunit vaccine, are required to block transmission and to improve leprosy control. We recently identified several Mycobacterium leprae antigens that stimulate gamma interferon (IFN-gamma) secretion upon incubation with blood from paucibacillary leprosy patients, a group who limit M. leprae growth and dissemination. In this study, we demonstrate that M. leprae-specific mouse T-cell lines recognize several of these antigens, with the ML0276 protein stimulating the most IFN-gamma secretion. We then examined if the ML0276 protein could be used in a subunit vaccine to provide protection against experimental M. leprae infection. Our data demonstrate that combining ML0276 with either a Toll-like receptor 4 (TLR4) (EM005), TLR7 (imiquimod), or TLR9 (CpG DNA) agonist during immunization induces Th1 responses that limit local inflammation upon experimental M. leprae infection. Our data indicate that only the ML0276/EM005 regimen is able to elicit a response that is transferable to recipient mice. Despite the potent Th1 response induced by this regimen, it could not provide protection in terms of limiting bacterial growth. We conclude that EM005 is the most potent adjuvant for stimulating a Th1 response and indicate that while a subunit vaccine containing the ML0276 protein may be useful for the prevention of immune pathology during leprosy, it will not control bacterial burden and is therefore unlikely to interrupt disease transmission.

Protective effect of the combination BCG vaccination and rifampicin prophylaxis in leprosy prevention

BCG vaccination and rifampicin chemoprophylaxis are both strategies for leprosy prevention. While the combined effect is unknown, the combination may give the desired push to halt leprosy transmission. Secondary analysis was done on results from a single centre, double blind, cluster randomized, and placebo-controlled trial. Individually, BCG (given at infancy) and rifampicin showed to protect against leprosy (57% [95% CI: 24-75%] and 58% [95% CI: 30-74%], respectively). The combined strategies showed a protective effect of 80% (95% CI: 50-92%). This is the first time that the additive effect of BCG and rifampicin are shown; the combined strategies can possibly lower leprosy incidence.