Risk-benefit assessment of Bacillus Calmette-Guérin vaccination, anti-phenolic glycolipid I serology, and Mitsuda test response: 10-year follow-up of household contacts of leprosy patients

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

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

Can anti-PGL-I antibody isotypes differentiate leprosy contacts and leprosy patients?

BACKGROUND

Serological tests for antibody measurement in leprosy have a series of limitations in discriminating contacts and patients. The present paper intends to evaluate if association of more than one antibody isotype in serum samples may be a useful tool in leprosy diagnosis.

METHODS

This study evaluated 395 leprosy contacts and 71 leprosy index cases living in endemic municipalities in Northeastern Brazil. The participants were evaluated according to their anti-phenolic glycolipid antigen-I isotype (PGL-I) profile. Serum anti-PGL-I IgM, IgG, and IgA were measured by indirect ELISA.

RESULTS

A strong association was found for antibody positivity in MB leprosy index cases. The odds ratios were 6.11 (95% CI 3.08 - 12.16) for IgM, 3.31 (1.66 - 6.61) for IgG, and 16.97 (8.39 - 34.2) for IgA. For IgM associated with one or more isotypes, the OR was 21.0 (95% CI 10.11 - 43.64), and for IgG + IgA, the OR was 17.58 (6.23 - 49.54). The highest diagnostic sensitivity of 76.0% (95% CI 61.8 - 86.9) was observed for IgM, and the lowest value was 24.1% (13.0 - 38.2), which was observed for IgG + IgA isotypes. Regarding presumptive positive predictive values, the lowest value was obtained for IgM at 24.7% (95% CI 18.1 - 32.3), and the highest values were observed for IgM+ one or more isotypes and for IgG + IgA isotype at 60.0% (44.3 - 74.3) and 66.7% (41.0 - 86.7), respectively.

CONCLUSIONS

The present work demonstrated that by associating two or more positive antibody isotypes, the risk of facing a real case of leprosy may increase.

Design of a specific peptide against phenolic glycolipid-1 from Mycobacterium leprae and its implications in leprosy bacilli entry

BACKGROUND

Mycobacterium leprae, the causative agent of Hansen’s disease, causes neural damage through the specific interaction between the external phenolic glycolipid-1 (PGL-1) and laminin subunit alpha-2 (LAMA2) from Schwann cells.

OBJECTIVE

To design a LAMA2-based peptide that targets PGL-1 from M. leprae.

METHODS

We retrieved the protein sequence of human LAMA2 and designed a specific peptide using the Antimicrobial Peptide Database and physicochemical parameters for antimycobacterial peptide-lipid interactions. We used the AlphaFold2 server to predict its three-dimensional structure, AUTODOCK-VINA for docking, and GROMACS programs for molecular dynamics simulations.

FINDINGS

We analysed 52 candidate peptides from LAMA2, and subsequent screening resulted in a single 60-mer peptide. The mapped peptide comprises four β-sheets and a random coiled region. This peptide exhibits a 45% hydrophobic ratio, in which one-third covers the same surface. Molecular dynamics simulations show that our predicted peptide is stable in aqueous solution and remains stable upon interaction with PGL-1 binding. In addition, we found that PGL-1 has a preference for one of the two faces of the predicted peptide, which could act as the preferential binding site of PGL-1.

MAIN CONCLUSIONS

Our LAMA2-based peptide targeting PGL-1 might have the potential to specifically block this key molecule, suggesting that the preferential region of the peptide is involved in the initial contact during the attachment of leprosy bacilli to Schwann cells.

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

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

A 5-year evaluation of chemoprophylactic treatment in elementary school children with subclinical leprosy

Subclinical leprosy is an infectious disease in which the immune system remains infected with Mycobacterium leprae (M. leprae). The progress of subclinical leprosy to clinical cases within 1 year of infection is 1.5%, with an increase to 6% in the following 4 years. Rifampicin is frequently used for prevention of leprosy, and clarithromycin has a bactericidal effect on M. leprae. Thus, the combination of both is expected to improve disease control in patients with subclinical leprosy. The aim of the present study was to evaluate the efficacy of a chemoprophylactic treatment involving rifampicin and clarithromycin against subclinical leprosy in elementary school children from endemic areas of East Java over a 5-year period. The study was performed between 2011 and 2015. Samples were collected from 2,548 healthy elementary school children in Nguling (Pasuruan) and Raas (Sumenep), and analysed using ELISA for anti-PGL (phenolic glycolipid)-1 IgM antibodies. Children who were seropositive for anti-PGL-1 IgM antibodies received a chemoprophylactic regimen consisting of rifampicin (300 mg/day) and clarithromycin (250 mg/day) daily for the initial 10 days, followed by the same regimen every 2 weeks for 3 months. Clinical and serological evaluations were performed annually for 5 years. Amongst the 2,548 healthy elementary school children, 200 were seropositive. The anti-PGL-1 IgM antibody levels significantly decreased between 2011 and 2015 in Nguling (from 1,066.7 to 137.4 U/ml) and Raas (from 773.1 to 563.4 U/ml), the levels decreased every year. In addition, the proportion of patients with decreased anti-PGL-1 IgM antibody levels was consistently higher than patients with increased anti-PGL-1 IgM antibody levels in all periods, except during 2013-2014, in Nguling and Raas. Chemoprophylactic treatment involving rifampicin and clarithromycin may thus be effective against subclinical leprosy amongst elementary school children.

BCG and the risk of leprosy in Ciudad del Este, Paraguay, 2016-2017

OBJECTIVES

Paraguay has experienced a 35% reduction in the detected incidence of leprosy during the last ten years, as the vaccination coverage against tuberculosis (Bacillus of Calmette and Guérin [BCG] vaccine) reached ≥95% among infants. The objective of this case-control study was to evaluate the protective effect of BCG on the risk of leprosy.

METHODS

We used a population-based case-control study of 20 leprosy confirmed cases reported among residents of Ciudad del Este, Paraguay, diagnosed in 2016–2017. Three controls were selected from a random sample of households from the city. We assessed vaccine effectiveness using 1- odds ratio [OR], and confounding for age, gender, education, occupation, and marital status using stratified and exact logistic regression, and explored if there was effect modification calculating the synergy factor (SF) and relative excess risk due to interaction (RERI).

RESULTS

After controlling for age, gender, education, occupation and marital status, the OR of BCG scar on the risk of leprosy was 0.10 (95% confidence interval [CI], 0.02 to 0.45), for an estimate of vaccine effectiveness of 89.5% reduced risk of leprosy (95% CI, 55.2 to 98.1). There was evidence of heterogeneity by which the effectiveness of BCG seemed stronger among younger persons (Breslow-Day and Z-test of the SF had a p<0.05), and both the RERI and SF indicated a less then multiplicative and additive interaction of BCG and younger age.

CONCLUSIONS

BCG vaccination was associated with a decreased risk of leprosy in the study population, particularly in persons born after 1980.

Factors associated with the development of leprosy in contacts: a systematic review and meta-analysis

OBJECTIVE

To investigate the risk factors associated with leprosy in contacts of patients.

METHOD

We carried out a systematic review and meta-analysis by searching the databases MEDLINE, Embase, Cochrane Library, CINAHL, LILACS, Scopus, and Web of Science until September 2019. Four reviewers carried out the selection, analysis, and evaluation of quality of studies. The random effects model was used to calculate the pooled relative risk (RR) and 95% confidence intervals (95% CI) when heterogeneity was greater than 50%.

RESULTS

The search resulted in 2,148 references and included 24 reports. Most of the studies had been conducted in Brazil and India, had a cohort design and included household, neighbors, and social contacts. The risk factors associated with illness due to leprosy in contacts were: illiteracy (RR = 1,48; 95%CI 1,22 - 1,79), living in the same house (RR = 2,41; 95%CI 1,87 - 3,10) of a case of leprosy with high bacillary load (RR = 2.40; 95%CI 1.69 - 3.41), seropositivity to the Mycobacterium leprae PGL-1 (phenolic glycolipid-1) antigen (RR = 3.54; 95%CI 2.21 - 5.67), presence of the bacillus in the bloodstream (RR = 10.61; 95%CI 4.74 - 23.77) and negative Mitsuda reaction (RR = 2,68; 95%CI 1,76 - 4,07). Immunization with BCG (bacillus Calmette-Guérin) vaccine had a protective effect against leprosy.

CONCLUSION

Leprosy in contacts of patients involves social determination, individual susceptibility, and difficulties in access to disease control actions, but modifiable risk factors are the main determinants of illness in this population.

Leprosy incidence and risk estimates in a 33-year contact cohort of leprosy patients

Reduction in incidence has been associated with the introduction of novel approaches, like chemo/immune-prophylaxis. Incidence determined through follow-up cohort studies can evaluate the implementation of these innovative policies towards control and prevention. We have assessed the incidence in our contacts cohort over past 33 years, considering the effect of demographic and clinical variables. Survival analysis was used to estimate the risk of leprosy. A total of 9024 contacts were evaluated, of which 192 developed leprosy, resulting in an overall incidence of 1.4/1000 person-years. The multivariate analysis showed that the major risk factors were (i) contact from MB index cases and (ii) consanguinity (iii) intra household contact. Lower risk was detected for contacts with BCG scar who were revaccinated. There was a significant decrease in accumulated risk between the 2011-2019 period compared with 1987, probably linked to the improvement in laboratory tools to monitor contacts, thereby providing early diagnosis of contacts at intake and reduction of transmission. Our findings suggest that a combination of contact surveillance and tracing, adequate neurodermatological examination, and availability of molecular tools is highly effective in supporting early diagnosis, while a second dose of the BCG vaccination can exert extra protection.

Leprosy in a prison population: A new active search strategy and a prospective clinical analysis

BACKGROUND

This study evaluates an active search strategy for leprosy diagnosis based on responses to a Leprosy Suspicion Questionnaire (LSQ), and analyzing the clinical, immunoepidemiological and follow-up aspects for individuals living in a prison population.

METHODS

A cross-sectional study based on a questionnaire posing 14 questions about leprosy symptoms and signs that was distributed to 1,400 prisoners. This was followed by dermatoneurological examination, anti-PGL-I serology and RLEP-PCR. Those without leprosy were placed in the Non-leprosy Group (NLG, n = 1,216) and those diagnosed with clinical symptoms of leprosy were placed in the Leprosy Group (LG, n = 34).

FINDINGS

In total, 896 LSQ were returned (64%), and 187 (20.9%) of the responses were deemed as positive for signs/symptoms, answering 2.7 questions on average. Clinically, 1,250 (89.3%) of the prisoners were evaluated resulting in the diagnosis of 34 new cases (LG), based on well-accepted clinical signs and symptoms, a new case detection rate of 2.7% within this population, while the NLG were comprised of 1,216 individuals. The confinement time medians were 39 months in the LG while it was 36 months in the NLG (p>0.05). The 31 leprosy cases who responded to the questionnaire (LSQ+) had an average of 1.5 responses. The symptoms "anesthetized skin area" and "pain in nerves" were most commonly mentioned in the LG while "tingling, numbness in the hands/feet", "sensation of pricks and needles", "pain in nerves" and "spots on the skin" responses were found in more than 30% of questionnaires in the NLG. Clinically, 88.2% had dysesthetic macular skin lesions and 97.1% presented some peripheral nerve impairment, 71.9% with some degree of disability. All cases were multibacillary, confirming a late diagnosis. Anti-PGL-I results in the LG were higher than in the NLG (p<0.0001), while the RLEP-PCR was positive in 11.8% of the patients.

INTERPRETATION

Our findings within the penitentiary demonstrated a hidden prevalence of leprosy, although the individuals diagnosed were likely infected while living in their former communities and not as a result of exposure in the prison. The LSQ proved to be an important screening tool to help identify leprosy cases in prisons.

BCG Vaccination Status, Age, and Gender as Risk Factors for Leprosy in Endemic Areas in the Brazilian Amazon

In 2018, 208,619 new cases of leprosy were reported to the World Health Organization (WHO). Of these, 30,957 occurred in the Americas region and 28,660 (92.6% of the total in the Americas) were reported in Brazil. This study aimed to show the reality of the profile of a population in an endemic leprosy area in northern Brazil in relation to age, gender, and bacillus Calmette-Guérin (BCG) vaccination status through the collection of data in the field with the evaluation of the study individuals, who were recruited by spontaneous demand. A total of 405 individuals participated in the study, with 100 multibacillary, 57 paucibacillary, and 248 healthy contacts. A relationship was observed between the occurrence of the disease, as well as the multibacillary form with the largest age group. The male gender was associated with leprosy per se, with the multibacillary form and was the largest representative of the group that was not vaccinated once. BCG vaccination was effective both in protecting against leprosy per se and in the multibacillary form. These results are limited by sample size, may not be conclusive, and will need further confirmation in a larger cohort.

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

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

Importance of epidemiological surveillance of leprosy: analysis of the occurrence of leprosy in intra-domiciliary contacts in a capital in the Brazilian northeast region

INTRODUCTION

Intra-domiciliary contacts are a group with the highest risk of developing leprosy.

METHODS

A cross-sectional study of intra-domiciliary contacts of new leprosy cases was conducted. A descriptive analysis of the variables was performed.

RESULTS

Among 190 contacts, 63% were invited to visit the health unit, and 54.2% received the BCG vaccine. The prevalence of leprosy among the contacts was 4.7%.

CONCLUSIONS

The occurrence of leprosy among the contacts was high and similar to that found previously. There were failures in surveillance actions carried out by health units. Never-before treated cases were found.

BCG vaccine and leprosy household contacts: Protective effect and probability to becoming sick during follow-up

BACKGROUND

Immunoprophylaxis with Bacillus Calmette-Guérin (BCG) vaccine is still the most effective intervention in the prevention of leprosy among household contacts (HHCs) of leprosy patients.

METHODS

A retrospective cohort study using data of 5.061 HHCs for a period of 16 years (follow-up of 7 years per leprosy HHCs), evaluating the occurrence of disease as the main outcome and the presence or absence of BCG scars verified at the first evaluation. Statistical analyzes were performed using the relative risk, hazard ratio and survival curves by Kaplan-Meier test.

RESULTS

A total of 92 contacts sickened, of which 41.3% (38/92) in the first year and 58.7% (54/92) in the course of the other years of follow-up. Of those who became sick, 62% (57/92) developed borderline tuberculoid (BT). The additional protective effect occurred for those who had 2 BCG scars at the first follow-up assessment (Relative Risk: 0.41; p = 0.007) when compared to those not previously exposed to the vaccine. The number of BCG scars examined at the first assessment (t₀ = time zero) affected the occurrence of the outcome evidenced by the difference in survival curves throughout the follow-up (Log Rank, p = 0.041; Breslow, p = 0.012; Tarone-Ware, p = 0.020). Leprosy HHCs with 0 BCG scar at time zero (t₀) have a shorter survival time (average time of 22 months between t₀ and outcome) when compared to those with 2 BCG scars (average time of 36 months between t₀ and outcome).

CONCLUSIONS

Vaccination of healthy individuals without signs and symptoms of leprosy is extremely important because BCG vaccine has an additional protective effect in those cases with 2 BCG scars throughout follow-up. Reducing the risk of leprosy HHCs becoming sick depends on preventive actions such as immunoprophylaxis and index cases treatment.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

Background

Household contacts constitute the highest risk group for leprosy development, and despite significant progress in the disease control, early diagnosis remains the primary goals for leprosy management programs.

Methods

We have recruited 175 seropositive and 35 seronegative household contacts from 2014 to 2016, who were subjected to an extensive protocol that included clinical, molecular (peripheral blood qPCR, slit-skin smear qPCR, skin biopsy qPCR) and electroneuromyographic evaluations.

Results/Principal findings

The positivity of peripheral blood qPCR of seropositive contacts was 40.6% (71/175) whereas only 8.6% (3/35) were qPCR positive in seronegative contacts (p = 0.0003). For the slit-skin smear, only 4% (7/175) of seropositive contacts presented positive bacilloscopy, whereas the qPCR detected 47.4% (83/175) positivity in this group compared with only 17.1% (6/35) in seronegative contacts (p = 0.0009). In the ENMG evaluation of contacts, 31.4% (55/175) of seropositives presented some neural impairment, and 13.3% (4/35) in seronegatives (p = 0.0163). The presence of neural thickening conferred a 2.94-fold higher chance of ENMG abnormality (p = 0.0031). Seropositive contacts presented a 4.04-fold higher chance of neural impairment (p = 0.0206). The peripheral blood qPCR positivity presented odds 2.08-fold higher towards neural impairment (OR, 2.08; p = 0.028). Contrarily, the presence of at least one BCG vaccine scar demonstrated 2.44-fold greater protection against neural impairment (OR = 0.41; p = 0.044).

Conclusions/Significance

ELISA anti-PGL-I is the most important test in determining the increased chance of neural impairment in asymptomatic leprosy household contacts. The combination of the two assays (ELISA anti-PGL-I and peripheral blood qPCR) and the presence of BCG scar may identify individuals with higher chances of developing leprosy neuropathy, corroborating with the early diagnosis and treatment.

Despite the apparent progress observed in recent years in leprosy control, early identification of cases remains one of the primary objectives of control programs. In addition, the failure of the current therapeutic scheme on the incidence of leprosy demonstrates that the disease elimination as a public health program promoted by the World Health Organization (WHO) depends on an incisive action to interrupt its transmission chain. The long incubation period of leprosy, its insidious symptoms and signs may difficult its diagnosis. Several studies have recently demonstrated that IgM anti-PGL-I seropositive contacts present higher chances to become ill than seronegative ones. Therefore, our question was: do seropositive contacts at greater risk of becoming sick already present subclinical neural damage? Therefore, our approach was to analyse anti-PGL-I seropositive contacts through electroneuromyography. The development and implementation of more specific and sensitive methods for the detection of M. leprae and its neural impairment, using immunological, molecular and neurophysiological tools are mandatory to increase the knowledge of leprosy epidemiology, to break its chain of transmission, thereby enabling effective control of this disease. This report demonstrated that seropositive contacts is the population group with higher chances of neural impairment.

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.

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.

Risk ratios for contagious outcomes

Epidemiologists commonly use the risk ratio to summarize the relationship between a binary covariate and outcome, even when outcomes may be dependent. Investigations of transmissible diseases in clusters-households, villages or small groups-often report risk ratios. Epidemiologists have warned that risk ratios may be misleading when outcomes are contagious, but the nature of this error is poorly understood. In this study, we assess the meaning of the risk ratio when outcomes are contagious. We provide a mathematical definition of infectious disease transmission within clusters, based on the canonical stochastic susceptible-infective model. From this characterization, we define the individual-level ratio of instantaneous infection risks as the inferential target, and evaluate the properties of the risk ratio as an approximation of this quantity. We exhibit analytically and by simulation the circumstances under which the risk ratio implies an effect whose direction is opposite that of the true effect of the covariate. In particular, the risk ratio can be greater than one even when the covariate reduces both individual-level susceptibility to infection, and transmissibility once infected. We explain these findings in the epidemiologic language of confounding and Simpson's paradox, underscoring the pitfalls of failing to account for transmission when outcomes are contagious.

Revisiting primary neural leprosy: Clinical, serological, molecular, and neurophysiological aspects

BACKGROUND

Leprosy neuropathy is considered the most common peripheral neuropathy of infectious etiology worldwide, representing a public health problem. Clinical diagnosis of primary neural leprosy (PNL) is challenging, since no skin lesions are found and the slit skin smear bacilloscopy is negative. However, there are still controversial concepts regarding the primary-neural versus pure-neural leprosy definition, which will be explored by using multiple clinical-laboratory analyses in this study.

METHODOLOGY/PRINCIPAL FINDINGS

Seventy patients diagnosed with primary neural leprosy from 2014 to 2016 underwent clinical, laboratorial and neurophysiological evaluation. All patients presented an asymmetric neural impairment, with nerve thickening in 58.6%. Electroneuromyography showed a pattern of mononeuropathy in 51.4%. Positivity for ELISA anti-PGL1 was 52.9%, while the qPCR of slit skin smear was 78.6%. The qPCR of nerve biopsies was positive in 60.8%. Patients with multiple mononeuropathy patterns showed lower levels of anti-PGL-1 (p = 0.0006), and higher frequency of neural thickening (p = 0.0008) and sensory symptoms (p = 0.01) than those with mononeuropathy.

CONCLUSIONS/SIGNIFICANCE

PNL is not a synonym of pure neural leprosy, as this condition may include a generalized immune response and also a skin involvement, documented by molecular findings. Immunological, molecular, and neurophysiological tools must be implemented for diagnosing primary neural leprosy to achieve effective treatment and reduction of its resultant disabilities that still represent a public health problem in several developing nations. Finally, we propose a algorithm and recommendations for the diagnosis of primary neural leprosy based on the combination of the three clinical-laboratorial tools.

Nerve Damage in Young Patients with Leprosy Diagnosed in an Endemic Area of the Brazilian Amazon: A Cross-Sectional Study

OBJECTIVE

To describe nerve damage and its association with clinical and epidemiologic characteristics in young patients with leprosy diagnosed in an endemic area of the Brazilian Amazon.

STUDY DESIGN

All 45 patients with leprosy younger than 15 years of age and diagnosed at a health referral unit in northern Brazil were invited to participate in a cross-sectional, descriptive, analytical study. Subjects were submitted to a templated simple neurologic examination of the peripheral nerves and answered a structured questionnaire.

RESULTS

Of 41 cases, referral was the mode of detection in 33 participants (80.5%); 19 (46.3%) had been seen by 3 or more physicians to obtain a diagnosis, and 26 (63.4%) had received other diagnoses. The interval between the onset of symptoms and diagnosis was more than 1 year in 30 cases (73.2%). Borderline leprosy was the predominant clinical form (48.8%); 63.4% of the participants had multibacillary leprosy, 31.7% had nerve damage, and 17.1% exhibited disabilities. The following variables showed a statistically significant association (P???.05) with nerve damage at diagnosis: home visit by the community health worker, number of doctors seen, number of skin lesions (>5), and lesions along the path of nerve trunks.

CONCLUSION

Centralized healthcare, a low frequency of home visits by community health workers, and the difficulty in diagnosing leprosy in children are factors that contribute to late treatment initiation and an increased risk of peripheral nerve damage. In addition, multiple skin lesions and lesions along the path of nerve trunks require rigorous monitoring.

Spatial and temporal epidemiology of Mycobacterium leprae infection among leprosy patients and household contacts of an endemic region in Southeast Brazil

BACKGROUND

Leprosy is a chronic infectious disease that remains a public health problem in low- and middle-income countries. Household contacts of leprosy patients (HHCs) have increased risk of developing disease and are important links in the chain of transmission of Mycobacterium leprae. Based on epidemiological and operational factors, the global elimination strategy depends on the geographic stratification of endemic areas to intensify control activities. The purpose of the study was to integrate epidemiological indicators and serology into the spatial and temporal analysis of M. leprae infection, in order to understanding of the dynamics of transmission, essential information for the control of leprosy.

METHODOLOGY

Using location-based technologies and epidemiological data obtained from leprosy cases (N=371) and HHCs (N=53), during a 11year period (2004-2014), we explored the spatial and temporal distribution of diagnosed cases: stratified according their disease manifestation; and of subclinical infection among HHCs: determined by serology (anti-PGL-I ELISA and anti-NDO-LID rapid lateral-flow test); in order to assess the distribution pattern of the disease and the areas of greatest risk of illness, in a highly endemic municipality (Ituiutaba, MG) in the southeast region of Brazil.

RESULTS

Seropositivity among HHCs was: 17% (9/53) for anti-PGL-I ELISA; and 42% for the NDO-LID rapid lateral-flow test. Forty-nine percent of the contacts were seropositive to at least one of the immunological tests.

DISCUSSION

We observed substantial spatial heterogeneity of cases throughout the urban perimeter. Even so, four main clusters of patients and three main clusters of subclinical infection were identified.

CONCLUSIONS

Spatio-temporal epidemiology associated to serological assessment can identify high-risk areas imbedded within the overall epidemic municipality, to prioritize active search of new cases as well support prevention strategies in these locations of greater disease burden and transmission. Such techniques should become increasingly useful and important in future action planning of health interventions, as decisions must be made to effectively allocate limited resources.

Molecular Evidence for the Aerial Route of Infection of Mycobacterium leprae and the Role of Asymptomatic Carriers in the Persistence of Leprosy

BACKGROUND

 Leprosy persists as a public health problem. The chain of transmission and mechanism of infection are not completely understood. In the current study, we investigated the route of infection and of disease onset, from airway exposure, colonization, and bloodstream dissemination.

METHODS

 Mycobacterium leprae DNA was detected through quantitative polymerase chain reaction in nasal vestibule, nasal turbinate mucosa, and peripheral blood samples, along with anti-phenolic glycolipid I serology and skin tests from the same individual, from 113 leprosy patients and 104 household contacts of patients (HHCs). Bivariate statistics and multiple correspondence analysis were employed.

RESULTS

 The rates of DNA positivity among patients were 66.4% (75 of 113) for nasal swab samples, 71.7% (81 of 113) for nasal turbinate biopsy samples, 19.5% (22 of 113) for blood samples, with seropositivity of 62.8% (71 of 113 samples) and with increasing incidences toward the multibacillary pole of the clinical spectrum. Positivity among HHCs were as follows: 49% (51 of 104) for nasal swab samples, 53.8% (56 of 104) for nasal biopsy samples, 6.7% (7 of 104) for blood samples, and 18.3% (19 of 104 samples) for anti-phenolic glycolipid I serology. During the follow-up of 5-7 years, out of 104 HHCs, 7 developed leprosy (6.7%). Risk for the disease outcome was estimated by comparing results in HHCs who develop leprosy with those not affected. Neither nasal passage nor mucosa positivity was determinant of later disease onset; however, blood presence increased the risk for disease development (relative risk/positive likelihood ratio, 5.54; 95% confidence interval, 1.30-23.62), as did seropositivity (positive likelihood ratio, 3.69 [1.67-8.16]; relative risk, 5.97 [1.45-24.5]).

CONCLUSIONS

 Our findings strongly suggest that the aerosol route of infection and transmission is predominant and that HHCs contribute to the infection risk to themselves and probably to others.