High anti-phenolic glycolipid-I IgM titers and hidden leprosy cases, Amazon region

Specialized active leprosy search strategies in an endemic area of the Brazilian Amazon identifies a hypermutated Mycobacterium leprae strain causing primary drug resistance

Introduction

Leprosy, an infectious disease caused by Mycobacterium leprae, remains a public health concern in endemic countries, particularly in Brazil. In this study, we conducted an active surveillance campaign in the hyperendemic city of Castanhal in the northeastern part of the state of Pará using clinical signs and symptoms combined with serological and molecular tools to diagnose new cases and to identify drug resistance of circulating M. leprae strains and their distribution in the community.

Methods

During an active surveillance of one week, we enrolled 318 individuals using three different strategies to enroll subjects for this study: (i) an active survey of previously treated cases from 2006 to 2016 found in the Brazil National Notifiable Disease Information System database (n = 23) and their healthy household contacts (HHC) (n = 57); (ii) an active survey of school children (SC) from two primary public schools in low-income neighborhoods (n = 178), followed by visits to the houses of these newly diagnosed SC (n = 7) to examine their HHC (n = 34) where we diagnosed additional new cases (n = 6); (iii) and those people who spontaneously presented themselves to our team or the local health center with clinical signs and/or symptoms of leprosy (n = 6) with subsequent follow-up of their HHC when the case was confirmed (n = 20) where we diagnosed two additional cases (n = 2). Individuals received a dermato-neurological examination, 5 ml of peripheral blood was collected to assess the anti-PGL-I titer by ELISA and intradermal earlobe skin scrapings were taken from HHC and cases for amplification of the M. leprae RLEP region by qPCR.

Results

Anti-PGL-I positivity was highest in the new leprosy case group (52%) followed by the treated group (40.9%), HHC (40%) and lowest in SC (24.6%). RLEP qPCR from SSS was performed on 124 individuals, 22 in treated cases, 24 in newly diagnosed leprosy cases, and 78 in HHC. We detected 29.0% (36/124) positivity overall in this sample set. The positivity in treated cases was 31.8% (7/22), while in newly diagnosed leprosy cases the number of positives were higher, 45.8% (11/23) and lower in HHC at 23.7% (18/76). Whole genome sequencing of M. leprae from biopsies of three infected individuals from one extended family revealed a hypermutated M. leprae strain in an unusual case of primary drug resistance while the other two strains were drug sensitive.

Discussion

This study represents the extent of leprosy in an active surveillance campaign during a single week in the city of Castanhal, a city that we have previously surveyed several times during the past ten years. Our results indicate the continuing high transmission of leprosy that includes fairly high rates of new cases detected in children indicating recent spread by multiple foci of infection in the community. An unusual case of a hypermutated M. leprae strain in a case of primary drug resistance was discovered. It also revealed a high hidden prevalence of overt disease and subclinical infection that remains a challenge for correct clinical diagnosis by signs and symptoms that may be aided using adjunct laboratory tests, such as RLEP qPCR and anti-PGL-I serology.

Leprosy among children in an area without primary health care coverage in Caratateua Island, Brazilian Amazon

Introduction

The detection of leprosy in children is an important epidemiological marker of the disease, indicating the community's early exposure to Mycobacterium leprae and active transmission of the infection.

Methods

In order to detect new cases among children by combining clinical evaluation and laboratory tests, we conducted an active case finding among individuals under 15 years old on Caratateua Island, located in the city of Belém, in the Pará state, an endemic region in the Amazon. Dermato-neurological examination, collection of 5 mL of peripheral blood for IgM anti-PGL-I antibody titration, and intradermal scraping for bacilloscopy and amplification of the specific RLEP region by qPCR were performed.

Results

Out of the 56 examined children, 28/56 (50%) new cases were identified. At the time of evaluation, 38/56 (67.8%) children presented one or more clinical alterations. Seropositivity was detected in 7/27 (25.9%) new cases and 5/24 (20.8%) undiagnosed children. DNA amplification of Mycobacterium leprae was observed in 23/28 (82.1%) of new cases and in 5/26 (19.2%) of non-cases. Out of the total cases, 11/28 (39.2%) were exclusively diagnosed by clinical evaluation performed during the active case finding. Seventeen new cases (60.8%) were detected considering the clinical alterations found in addition to positive results for qPCR. In this group, 3/17 (17.6%) qPCR-positive children presented significant clinical changes 5.5 months after the first evaluation.

Discussion

Our research detected a number of cases 5.6 times higher compared to the total number of pediatric cases recorded throughout the year 2021 in the municipality of Belém, which shows a critical scenario of underdiagnosing of leprosy among children under 15 years old in the region. We propose the use of qPCR technique to identify new cases among children with oligosymptomatic or early disease in endemic areas, in addition to the training of Primary Health Care professionals and the implementation of the Family Health Strategy coverage in the visited area.

NDO-BSA, LID-1, and NDO-LID Antibody Responses for Infection and RLEP by Quantitative PCR as a Confirmatory Test for Early Leprosy Diagnosis

Diagnostic tests for leprosy are limited, especially to identify early leprosy cases. We performed active case findings of leprosy to validate three potential antigen candidates and one molecular target. Cases were diagnosed by characteristic skin lesions, nerve enlargement, or skin sensation loss. Serum samples obtained from all subjects were tested by ELISA to assess antibody titers to three Mycobacterium leprae specific antigens: NDO-BSA, LID-1, and NDO-LID. Most of the field cases on Mosqueiro Island, northern Brazil, also collected slit skin smear for qPCR. Active case finding diagnosed 105 new cases of leprosy out of 894 subjects (11.7%), revealing a high prevalence of M. leprae in the region. With the use of amplification of the M. leprae-specific RLEP by qPCR, 68/79 (86.07%) of these cases were positive, confirming leprosy in subjects diagnosed in the field. Patients diagnosed at the leprosy reference center showed much higher antibody titers to all three antigens, while titers of patients from the field were significantly lower. Our results support previous findings that active surveillance by experienced leprologists can diagnose additional cases based on clinical findings, that many would not be identified using ELISA assay with the available biomarkers, and that RLEP qPCR may be used to confirm the majority of the field cases.

Forecasting the new case detection rate of leprosy in four states of Brazil: A comparison of modelling approaches

Background:

Brazil has the second highest annual number of new leprosy cases. The aim of this study is to formally compare predictions of future new case detection rate (NCDR) trends and the annual probability of NCDR falling below 10/100,000 of four different modelling approaches in four states of Brazil: Rio Grande do Norte, Amazonas, Ceará, Tocantins.

Methods:

A linear mixed model, a back-calculation approach, a deterministic compartmental model and an individual-based model were used. All models were fitted to leprosy data obtained from the Brazilian national database (SINAN). First, models were fitted to the data up to 2011, and predictions were made for NCDR for 2012–2014. Second, data up to 2014 were considered and forecasts of NCDR were generated for each year from 2015 to 2040. The resulting distributions of NCDR and the probability of NCDR being below 10/100,000 of the population for each year were then compared between approaches.

Results:

Each model performed well in model fitting and the short-term forecasting of future NCDR. Long-term forecasting of NCDR and the probability of NCDR falling below 10/100,000 differed between models. All agree that the trend of NCDR will continue to decrease in all states until 2040. Reaching a NCDR of less than 10/100,000 by 2020 was only likely in Rio Grande do Norte. Prediction until 2040 showed that the target was also achieved in Amazonas, while in Ceará and Tocantins the NCDR most likely remain (far) above 10/100,000.

Conclusions:

All models agree that, while incidence is likely to decline, achieving a NCDR below 10/100,000 by 2020 is unlikely in some states. Long-term prediction showed a downward trend with more variation between models, but highlights the need for further control measures to reduce the incidence of new infections if leprosy is to be eliminated.

Unexpectedly high leprosy seroprevalence detected using a random surveillance strategy in midwestern Brazil: A comparison of ELISA and a rapid diagnostic test

BACKGROUND

Leprosy diagnosis is mainly based on clinical evaluation, although this approach is difficult, especially for untrained physicians. We conducted a temporary campaign to detect previously unknown leprosy cases in midwestern Brazil and to compare the performance of different serological tests.

METHODS

A mobile clinic was stationed at the main bus terminal in Brasília, Brazil. Volunteers were quizzed and given a clinical exam to allow categorization as either patients, known contacts of patients or non-contacts, and blood was collected to determine anti-PGL-I and anti-LID-1 antibody titers by ELISA and by the NDO-LID rapid test. New cases of leprosy and the impact of performing this broad random surveillance strategy were evaluated. Accuracy values and concordance between the test results were evaluated among all groups.

RESULTS

Four hundred thirty-four individuals were evaluated, and 44 (10.1%) were diagnosed with leprosy. Borderline forms were the most frequent presentation. Both tests presented higher positivity in those individuals with multibacillary disease. Serological tests demonstrated specificities arround 70% for anti-PGL-1 and anti-LID ELISA; and arround 40% for NDO-LID. Sensitivities ranged from 48 to 62%. A substantial agreement between NDO-LID and ELISA with concomitant positive results was found within leprosy patients (Kappa index = 0.79 CI95% 0.36-1.22).

CONCLUSIONS

The unexpectedly high leprosy prevalence in this population indicates ongoing community-based exposure to Mycobacterium leprae antigens and high rates of subclinical infection. All tests showed low specificity and sensitivity values and therefore cannot be considered for use as stand-alone diagnostics. Rather, considering their positivity among MB patients and non-patients, these tests can be considered effective tools for screening and identifying individuals at high risk who might benefit from regular monitoring.

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.

Influence of Genetic Ancestry on INDEL Markers of NFKβ1, CASP8, PAR1, IL4 and CYP19A1 Genes in Leprosy Patients

BACKGROUND

Leprosy is an insidious infectious disease caused by the obligate intracellular bacteria Mycobacterium leprae, and host genetic factors can modulate the immune response and generate distinct categories of leprosy susceptibility that are also influenced by genetic ancestry.

METHODOLOGY/PRINCIPAL FINDINGS

We investigated the possible effects of CYP19A1 [rs11575899], NFKβ1 [rs28362491], IL1α [rs3783553], CASP8 [rs3834129], UGT1A1 [rs8175347], PAR1 [rs11267092], CYP2E1 [INDEL 96pb] and IL4 [rs79071878] genes in a group of 141 leprosy patients and 180 healthy individuals. The INDELs were typed by PCR Multiplex in ABI PRISM 3130 and analyzed with GeneMapper ID v3.2. The NFKβ1, CASP8, PAR1 and IL4 INDELs were associated with leprosy susceptibility, while NFKβ1, CASP8, PAR1 and CYP19A1 were associated with the MB (Multibacilary) clinical form of leprosy.

CONCLUSIONS/SIGNIFICANCE

NFKβ1 [rs28362491], CASP8 [rs3834129], PAR1 [rs11267092] and IL4 [rs79071878] genes are potential markers for susceptibility to leprosy development, while the INDELs in NFKβ1, CASP8, PAR1 and CYP19A1 (rs11575899) are potential markers for the severe clinical form MB. Moreover, all of these markers are influenced by genetic ancestry, and European contribution increases the risk to leprosy development, in other hand an increase in African contribution generates protection against leprosy.

Spatial analysis spotlighting early childhood leprosy transmission in a hyperendemic municipality of the Brazilian Amazon region

BACKGROUND

More than 200,000 new cases of leprosy were reported by 105 countries in 2011. The disease is a public health problem in Brazil, particularly within high-burden pockets in the Amazon region where leprosy is hyperendemic among children.

METHODOLOGY

We applied geographic information systems and spatial analysis to determine the spatio-temporal pattern of leprosy cases in a hyperendemic municipality of the Brazilian Amazon region (Castanhal). Moreover, we performed active surveillance to collect clinical, epidemiological and serological data of the household contacts of people affected by leprosy and school children in the general population. The occurrence of subclinical infection and overt disease among the evaluated individuals was correlated with the spatio-temporal pattern of leprosy.

PRINCIPAL FINDINGS

The pattern of leprosy cases showed significant spatio-temporal heterogeneity (p<0.01). Considering 499 mapped cases, we found spatial clusters of high and low detection rates and spatial autocorrelation of individual cases at fine spatio-temporal scales. The relative risk of contracting leprosy in one specific cluster with a high detection rate is almost four times the risk in the areas of low detection rate (RR = 3.86; 95% CI = 2.26-6.59; p<0.0001). Eight new cases were detected among 302 evaluated household contacts: two living in areas of clusters of high detection rate and six in hyperendemic census tracts. Of 188 examined students, 134 (71.3%) lived in hyperendemic areas, 120 (63.8%) were dwelling less than 100 meters of at least one reported leprosy case, 125 (66.5%) showed immunological evidence (positive anti-PGL-I IgM titer) of subclinical infection, and 9 (4.8%) were diagnosed with leprosy (8 within 200 meters of a case living in the same area).

CONCLUSIONS/SIGNIFICANCE

Spatial analysis provided a better understanding of the high rate of early childhood leprosy transmission in this region. These findings can be applied to guide leprosy control programs to target intervention to high risk areas.

High rates of undiagnosed leprosy and subclinical infection amongst school children in the Amazon Region

Leprosy in children is correlated with community-level factors, including the recent presence of disease and active foci of transmission in the community. We performed clinical and serological examinations of 1,592 randomly selected school children (SC) in a cross-sectional study of eight hyperendemic municipalities in the Brazilian Amazon Region. Sixty-three (4%) SC, with a mean age of 13.3 years (standard deviation = 2.6), were diagnosed with leprosy and 777 (48.8%) were seropositive for anti-phenolic glycolipid-I (PGL-I). Additionally, we evaluated 256 house-hold contacts (HHCs) of the students diagnosed with leprosy; 24 (9.4%) HHC were also diagnosed with leprosy and 107 (41.8%) were seropositive. The seroprevalence of anti-PGL-I was significantly higher amongst girls, students from urban areas and students from public schools (p < 0.0001). Forty-five (71.4%) new cases detected amongst SC were classified as paucibacillary and 59 (93.6%) patients did not demonstrate any degree of physical disability at diagnosis. The results of this study suggest that there is a high rate of undiagnosed leprosy and subclinical infection amongst children in the Amazon Region. The advantages of school surveys in hyperendemic areas include identifying leprosy patients at an early stage when they show no physical disabilities, preventing the spread of the infection in the community and breaking the chain of transmission.

Identification of serological biomarkers of infection, disease progression and treatment efficacy for leprosy

Although leprosy is curable with drug treatment, the identification of biomarkers of infection, disease progression and treatment efficacy would greatly help to reduce the overall prevalence of the disease. Reliable biomarkers would also reduce the incidence of grade-2 disability by ensuring that those who are most at risk are diagnosed and treated early or offered repeated treatments in the case of relapse. In this study, we examined the reactivity of sera from lepromatous and tuberculoid leprosy patients (LPs) against a panel of 12 recombinant Mycobacterium leprae proteins and found that six proteins were strongly recognised by multibacillary (MB) patients, while only three were consistently recognised by paucibacillary patients. To better understand the dynamics of patient antibody responses during and after drug therapy, we measured antibody titres to four recombinant proteins, phenolic glycolipid-I and lipoarabinomannan at baseline and up to two years after diagnosis to investigate the temporal changes in the antibody titres. Reactivity patterns to individual antigens and decreases in antibody titres were patient-specific. Antibody titres to proteins declined more rapidly vs. those to carbohydrate and glycolipid antigens. Compared to baseline values, increases in antibody titres were observed during reactional episodes in one individual. Additionally, antibody responses against a subset of antigens that provided a good prognostic indicator of disease progression were analysed in 51 household contacts of MB index cases for up to two years. Although the majority of these contacts showed no change or exhibited decreases in antibody titres, seven individuals developed higher titres towards one or more of these antigens and one individual with progressively higher titres was diagnosed with borderline lepromatous leprosy 19 months after enrolment. The results of this study indicate that antibody titres to specific M. leprae antigens can be used to monitor treatment efficacy in LPs and assess disease progression in those most at risk for developing this disease.