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

A recombinant chimeric antigen constructed with B-cell epitopes from Mycobacterium leprae hypothetical proteins is effective for the diagnosis of leprosy

The diagnosis if leprosy is difficult, as it requires clinical expertise and sensitive laboratory tests. In this study, we develop a serological test for leprosy by using bioinformatics tools to identify specific B-cell epitopes from Mycobacterium leprae hypothetical proteins, which were used to construct a recombinant chimeric protein, M1. The synthetic peptides were obtained and showed good reactivity to detect leprosy patients, although the M1 chimera have showed sensitivity (Se) and specificity (Sp) values higher than 90.0% to diagnose both paucibacillary (PB) and multibacillary (MB) leprosy patients, but not those developing tegumentary or visceral leishmaniasis, tuberculosis, Chagas disease, malaria, histoplasmosis and aspergillosis, in ELISA experiments. Using sera from household contacts, values for Se and Sp were 100% and 65.3%, respectively. In conclusion, our proof-of-concept study has generated data that suggest that a new recombinant protein could be developed into a diagnostic antigen for leprosy.

Epidemiological Characteristics and Factors Associated with Cure of Leprosy in Chongqing, China, from 1949 to 2019

Chongqing is one of the focuses of leprosy control in China. Although leprosy control in Chongqing has achieved remarkable results over the years, there are also some problems, such as recurrent epidemics and insufficient early detection in some areas. The aim of this study was to analyze the epidemiological characteristics of leprosy in Chongqing, from 1949 to 2019 and explore the potential factors sociated with cure of leprosy to provide a basis for improving leprosy prevention and treatment strategies in Chongqing. Epidemiological indicators such as incidence and prevalence rates were used to evaluate the prevalence of leprosy. The epidemiological characteristics and control situation of leprosy in patients were analyzed using demographic characteristics, diagnosis, and treatment. Survival analysis was conducted to explore factors associated with the cure of leprosy. From 1949 to 2019, 3,703 cases of leprosy were registered in Chongqing. The incidence of leprosy in the city peaked at 0.853/105 in 1960 and remained below 0.100/105 after 2003. The number of high incidence areas decreased significantly, but they were mainly concentrated in the northeast and southeast regions. The early detection rate increased yearly from 1949 to 2019, and the rate of grade 2 disability ranged from 38.2% to 21.7%, with a fluctuating downward trend after 1960. Male, young age, employment as a farmer, delayed diagnosis, and multibacillary leprosy were risk factors for leprosy cure. Chongqing should continue to strengthen leprosy monitoring to improve the early detection of leprosy and focus on sociated risk factors to carry out multiple strategies.

Spatio-temporal analysis of leprosy risks in a municipality in the state of Mato Grosso-Brazilian Amazon: results from the leprosy post-exposure prophylaxis program in Brazil

BACKGROUND

Leprosy post-exposure prophylaxis (LPEP) with single dose rifampicin (SDR) can be integrated into different leprosy control program set-ups once contact tracing has been established. We analyzed the spatio-temporal changes in the distribution of index cases (IC) and co-prevalent cases among contacts of leprosy patients (CP) over the course of the LPEP program in one of the four study areas in Brazil, namely the municipality of Alta Floresta, state of Mato Grosso, in the Brazilian Amazon basin.

METHODS

Leprosy cases were mapped, and socioeconomic indicators were evaluated to explain the leprosy distribution of all leprosy cases diagnosed in the period 2016-2018. Data were obtained on new leprosy cases [Notifiable diseases information system (Sinan)], contacts traced by the LPEP program, and socioeconomic variables [Brazilian Institute of Geography and Statistics (IBGE)]. Kernel, SCAN, factor analysis and spatial regression were applied to analyze changes.

RESULTS

Overall, the new case detection rate (NCDR) was 20/10 000 inhabitants or 304 new cases, of which 55 were CP cases among the 2076 examined contacts. Changes over time were observed in the geographic distribution of cases. The highest concentration of cases was observed in the northeast of the study area, including one significant cluster (Relative risk = 2.24; population 27 427, P-value < 0.001) in an area characterized by different indicators associated with poverty as identified through spatial regression (Coefficient 3.34, P-value = 0.01).

CONCLUSIONS

The disease distribution was partly explained by poverty indicators. LPEP influences the spatial dynamic of the disease and results highlighted the relevance of systematic contact surveillance for leprosy elimination.

Determining target populations for leprosy prophylactic interventions: a hotspot analysis in Indonesia

Background

Leprosy incidence remained at around 200,000 new cases globally for the last decade. Current strategies to reduce the number of new patients include early detection and providing post-exposure prophylaxis (PEP) to at-risk populations. Because leprosy is distributed unevenly, it is crucial to identify high-risk clusters of leprosy cases for targeting interventions. Geographic Information Systems (GIS) methodology can be used to optimize leprosy control activities by identifying clustering of leprosy cases and determining optimal target populations for PEP.

Methods

The geolocations of leprosy cases registered from 2014 to 2018 in Pasuruan and Pamekasan (Indonesia) were collected and tested for spatial autocorrelation with the Moran’s I statistic. We did a hotspot analysis using the Heatmap tool of QGIS to identify clusters of leprosy cases in both areas. Fifteen cluster settings were compared, varying the heatmap radius (i.e., 500 m, 1000 m, 1500 m, 2000 m, or 2500 m) and the density of clustering (low, moderate, and high). For each cluster setting, we calculated the number of cases in clusters, the size of the cluster (km²), and the total population targeted for PEP under various strategies.

Results

The distribution of cases was more focused in Pasuruan (Moran’s I = 0.44) than in Pamekasan (0.27). The proportion of total cases within identified clusters increased with heatmap radius and ranged from 3% to almost 100% in both areas. The proportion of the population in clusters targeted for PEP decreased with heatmap radius from > 100% to 5% in high and from 88 to 3% in moderate and low density clusters. We have developed an example of a practical guideline to determine optimal cluster settings based on a given PEP strategy, distribution of cases, resources available, and proportion of population targeted for PEP.

Conclusion

Policy and operational decisions related to leprosy control programs can be guided by a hotspot analysis which aid in identifying high-risk clusters and estimating the number of people targeted for prophylactic interventions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-022-07103-0.

Associations between occupation, leprosy disability and other sociodemographic factors in an endemic area of Brazil

BACKGROUND

In Brazil, new leprosy cases with grade-2 disability (G2D) have been increasing. Physical disability has been associated with experienced stigmatization, psychological distress, and social restriction.

OBJECTIVES

To identify factors associated with leprosy disability in an endemic area of Brazil focusing on occupational and other sociodemographic factors.

METHODS

Between July and December 2015, adult patients with multibacillary leprosy who attended a clinic in Belo Horizonte, Brazil were enrolled. Social, clinical, and demographic factors were collected from an administered questionnaire and medical charts. Occupations were categorized as manual vs non-manual. Descriptive statistics and multivariable logistic regression were performed to study associated factors with disability (Grade 1 disability (G1D) and G2D combined).

FINDINGS

Seventy-three patients were enrolled with 48 (65.8%) presenting with either G1D or G2D at the time of enrollment. Twenty-nine (39.7%) had G2D. About half of the patients (n = 36, 49%) reported a manual labor occupation and reactions were common (n = 53, 73%). On univariate analyses, older age (p = 0.048) and low education (p = 0.007) were associated with disability. On multivariable analyses, only low education (primary or less) was associated with disability (OR = 6.34, 95% CI 1.37, 29.26). Greater distance from clinic, income, smoking, marital status, and occupation were not associated.

MAIN CONCLUSIONS

Low education was associated with leprosy disability, consistent with prior studies, and therefore should be a focus for disability reduction programs. While the sample size of this study may have limited detection of associations between disability and social determinants tested, half of the patients reported a manual job, highlighting the need for more extensive studies on associations between occupation, disability, and related injuries.

High-risk transmission clusters of leprosy in an endemic area in the Northeastern Brazil: A retrospective spatiotemporal modelling (2001-2019)

OBJECTIVES

To analyse and map the leprosy risk areas in the state of Alagoas, an endemic region in the Northeastern Brazil, between 2001 and 2019.

METHODS

Ecological and time series study, using spatial analysis techniques. First, we analyse the epidemiological aspects of leprosy cases, using the data available in the Notifiable Diseases Information System; then, we used the segmented log-linear regression model to assess time trends. Spatial distribution was analysed by the Local Empirical Bayesian Estimator and by calculating the Global and Local Moran Index. Finally, spatiotemporal clusters were identified through scanning statistics, using the Kulldorf method of retrospective analysis.

RESULTS

We observed that Alagoas showed an average new case detection rate of 14.43/100,000 inhabitants between 2001 and 2019, being classified as highly endemic. The area of highest risk was the 9th health region (state hinterland), with increasing time trend (Annual Percentage Change/APC = 7.2; p-value < 0.05). Several clusters of high risk of leprosy transmission were verified in Alagoas, including the state capital and hinterland municipalities.

CONCLUSIONS

Our data indicate that active M. leprae transmission persists in Alagoas; that diagnosis is delayed and that there are high-risk areas, especially in inland municipalities.

Social inequalities and their association with the leprosy burden in a Brazilian city of low endemicity: An ecological study

OBJECTIVE

To analyse the association between social inequalities and the leprosy burden in a low endemicity scenario in the state of São Paulo, Brazil.

METHODS

This ecological study was carried out in the city of Ribeirão Preto, state of São Paulo, Brazil, considering leprosy cases notified from 2006 to 2016. Regarding social inequalities, dimensions related to high household density, literacy, home occupation conditions, health conditions, household income, ethnicity and age were considered. The generalised additive model for location, scale and shape (GAMLSS) was used to verify the association between the social inequalities and leprosy burden.

RESULTS

The increase in men and women with no education and people with an income of 1 to 2 minimum wages was associated with a relative increase in the number of leprosy cases (7.37%, 7.10% and 2.44%, respectively). Regarding the ethnicity variables, the increase in the proportion of men (black) and women (mixed race) with no schooling was associated with a relative increase in the number of cases of the disease (10.77% and 4.02%, respectively). Finally, for people of mixed race or ethnicity, the increase in the proportion of households with 1/2 to 1 minimum wage was related to a relative decrease in the total number of cases (-4.90%).

CONCLUSION

The results show that the determinants associated with the increase in leprosy cases are similar to those in Brazilian hyperendemic regions, and that even in cities with low endemicity, social inequality is one of the main determinants of the disease.

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

Background

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

Methods

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

Results

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

Conclusions

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

Supplementary Information

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

Towards the elimination of leprosy in Yunnan, China: A time-series analysis of surveillance data

Background

This study reviews the progress of leprosy elimination in Yunnan, China, over the past 30 years and identifies the challenges for the next stage of the program.

Methodology/Principal findings

Data were collected from the Leprosy Management Information System in China (LEPMIS). The progress made in the elimination of leprosy between 1990 and 2019 was measured. We defined two time periods, time period 1 (1990–2003) and time period 2 (2004–2019), because multidrug therapy (MDT) was launched for the treatment of leprosy in 1990 and a special fund from the central government was established for leprosy in 2004. During the past 30 years, the number of newly detected leprosy patients in Yunnan has steadily declined. In total, 703 newly detected leprosy patients were reported in 1990, and 353 and 136 cases were reported at the end of 2003 and 2019, respectively. At the end of 1990, 90.7% (117/129) of counties in Yunnan Province were identified as leprosy-endemic counties (>1 case per 100,000 population). By the end of 2003 and 2019, 39.3% (46/117) and 85.5% (100/117) of the leprosy-endemic counties, respectively, had dropped below the elimination threshold. The main challenges are the remaining leprosy-endemic counties, the high rate of cases with a contact history, insufficient early detection, and leprosy cases resulting in physical disability.

Conclusions/Significance

A multifaceted strategy for leprosy elimination in Yunnan Province has been successfully implemented, and remarkable progress has been made in the elimination of leprosy in this area. The priorities for leprosy elimination in the next stage are securing sustainable support and investment from the government, establishing an effective surveillance system, ensuring prompt early detection, providing treatment with MDT, preventing transmission of M. leprae, preventing disability, providing health education, and preventing recurrence of the epidemic situation of leprosy.

Compared to other provinces in China, Yunnan bears a significant burden of leprosy disease. Multidrug therapy (MDT) was launched for leprosy in 1990, and a special fund for leprosy was established in Yunnan Province by the central government in 2004. During the past 30 years, the number of newly detected leprosy patients has steadily declined, accompanied by an enormous decrease in the number of leprosy-endemic regions. Compared to the 1990–2003 period, the period after the establishment of the special fund from the central government (2004–2019) saw a decrease in the proportion of child cases and patients with grade 2 disability (G2D) and in the duration of delay in diagnosis among newly detected patients, while the proportion of patients with paucibacillary (PB) leprosy, the proportion belonging to minority groups, and the proportion of cases detected early increased significantly. The main challenges are the remaining leprosy-endemic counties, the high rate of cases with a contact history, insufficient early detection, and cases resulting in G2D. To eliminate leprosy in Yunnan Province, a multifaceted strategy should be implemented.

Insights into Mycobacterium leprae Proteomics and Biomarkers-An Overview

Although leprosy is curable, the identification of biomarkers for the early diagnosis of leprosy would play a pivotal role in reducing transmission and the overall prevalence of the disease. Leprosy-specific biomarkers for diagnosis, particularly for the paucibacillary disease, are not well defined. Therefore, the identification of new biomarkers for leprosy is one of the prime themes of leprosy research. Studying Mycobacterium leprae, the causative agent of leprosy, at the proteomic level may facilitate the identification, quantification, and characterization of proteins that could be potential diagnostics or targets for drugs and can help in better understanding the pathogenesis. This review aims to shed light on the knowledge gained to understand leprosy or its pathogen employing proteomics and its role in diagnosis.

Trends and forecasts of leprosy for a hyperendemic city from Brazil's northeast: Evidence from an eleven-year time-series analysis

This study’s objective was to estimate the temporal trends of leprosy according to sex and age groups, as well as to estimate and predict the progression of the disease in a hyperendemic city located in the northeast of Brazil. This ecological time-series study was conducted in Imperatriz, Maranhão, Brazil. Leprosy cases diagnosed between 2006 and 2016 were included. Detection rates stratified by sex and age groups were estimated. The study of temporal trends was accomplished using the Seasonal-Trend Decomposition method and temporal modeling of detection rates using linear seasonal autoregressive integrated moving average model according to Box and Jenkins method. Trend forecasts were performed for the 2017–2020 period. A total of 3,212 cases of leprosy were identified, the average incidence among men aged between 30 and 59 years old was 201.55/100,000 inhabitants and among women in the same age group was 135.28/100,000 inhabitants. Detection rates in total and by sex presented a downward trend, though rates stratified according to sex and age presented a growing trend among men aged less than 15 years old and among women aged 60 years old or over. The final models selected in the time-series analysis show the forecasts of total detection rates and rates for men and women presented a downward trend for the 2017–2020 period. Even though the forecasts show a downward trend in Imperatriz, the city is unlikely to meet a significant decrease of the disease burden by 2020.

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.

[Performance of leprosy case-contact surveillance: a space-time analysis in Bahia State, Northeast Brazil]

The aim was to analyze the space-time trend in the proportion of contacts examined among those recorded, according to demographic profile of new leprosy cases in the State of Bahia, Brazil, in the 2003-2014 cohort. This was a state population-based ecological study with temporal and spatial analyses of the proportion of contacts examined among those recorded, according to characteristics of the reference leprosy case, based on the Information System for Notifiable Diseases of the Brazilian Ministry of Health. The time trend analysis was based on Poisson regression (Joinpoints). Spatial analysis used spatial autocorrelation by local indicators of spatial association. Over the course of the historical series, 52.9% (55,116/104,142) of the recorded contacts were examined, with lower proportions in persons < 60 years of age, indigenous individuals, and residents of large cities (especially the state capital Salvador). There was an upward trend in the proportion of contacts examined, less evident when the reference leprosy case was a male, black, living in the rural area, and in small towns or the state capital. Spatial distribution showed that the majority of the municipalities showed precarious performance, with clusters identified in the North and Far South of the state. Bahia shows precarious performance on contact surveillance, particular in conditions of greater social vulnerability. Additional strategies should be implemented in order to overcome the operational obstacles to contact surveillance, considered essential for interrupting leprosy transmission in the state.

Hanseníase: incapacidades físicas e distribuição espacial em um município do Vale do Jequitinhonha/Minas Gerais

Introdução: A hanseníase no Brasil ainda é considerada como doença de saúde pública. É cada vez mais necessária a adoção de medidas profiláticas para o controle e prevenção da doença. A análise espacial tem se despontado como eficaz para estratégia de planejamento das ações. Objetivos: analisar as características epidemiológicas da hanseníase relacionadas à ocorrência de incapacidades físicas e descrever a distribuição espacial de casos novos de hanseníase no município de Diamantina-MG entre os anos de 2001 a 2014. Material e Métodos: Trata-se de um estudo epidemiológico, transversal, descritivo e analítico. Os dados clínicos e socioeconômicos foram coletados no Sistema de Informação de Agravos de Notificação. Os endereços foram georreferenciados através de técnicas de geoprocessamento, utilizando o software de acesso livre Qgis 2.18.0. Resultados: Foram diagnosticados 91 casos no período de estudo. As características que se associaram às incapacidades físicas foram: ser adulto (p=0,039), menos anos de estudo (p<0,001), forma clínica dimorfa (p<0,001) e modo de detecção passivo (p=0,024). Existe uma área de adoecimento na cidade. Conclusão: Sugere-se que existem dificuldades nos serviços de saúde para o controle e diagnóstico precoce da hanseníase. O estudo pode contribuir com gestores no planejamento das ações e com profissionais de saúde para busca ativa e diagnóstico precoce da hanseníase.

Monitoring and detection of leprosy patients in Southwest China: A retrospective study, 2010-2014

More than 100 counties, mainly in southwest China, report incidence rates of leprosy >1/100,000. The current study analysed the epidemiology of leprosy in southwest China to improve our understanding of the transmission pattern and improve control programs. 207 counties were selected in southwest China. Leprosy patients and their household contacts were recruited. The data from the medical interview and the serological antileprosy antibody of the leprosy patients were analysed. A total of 2,353 new cases of leprosy were interviewed. The distribution of leprosy patients was partly associated with local natural and economic conditions, especially several pocket areas. A total of 53 from 6643 household contacts developed leprosy, and the incidence rate of leprosy in the household contacts was 364/100,000 person-years. We found that NDO-BSA attained higher positive rates than MMP-II and LID-1 regardless of clinical types, disability and infection time in leprosy patients. By means of combination of antigens, 88.4% patients of multibacillary leprosy were detected, in contrast to 59.9% in paucibacillary leprosy. Household contacts should be given close attention for the early diagnosis, disruption of disease transmission and precise control. Applications of serology for multi-antigens were recommended for effective coverage and monitoring in leprosy control.

Social determinants, their relationship with leprosy risk and temporal trends in a tri-border region in Latin America

BACKGROUND

Brazil is the only country in Latin America that has adopted a national health system. This causes differences in access to health among Latin American countries and induces noticeable migration to Brazilian regions to seek healthcare. This phenomenon has led to difficulties in the control and elimination of diseases related to poverty, such as leprosy. The aim of this study was to evaluate social determinants and their relationship with the risk of leprosy, as well as to examine the temporal trend of its occurrence in a Brazilian municipality located on the tri-border area between Brazil, Paraguay and Argentina.

METHODS

This ecological study investigated newly-diagnosed cases of leprosy between 2003 and 2015. Exploratory analysis of the data was performed through descriptive statistics. For spatial analysis, geocoding of the data was performed using spatial scan statistic techniques to obtain the Relative Risk (RR) for each census tract, with their respective 95% confidence intervals calculated. The Bivariate Moran I test, Ordinary Least Squares (OLS) and Geographically Weighted Regression (GWR) models were applied to analyze the spatial relationships of social determinants and leprosy risk. The temporal trend of the annual coefficient of new cases was obtained through the Prais-Winsten regression. A standard error of 5% was considered statistically significant (p < 0.05).

RESULTS

Of the 840 new cases identified in the study, there was a predominance of females (n = 427, 50.8%), of white race/color (n = 685, 81.6%), age range 15 to 59 years (n = 624, 74.3%), and incomplete elementary education (n = 504, 60.0%). The results obtained from multivariate analysis revealed that the proportion of households with monthly nominal household income per capita greater than 1 minimum wage (β = 0.025, p = 0.036) and people of brown race (β = -0.101, p = 0.024) were statistically-significantly associated with risk of illness due to leprosy. These results also confirmed that social determinants and risk of leprosy were significantly spatially non-stationary. Regarding the temporal trend, a decrease of 4% (95% CI [-0.053, -0.033], p = 0.000) per year was observed in the rate of detection of new cases of leprosy.

CONCLUSION

The social determinants income and race/color were associated with the risk of leprosy. The study's highlighting of these social determinants can contribute to the development of public policies directed toward the elimination of leprosy in the border region.

Spatial distribution of leprosy in India: an ecological study

Background

As leprosy elimination becomes an increasingly realistic goal, it is essential to determine the factors that contribute to its persistence. We evaluate social and economic factors as predictors of leprosy annual new case detection rates within India, where the majority of leprosy cases occur.

Methods

We used correlation and linear mixed effect regressions to assess whether poverty, illiteracy, nighttime satellite radiance (an index of development), and other covariates can explain district-wise annual new case detection rate and Grade 2 disability diagnoses.

Results

We find only weak evidence of an association between poverty and annual new case detection rates at the district level, though illiteracy and satellite radiance are statistically significant predictors of leprosy at the district level. We find no evidence of rapid decline over the period 2008–2015 in either new case detection or new Grade 2 disability.

Conclusions

Our findings suggest a somewhat higher rate of leprosy detection, on average, in poorer districts; the overall effect is weak. The divide between leprosy case detection and true incidence of clinical leprosy complicates these results, particularly given that the detection rate is likely disproportionately lower in impoverished settings. Additional information is needed to distinguish the determinants of leprosy case detection and transmission during the elimination epoch.