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Sinha S, Haq MA, Ahmad R, Banik S, Kumar S, Haque M. Unmasking the Hidden Burden: A Delayed Diagnosis of Leprosy Patients With Grade 2 Disability and Its Effects on the Healthcare System in Bangladesh. Cureus 2024; 16:e58708. [PMID: 38651088 PMCID: PMC11033826 DOI: 10.7759/cureus.58708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/22/2024] [Indexed: 04/25/2024] Open
Abstract
Introduction Leprosy remains a significant cause of preventable disability worldwide. Early diagnosis and treatment of leprosy are critical not only to stop its spread but also to prevent physical and social complications and reduce the disease burden. Objectives The study aims to evaluate the factors that lead to a delayed leprosy diagnosis. Methods This study was conducted in the outpatient departments of Leprosy Control Institute and Hospital, Dhaka, Bangladesh, and at Medical College for Women and Hospital, Dhaka, Bangladesh, from March 2023 to June 2023. A total number of 252 male (148) and female (104) patients were selected with any sign of leprosy, including disability, age ranging from 15 to 74 years. Data was collected in a pre-designed structured questionnaire by the researchers. To assess the risk of independent exposures of Grade 2 leprosy disabilities, we used a logistic regression model. A chi-square test showed the association between significant effects and leprosy disabilities. A p-value of 0.05 was considered as significant. For statistical analysis, STATA version 15 (StataCorp LLC, College Station, Texas, USA) was used. Results The study participants exhibited a higher percentage of disability, with a rate of 25.8% for Grade 2 disabilities. In addition to this, males represented a more considerable proportion, 58.7%, than females among leprosy and disability patients across all levels of disability. In our study, lack of money and painless symptoms showed a significant association (p<0.001) with Grade 2 disability. Conclusion The study reveals that Grade 2 disabilities are more common in males and are particularly prevalent in lower socioeconomic groups.
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Affiliation(s)
- Susmita Sinha
- Physiology, Khulna City Medical College and Hospital, Khulna, BGD
| | | | - Rahnuma Ahmad
- Physiology, Medical College for Women and Hospital, Dhaka, BGD
| | - Suman Banik
- Administration, Directorate General of Health Services (DGHS), Dhaka, BGD
| | - Santosh Kumar
- Periodontology and Implantology, Karnavati School of Dentistry, Karnavati University, Gandhinagar, IND
| | - Mainul Haque
- Therapeutics, Karnavati Scientific Research Center (KSRC), School of Dentistry, Karnavati University, Gandhinagar, IND
- Pharmacology and Therapeutics, National Defence University of Malaysia, Kuala Lumpur, MYS
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Taal AT, Garg A, Lisam S, Agarwal A, Barreto JG, van Brakel WH, Richardus JH, Blok DJ. Identifying clusters of leprosy patients in India: A comparison of methods. PLoS Negl Trop Dis 2022; 16:e0010972. [PMID: 36525390 PMCID: PMC9757546 DOI: 10.1371/journal.pntd.0010972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2022] [Accepted: 11/22/2022] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Preventive interventions with post-exposure prophylaxis (PEP) are needed in leprosy high-endemic areas to interrupt the transmission of Mycobacterium leprae. Program managers intend to use Geographic Information Systems (GIS) to target preventive interventions considering efficient use of public health resources. Statistical GIS analyses are commonly used to identify clusters of disease without accounting for the local context. Therefore, we propose a contextualized spatial approach that includes expert consultation to identify clusters and compare it with a standard statistical approach. METHODOLOGY/PRINCIPAL FINDINGS We included all leprosy patients registered from 2014 to 2020 at the Health Centers in Fatehpur and Chandauli districts, Uttar Pradesh State, India (n = 3,855). Our contextualized spatial approach included expert consultation determining criteria and definition for the identification of clusters using Density Based Spatial Clustering Algorithm with Noise, followed by creating cluster maps considering natural boundaries and the local context. We compared this approach with the commonly used Anselin Local Moran's I statistic to identify high-risk villages. In the contextualized approach, 374 clusters were identified in Chandauli and 512 in Fatehpur. In total, 75% and 57% of all cases were captured by the identified clusters in Chandauli and Fatehpur, respectively. If 100 individuals per case were targeted for PEP, 33% and 11% of the total cluster population would receive PEP, respectively. In the statistical approach, more clusters in Chandauli and fewer clusters in Fatehpur (508 and 193) and lower proportions of cases in clusters (66% and 43%) were identified, and lower proportions of population targeted for PEP was calculated compared to the contextualized approach (11% and 11%). CONCLUSION A contextualized spatial approach could identify clusters in high-endemic districts more precisely than a standard statistical approach. Therefore, it can be a useful alternative to detect preventive intervention targets in high-endemic areas.
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Affiliation(s)
- Anneke T. Taal
- NLR, Amsterdam, The Netherlands
- Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
- * E-mail:
| | | | | | | | | | | | | | - David J. Blok
- Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
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Bulstra CA, Blok DJ, Alam K, Butlin CR, Roy JC, Bowers B, Nicholls P, de Vlas SJ, Richardus JH. Geospatial epidemiology of leprosy in northwest Bangladesh: a 20-year retrospective observational study. Infect Dis Poverty 2021; 10:36. [PMID: 33752751 PMCID: PMC7986508 DOI: 10.1186/s40249-021-00817-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Accepted: 03/05/2021] [Indexed: 11/21/2022] Open
Abstract
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.
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Affiliation(s)
- Caroline A Bulstra
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands. .,Heidelberg Institute of Global Health, Heidelberg University Hospital, Heidelberg, Germany.
| | - David J Blok
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Khorshed Alam
- Rural Health Programme, The Leprosy Mission International Bangladesh, Nilphamari, Bangladesh
| | - C Ruth Butlin
- The Leprosy Mission England and Wales, Goldhay Way, Orton Goldhay, Peterborough, England
| | - Johan Chandra Roy
- Rural Health Programme, The Leprosy Mission International Bangladesh, Nilphamari, Bangladesh
| | - Bob Bowers
- Menzies Health Institute Queensland, Griffith University, Brisbane, Australia
| | | | - Sake J de Vlas
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Jan Hendrik Richardus
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
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Ramos ACV, Santos Neto M, Arroyo LH, Yamamura M, Assis IS, Alves JD, Arcoverde MAM, Alves LS, Berra TZ, Martoreli Júnior JF, Pieri FM, Arcêncio RA. Magnitude of social determinants in high risk areas of leprosy in a hyperendemic city of northeastern Brazil: An ecological study. LEPROSY REV 2020. [DOI: 10.47276/lr.91.1.41] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Nery JS, Ramond A, Pescarini JM, Alves A, Strina A, Ichihara MY, Fernandes Penna ML, Smeeth L, Rodrigues LC, Barreto ML, Brickley EB, Penna GO. Socioeconomic determinants of leprosy new case detection in the 100 Million Brazilian Cohort: a population-based linkage study. Lancet Glob Health 2019; 7:e1226-e1236. [PMID: 31331811 PMCID: PMC6688099 DOI: 10.1016/s2214-109x(19)30260-8] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 05/17/2019] [Accepted: 05/17/2019] [Indexed: 12/24/2022]
Abstract
BACKGROUND Although leprosy is recognised as a disease of poverty, there is little evidence on the specific socioeconomic factors associated with disease risk. To inform targeted strategies for disease elimination, we investigated socioeconomic markers of leprosy risk in Brazil. METHODS Socioeconomic data from the 100 Million Brazilian Cohort were linked to the Brazilian national disease registry (Sistema de Informação de Agravos de Notificação) for leprosy from Jan 1, 2007, to Dec 31, 2014. Using Poisson regression, we assessed the association of socioeconomic factors with risk of incident leprosy in the full cohort and in children (aged 0-15 years), by leprosy subtype and region of residence. FINDINGS In an analysis of 23 899 942 individuals including 18 518 patients with leprosy, increased levels of deprivation were associated with an increased risk of leprosy in Brazil. Directions of effect were consistent in children younger than 15 years and across disease subtypes. Individuals residing in regions with the highest poverty in the country (central-west, north, and northeast regions) had a risk of leprosy incidence five-to-eight times greater than did other individuals. Decreased levels of income and education and factors reflecting unfavourable living conditions were associated with an up to two-times increase in leprosy incidence (incidence rate ratio 1·46, 95% CI 1·32-1·62, for lowest vs highest quartile of income per capita; 2·09, 95% CI 1·62-2·72, for lowest vs highest level of education). INTERPRETATION Within the poorest half of the Brazilian population, the most deprived individuals have the greatest risk of leprosy. Strategies focusing on early detection and treatment in the poorest populations could contribute substantially to global disease control. FUNDING Medical Research Council, Wellcome Trust, Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (Brazil), the Conselho Nacional das Fundações Estaduais de Amparo à Pesquisa, Economic and Social Research Council, Biotechnology and Biological Sciences Research Council, Conselho Nacional de Desenvolvimento Científico e Tecnológico, and Fundação de Apoio à Pesquisa do Distrito Federal.
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Affiliation(s)
- Joilda Silva Nery
- Instituto de Saúde Coletiva, Universidade Federal da Bahia, Salvador, Brazil.
| | - Anna Ramond
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, UK
| | - Julia Moreira Pescarini
- Centro de Integração de Dados e Conhecimentos para Saúde, Fundação Oswaldo Cruz, Salvador, Brazil
| | - André Alves
- Centro de Integração de Dados e Conhecimentos para Saúde, Fundação Oswaldo Cruz, Salvador, Brazil
| | - Agostino Strina
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, UK; Centro de Integração de Dados e Conhecimentos para Saúde, Fundação Oswaldo Cruz, Salvador, Brazil
| | - Maria Yury Ichihara
- Centro de Integração de Dados e Conhecimentos para Saúde, Fundação Oswaldo Cruz, Salvador, Brazil
| | | | - Liam Smeeth
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, UK
| | - Laura C Rodrigues
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, UK
| | - Mauricio L Barreto
- Instituto de Saúde Coletiva, Universidade Federal da Bahia, Salvador, Brazil; Centro de Integração de Dados e Conhecimentos para Saúde, Fundação Oswaldo Cruz, Salvador, Brazil
| | - Elizabeth B Brickley
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, UK
| | - Gerson Oliveira Penna
- Tropical Medicine Centre, University of Brasília, Fiocruz School of Goverment Brasília, Brazil
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de Souza CDF, Rocha VS, Santos NF, Leal TC, de Paiva JPS, Oliveira CCC, Martins-Filho PRS, Magalhães MAFM, Cuevas LE, Santos VS. Spatial clustering, social vulnerability and risk of leprosy in an endemic area in Northeast Brazil: an ecological study. J Eur Acad Dermatol Venereol 2019; 33:1581-1590. [PMID: 30903718 DOI: 10.1111/jdv.15596] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 03/12/2019] [Indexed: 11/29/2022]
Abstract
BACKGROUND Despite the global decline in the detection of leprosy cases, its incidence has remained unchanged in certain settings and requires the determination of the factors linked to its persistence. We examined the spatial and space-time distribution of leprosy and the influence of social vulnerability on the occurrence of the disease in an endemic area of Northeast Brazil. METHODS We performed an ecological study of all leprosy cases reported by Sergipe state, Northeast Brazil from 2001 to 2015, to examine the association of the Social Vulnerability Index and the prevalence and persistence of leprosy among the State's municipalities. Socio-economic and leprosy surveillance information was collected from the Brazilian information systems, and a Bayesian empirical local model was used to identify fluctuations of the indicators. Spatial and space-time clusters were identified using scan spatial statistic tests and to measure the municipalities' relative risk of leprosy. RESULTS Leprosy clusters and burden of disease had a strong statistical association with the municipalities' Social Vulnerability Index. Municipalities with a high social vulnerability had higher leprosy incidence, multibacillary leprosy and newly diagnosed cases with grade 2 disability than areas with low social vulnerability. CONCLUSION Social vulnerability is strongly associated with leprosy transmission and maintenance of disease incidence. Leprosy control programmes should be targeted to the populations with high social vulnerability.
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Affiliation(s)
- C D F de Souza
- Centre for Epidemiology and Public Health, Federal University of Alagoas, Arapiraca, Brazil
| | - V S Rocha
- Tiradentes University, Aracaju, Brazil
| | | | - T C Leal
- Centre for Epidemiology and Public Health, Federal University of Alagoas, Arapiraca, Brazil
| | - J P S de Paiva
- Centre for Epidemiology and Public Health, Federal University of Alagoas, Arapiraca, Brazil
| | | | - P R S Martins-Filho
- Investigative Pathology Laboratory, Federal University of Sergipe, Aracaju, Brazil
| | - M A F M Magalhães
- Instituto de Comunicação e Informação Científica e Tecnológica em Saúde, Fundação Oswaldo Cruz (ICICT- Fiocruz), Rio de Janeiro, Brazil
| | - L E Cuevas
- Department of Clinical Science, Liverpool School of Tropical Medicine, Liverpool, UK
| | - V S Santos
- Centre for Epidemiology and Public Health, Federal University of Alagoas, Arapiraca, Brazil
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Exploring Spatial Influence of Remotely Sensed PM2.5 Concentration Using a Developed Deep Convolutional Neural Network Model. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2019; 16:ijerph16030454. [PMID: 30720752 PMCID: PMC6388139 DOI: 10.3390/ijerph16030454] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 01/24/2019] [Accepted: 01/24/2019] [Indexed: 11/17/2022]
Abstract
Currently, more and more remotely sensed data are being accumulated, and the spatial analysis methods for remotely sensed data, especially big data, are desiderating innovation. A deep convolutional network (CNN) model is proposed in this paper for exploiting the spatial influence feature in remotely sensed data. The method was applied in investigating the magnitude of the spatial influence of four factors—population, gross domestic product (GDP), terrain, land-use and land-cover (LULC)—on remotely sensed PM2.5 concentration over China. Satisfactory results were produced by the method. It demonstrates that the deep CNN model can be well applied in the field of spatial analysing remotely sensed big data. And the accuracy of the deep CNN is much higher than of geographically weighted regression (GWR) based on comparation. The results showed that population spatial density, GDP spatial density, terrain, and LULC could together determine the spatial distribution of PM2.5 annual concentrations with an overall spatial influencing magnitude of 97.85%. Population, GDP, terrain, and LULC have individual spatial influencing magnitudes of 47.12% and 36.13%, 50.07% and 40.91% on PM2.5 annual concentrations respectively. Terrain and LULC are the dominating spatial influencing factors, and only these two factors together may approximately determine the spatial pattern of PM2.5 annual concentration over China with a high spatial influencing magnitude of 96.65%.
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Freitas LRSD, Duarte EC, Garcia LP. Analysis of the epidemiological situation of leprosy in an endemic area in Brazil: spatial distribution in the periods 2001 - 2003 and 2010 - 2012. REVISTA BRASILEIRA DE EPIDEMIOLOGIA 2018; 20:702-713. [PMID: 29267754 DOI: 10.1590/1980-5497201700040012] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Accepted: 07/11/2017] [Indexed: 11/22/2022] Open
Abstract
INTRODUCTION In Brazil, the spatial distribution of leprosy is heterogeneous. Areas with high transmission of the disease remain in the North, Center-west and Northeast. Areas with high transmission of the disease remain in the Northern, Central-Western and Northeastern regions of the country. OBJECTIVE to describe the spatial distribution of leprosy in municipalities with high risk of transmission, in the periods from 2001 - 2003 and 2010 - 2012. METHODS This was an ecological study using data from the Notifiable Diseases Information System (SINAN). They included all municipalities in the states of Mato Grosso, Tocantins, Rondônia, Pará and Maranhão. The following leprosy indicators were calculated per 100,000 inhabitants: incidence rate of leprosy, incidence rate in children aged less than 15 years and rate of new cases with grade 2 disabilities. The spatial scan statistic was used to detect significant clusters (p ≤ 0.05) in the study area. RESULTS In the period 2001 - 2003, the scan spatial statistics identified 44 significant clusters for the leprosy incidence rate, and 42 significant clusters in the period 2010 - 2012. In the period 2001 - 2003, it was possible to identify 20 significant clusters to the incidence rate in children aged less than 15, and 14 significant clusters in the period 2010 - 2012. For the rate of new cases with grade 2 disability, the scan statistics identified 19 significant clusters in the period 2001 - 2003, and 14 significant clusters in the period 2010 - 2012. CONCLUSIONS Despite the reduction in the detection of leprosy cases, there is a need intensify disease control actions, especially in the clusters identified.
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Pescarini JM, Strina A, Nery JS, Skalinski LM, de Andrade KVF, Penna MLF, Brickley EB, Rodrigues LC, Barreto ML, Penna GO. Socioeconomic risk markers of leprosy in high-burden countries: A systematic review and meta-analysis. PLoS Negl Trop Dis 2018; 12:e0006622. [PMID: 29985930 PMCID: PMC6053250 DOI: 10.1371/journal.pntd.0006622] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Revised: 07/19/2018] [Accepted: 06/19/2018] [Indexed: 11/18/2022] Open
Abstract
Over 200,000 new cases of leprosy are detected each year, of which approximately 7% are associated with grade-2 disabilities (G2Ds). For achieving leprosy elimination, one of the main challenges will be targeting higher risk groups within endemic communities. Nevertheless, the socioeconomic risk markers of leprosy remain poorly understood. To address this gap we systematically reviewed MEDLINE/PubMed, Embase, LILACS and Web of Science for original articles investigating the social determinants of leprosy in countries with > 1000 cases/year in at least five years between 2006 and 2016. Cohort, case-control, cross-sectional, and ecological studies were eligible for inclusion; qualitative studies, case reports, and reviews were excluded. Out of 1,534 non-duplicate records, 96 full-text articles were reviewed, and 39 met inclusion criteria. 17 were included in random-effects meta-analyses for sex, occupation, food shortage, household contact, crowding, and lack of clean (i.e., treated) water. The majority of studies were conducted in Brazil, India, or Bangladesh while none were undertaken in low-income countries. Descriptive synthesis indicated that increased age, poor sanitary and socioeconomic conditions, lower level of education, and food-insecurity are risk markers for leprosy. Additionally, in pooled estimates, leprosy was associated with being male (RR = 1.33, 95% CI = 1.06-1.67), performing manual labor (RR = 2.15, 95% CI = 0.97-4.74), suffering from food shortage in the past (RR = 1.39, 95% CI = 1.05-1.85), being a household contact of a leprosy patient (RR = 3.40, 95% CI = 2.24-5.18), and living in a crowded household (≥5 per household) (RR = 1.38, 95% CI = 1.14-1.67). Lack of clean water did not appear to be a risk marker of leprosy (RR = 0.94, 95% CI = 0.65-1.35). Additionally, ecological studies provided evidence that lower inequality, better human development, increased healthcare coverage, and cash transfer programs are linked with lower leprosy risks. These findings point to a consistent relationship between leprosy and unfavorable economic circumstances and, thereby, underscore the pressing need of leprosy control policies to target socially vulnerable groups in high-burden countries.
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Affiliation(s)
- Julia Moreira Pescarini
- Centro de Integração de Dados e Conhecimentos para Saúde (Cidacs), Fundação Oswaldo Cruz, Salvador, Brazil
| | - Agostino Strina
- Centro de Integração de Dados e Conhecimentos para Saúde (Cidacs), Fundação Oswaldo Cruz, Salvador, Brazil
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Joilda Silva Nery
- Centro de Integração de Dados e Conhecimentos para Saúde (Cidacs), Fundação Oswaldo Cruz, Salvador, Brazil
- Universidade Federal do Vale do São Francisco (UNIVASF), Paulo Afonso, Brazil
| | - Lacita Menezes Skalinski
- Instituto de Saúde Coletiva, Universidade Federal da Bahia, Salvador, Brazil
- Universidade Estadual de Santa Cruz (UESC), Ilheus, Brazil
| | - Kaio Vinicius Freitas de Andrade
- Instituto de Saúde Coletiva, Universidade Federal da Bahia, Salvador, Brazil
- Universidade Estadual de Feira de Santana (UEFS), Feira de Santana, Brazil
| | - Maria Lucia F. Penna
- Universidade Federal Fluminense, Instituto de Saúde da Comunidade, Niterói, Brazil
| | - Elizabeth B. Brickley
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Laura C. Rodrigues
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Mauricio Lima Barreto
- Centro de Integração de Dados e Conhecimentos para Saúde (Cidacs), Fundação Oswaldo Cruz, Salvador, Brazil
- Instituto de Saúde Coletiva, Universidade Federal da Bahia, Salvador, Brazil
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Duarte-Cunha M, Almeida ASD, Cunha GMD, Souza-Santos R. Geographic weighted regression: applicability to epidemiological studies of leprosy. Rev Soc Bras Med Trop 2017; 49:74-82. [PMID: 27163567 DOI: 10.1590/0037-8682-0307-2015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Accepted: 11/30/2015] [Indexed: 11/22/2022] Open
Abstract
INTRODUCTION Geographic information systems (GIS) enable public health data to be analyzed in terms of geographical variability and the relationship between risk factors and diseases. This study discusses the application of the geographic weighted regression (GWR) model to health data to improve the understanding of spatially varying social and clinical factors that potentially impact leprosy prevalence. METHODS This ecological study used data from leprosy case records from 1998-2006, aggregated by neighborhood in the Duque de Caxias municipality in the State of Rio de Janeiro, Brazil. In the GWR model, the associations between the log of the leprosy detection rate and social and clinical factors were analyzed. RESULTS Maps of the estimated coefficients by neighborhood confirmed the heterogeneous spatial relationships between the leprosy detection rates and the predictors. The proportion of households with piped water was associated with higher detection rates, mainly in the northeast of the municipality. Indeterminate forms were strongly associated with higher detections rates in the south, where access to health services was more established. CONCLUSIONS GWR proved a useful tool for epidemiological analysis of leprosy in a local area, such as Duque de Caxias. Epidemiological analysis using the maps of the GWR model offered the advantage of visualizing the problem in sub-regions and identifying any spatial dependence in the local study area.
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Affiliation(s)
- Mônica Duarte-Cunha
- Departamento de Vigilância em Saúde, Secretaria Municipal de Saúde de Duque de Caxias, Duque de Caxias, Rio de Janeiro, Brazil
| | - Andréa Sobral de Almeida
- Departamento de Endemias Samuel Pessoa, Escola Nacional de Saúde Pública, Fundação Oswaldo Cruz, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Geraldo Marcelo da Cunha
- Departamento de Epidemiologia, Escola Nacional de Saúde Pública, Fundação Oswaldo Cruz, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Reinaldo Souza-Santos
- Departamento de Endemias Samuel Pessoa, Escola Nacional de Saúde Pública, Fundação Oswaldo Cruz, Rio de Janeiro, Rio de Janeiro, Brazil
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Blok DJ, De Vlas SJ, Richardus JH. Global elimination of leprosy by 2020: are we on track? Parasit Vectors 2015; 8:548. [PMID: 26490878 PMCID: PMC4618543 DOI: 10.1186/s13071-015-1143-4] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2015] [Accepted: 10/03/2015] [Indexed: 01/06/2023] Open
Abstract
BACKGROUND Every year more than 200,000 new leprosy cases are registered globally. This number has been fairly stable over the past 8 years. WHO has set a target to interrupt the transmission of leprosy globally by 2020. The aim of this study is to investigate whether this target, interpreted as global elimination, is feasible given the current control strategy. We focus on the three most important endemic countries, India, Brazil and Indonesia, which together account for more than 80 % of all newly registered leprosy cases. METHODS We used the existing individual-based model SIMCOLEP to predict future trends of leprosy incidence given the current control strategy in each country. SIMCOLEP simulates the spread of M. leprae in a population that is structured in households. Current control consists of passive and active case detection, and multidrug therapy (MDT). Predictions of leprosy incidence were made for each country as well as for one high-endemic region within each country: Chhattisgarh (India), Pará State (Brazil) and Madura (Indonesia). Data for model quantification came from: National Leprosy Elimination Program (India), SINAN database (Brazil), and Netherlands Leprosy Relief (Indonesia). RESULTS Our projections of future leprosy incidence all show a downward trend. In 2020, the country-level leprosy incidence has decreased to 6.2, 6.1 and 3.3 per 100,000 in India, Brazil and Indonesia, respectively, meeting the elimination target of less than 10 per 100,000. However, elimination may not be achieved in time for the high-endemic regions. The leprosy incidence in 2020 is predicted to be 16.2, 21.1 and 19.3 per 100,000 in Chhattisgarh, Pará and Madura, respectively, and the target may only be achieved in another 5 to 10 years. CONCLUSIONS Our predictions show that although country-level elimination is reached by 2020, leprosy is likely to remain a problem in the high-endemic regions (i.e. states, districts and provinces with multimillion populations), which account for most of the cases in a country.
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Affiliation(s)
- David J Blok
- Department of Public Health, Erasmus MC, University Medical Center, P.O. Box 2040, Rotterdam, CA, 3000, The Netherlands.
| | - Sake J De Vlas
- Department of Public Health, Erasmus MC, University Medical Center, P.O. Box 2040, Rotterdam, CA, 3000, The Netherlands.
| | - Jan Hendrik Richardus
- Department of Public Health, Erasmus MC, University Medical Center, P.O. Box 2040, Rotterdam, CA, 3000, The Netherlands.
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Abstract
Leprosy or Hansen's disease is an infectious disease caused by the bacterium Mycobacterium leprae. The annual number of new leprosy cases registered worldwide has remained stable over the past years at over 200,000. Early case finding and multidrug therapy have not been able interrupt transmission completely. Elimination requires innovation in control and sustained commitment. Mathematical models can be used to predict the course of leprosy incidence and the effect of intervention strategies. Two compartmental models and one individual-based model have been described in the literature. Both compartmental models investigate the course of leprosy in populations and the long-term impact of control strategies. The individual-based model focusses on transmission within households and the impact of case finding among contacts of new leprosy patients. Major improvement of these models should result from a better understanding of individual differences in exposure to infection and developing leprosy after exposure. Most relevant are contact heterogeneity, heterogeneity in susceptibility and spatial heterogeneity. Furthermore, the existing models have only been applied to a limited number of countries. Parameterization of the models for other areas, in particular those with high incidence, is essential to support current initiatives for the global elimination of leprosy. Many challenges remain in understanding and dealing with leprosy. The support of mathematical models for understanding leprosy epidemiology and supporting policy decision making remains vital.
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Lyseen AK, Nøhr C, Sørensen EM, Gudes O, Geraghty EM, Shaw NT, Bivona-Tellez C. A Review and Framework for Categorizing Current Research and Development in Health Related Geographical Information Systems (GIS) Studies. Yearb Med Inform 2014; 9:110-24. [PMID: 25123730 DOI: 10.15265/iy-2014-0008] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
OBJECTIVES The application of GIS in health science has increased over the last decade and new innovative application areas have emerged. This study reviews the literature and builds a framework to provide a conceptual overview of the domain, and to promote strategic planning for further research of GIS in health. METHOD The framework is based on literature from the library databases Scopus and Web of Science. The articles were identified based on keywords and initially selected for further study based on titles and abstracts. A grounded theory-inspired method was applied to categorize the selected articles in main focus areas. Subsequent frequency analysis was performed on the identified articles in areas of infectious and non-infectious diseases and continent of origin. RESULTS A total of 865 articles were included. Four conceptual domains within GIS in health sciences comprise the framework: spatial analysis of disease, spatial analysis of health service planning, public health, health technologies and tools. Frequency analysis by disease status and location show that malaria and schistosomiasis are the most commonly analyzed infectious diseases where cancer and asthma are the most frequently analyzed non-infectious diseases. Across categories, articles from North America predominate, and in the category of spatial analysis of diseases an equal number of studies concern Asia. CONCLUSION Spatial analysis of diseases and health service planning are well-established research areas. The development of future technologies and new application areas for GIS and data-gathering technologies such as GPS, smartphones, remote sensing etc. will be nudging the research in GIS and health.
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Affiliation(s)
- A K Lyseen
- Anders Knørr Lyseen, Department of Development and Planning, Aalborg University, Aalborg, Denmark, E-mail:
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14
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Barreto JG, Bisanzio D, Guimarães LDS, Spencer JS, Vazquez-Prokopec GM, Kitron U, Salgado CG. Spatial analysis spotlighting early childhood leprosy transmission in a hyperendemic municipality of the Brazilian Amazon region. PLoS Negl Trop Dis 2014; 8:e2665. [PMID: 24516679 PMCID: PMC3916250 DOI: 10.1371/journal.pntd.0002665] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Accepted: 12/12/2013] [Indexed: 12/05/2022] Open
Abstract
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.
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Affiliation(s)
- Josafá Gonçalves Barreto
- Laboratório de Dermato-Imunologia UEPA/UFPA/Marcello Candia, Marituba, Pará, Brasil
- Universidade Federal do Pará, Campus Castanhal, Pará, Brasil
| | - Donal Bisanzio
- Department of Environmental Studies, Emory University, Atlanta, Georgia, United States of America
| | - Layana de Souza Guimarães
- Unidade de Referência Especializada em Dermatologia Sanitária Dr. Marcello Candia, Marituba, Pará, Brasil
| | - John Stewart Spencer
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, United States of America
| | | | - Uriel Kitron
- Department of Environmental Studies, Emory University, Atlanta, Georgia, United States of America
| | - Claudio Guedes Salgado
- Laboratório de Dermato-Imunologia UEPA/UFPA/Marcello Candia, Marituba, Pará, Brasil
- Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém, Pará, Brasil
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Malizia N. Inaccuracy, uncertainty and the space-time permutation scan statistic. PLoS One 2013; 8:e52034. [PMID: 23408930 PMCID: PMC3567134 DOI: 10.1371/journal.pone.0052034] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Accepted: 11/13/2012] [Indexed: 01/04/2023] Open
Abstract
The space-time permutation scan statistic (STPSS) is designed to identify hot (and cool) spots of space-time interaction within patterns of spatio-temporal events. While the method has been adopted widely in practice, there has been little consideration of the effect inaccurate and/or incomplete input data may have on its results. Given the pervasiveness of inaccuracy, uncertainty and incompleteness within spatio-temporal datasets and the popularity of the method, this issue warrants further investigation. Here, a series of simulation experiments using both synthetic and real-world data are carried out to better understand how deficiencies in the spatial and temporal accuracy as well as the completeness of the input data may affect results of the STPSS. The findings, while specific to the parameters employed here, reveal a surprising robustness of the method's results in the face of these deficiencies. As expected, the experiments illustrate that greater degradation of input data quality leads to greater variability in the results. Additionally, they show that weaker signals of space-time interaction are those most affected by the introduced deficiencies. However, in stark contrast to previous investigations into the impact of these input data problems on global tests of space-time interaction, this local metric is revealed to be only minimally affected by the degree of inaccuracy and incompleteness introduced in these experiments.
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Affiliation(s)
- Nicholas Malizia
- GeoDa Center for Geospatial Analysis and Computation, School of Geographical Sciences and Urban Planning, Arizona State University, Tempe, Arizona, USA.
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Tatem AJ, Adamo S, Bharti N, Burgert CR, Castro M, Dorelien A, Fink G, Linard C, John M, Montana L, Montgomery MR, Nelson A, Noor AM, Pindolia D, Yetman G, Balk D. Mapping populations at risk: improving spatial demographic data for infectious disease modeling and metric derivation. Popul Health Metr 2012; 10:8. [PMID: 22591595 PMCID: PMC3487779 DOI: 10.1186/1478-7954-10-8] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Accepted: 04/27/2012] [Indexed: 11/10/2022] Open
Abstract
The use of Global Positioning Systems (GPS) and Geographical Information Systems (GIS) in disease surveys and reporting is becoming increasingly routine, enabling a better understanding of spatial epidemiology and the improvement of surveillance and control strategies. In turn, the greater availability of spatially referenced epidemiological data is driving the rapid expansion of disease mapping and spatial modeling methods, which are becoming increasingly detailed and sophisticated, with rigorous handling of uncertainties. This expansion has, however, not been matched by advancements in the development of spatial datasets of human population distribution that accompany disease maps or spatial models.Where risks are heterogeneous across population groups or space or dependent on transmission between individuals, spatial data on human population distributions and demographic structures are required to estimate infectious disease risks, burdens, and dynamics. The disease impact in terms of morbidity, mortality, and speed of spread varies substantially with demographic profiles, so that identifying the most exposed or affected populations becomes a key aspect of planning and targeting interventions. Subnational breakdowns of population counts by age and sex are routinely collected during national censuses and maintained in finer detail within microcensus data. Moreover, demographic and health surveys continue to collect representative and contemporary samples from clusters of communities in low-income countries where census data may be less detailed and not collected regularly. Together, these freely available datasets form a rich resource for quantifying and understanding the spatial variations in the sizes and distributions of those most at risk of disease in low income regions, yet at present, they remain unconnected data scattered across national statistical offices and websites.In this paper we discuss the deficiencies of existing spatial population datasets and their limitations on epidemiological analyses. We review sources of detailed, contemporary, freely available and relevant spatial demographic data focusing on low income regions where such data are often sparse and highlight the value of incorporating these through a set of examples of their application in disease studies. Moreover, the importance of acknowledging, measuring, and accounting for uncertainty in spatial demographic datasets is outlined. Finally, a strategy for building an open-access database of spatial demographic data that is tailored to epidemiological applications is put forward.
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Affiliation(s)
- Andrew J Tatem
- Department of Geography, University of Florida, Gainesville, USA.
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Linard C, Tatem AJ. Large-scale spatial population databases in infectious disease research. Int J Health Geogr 2012; 11:7. [PMID: 22433126 PMCID: PMC3331802 DOI: 10.1186/1476-072x-11-7] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2012] [Accepted: 03/20/2012] [Indexed: 01/26/2023] Open
Abstract
Modelling studies on the spatial distribution and spread of infectious diseases are becoming increasingly detailed and sophisticated, with global risk mapping and epidemic modelling studies now popular. Yet, in deriving populations at risk of disease estimates, these spatial models must rely on existing global and regional datasets on population distribution, which are often based on outdated and coarse resolution data. Moreover, a variety of different methods have been used to model population distribution at large spatial scales. In this review we describe the main global gridded population datasets that are freely available for health researchers and compare their construction methods, and highlight the uncertainties inherent in these population datasets. We review their application in past studies on disease risk and dynamics, and discuss how the choice of dataset can affect results. Moreover, we highlight how the lack of contemporary, detailed and reliable data on human population distribution in low income countries is proving a barrier to obtaining accurate large-scale estimates of population at risk and constructing reliable models of disease spread, and suggest research directions required to further reduce these barriers.
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Affiliation(s)
- Catherine Linard
- Biological Control and Spatial Ecology, Université Libre de Bruxelles, CP 160/12, Avenue FD Roosevelt 50, B-1050 Brussels, Belgium.
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Alencar CH, Ramos AN, dos Santos ES, Richter J, Heukelbach J. Clusters of leprosy transmission and of late diagnosis in a highly endemic area in Brazil: focus on different spatial analysis approaches. Trop Med Int Health 2012; 17:518-25. [PMID: 22248041 DOI: 10.1111/j.1365-3156.2011.02945.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVE The Brazilian National Hansen's Disease Control Program recently identified clusters with high disease transmission. Herein, we present different spatial analytical approaches to define highly vulnerable areas in one of these clusters. METHOD The study area included 373 municipalities in the four Brazilian states Maranhão, Pará, Tocantins and Piauí. Spatial analysis was based on municipalities as the observation unit, considering the following disease indicators: (i) rate of new cases/100,000 population, (ii) rate of cases <15 years/100,000 population, (iii) new cases with grade-2 disability/100,000 population and (iv) proportion of new cases with grade-2 disabilities. We performed descriptive spatial analysis, local empirical Bayesian analysis and spatial scan statistic. RESULTS A total of 254 (68.0%) municipalities were classified as hyperendemic (mean annual detection rates >40 cases/100,000 inhabitants). There was a concentration of municipalities with higher detection rates in Pará and in the center of Maranhão. Spatial scan statistic identified 23 likely clusters of new leprosy case detection rates, most of them localized in these two states. These clusters included only 32% of the total population, but 55.4% of new leprosy cases. We also identified 16 significant clusters for the detection rate <15 years and 11 likely clusters of new cases with grade-2. Several clusters of new cases with grade-2/population overlap with those of new cases detection and detection of children <15 years of age. The proportion of new cases with grade-2 did not reveal any significant clusters. CONCLUSIONS Several municipality clusters for high leprosy transmission and late diagnosis were identified in an endemic area using different statistical approaches. Spatial scan statistic is adequate to validate and confirm high-risk leprosy areas for transmission and late diagnosis, identified using descriptive spatial analysis and using local empirical Bayesian method. National and State leprosy control programs urgently need to intensify control actions in these highly vulnerable municipalities.
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Affiliation(s)
- Carlos H Alencar
- Department of Community Health, School of Medicine, Federal University of Ceará, Fortaleza, Brazil
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Cury MRDCO, Paschoal VD, Nardi SMT, Chierotti AP, Rodrigues Júnior AL, Chiaravalloti-Neto F. Spatial analysis of leprosy incidence and associated socioeconomic factors. Rev Saude Publica 2011; 46:110-8. [PMID: 22183514 DOI: 10.1590/s0034-89102011005000086] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2011] [Accepted: 07/26/2011] [Indexed: 11/22/2022] Open
Abstract
OBJECTIVE To identify clusters of the major occurrences of leprosy and their associated socioeconomic and demographic factors. METHODS Cases of leprosy that occurred between 1998 and 2007 in São José do Rio Preto (southeastern Brazil) were geocodified and the incidence rates were calculated by census tract. A socioeconomic classification score was obtained using principal component analysis of socioeconomic variables. Thematic maps to visualize the spatial distribution of the incidence of leprosy with respect to socioeconomic levels and demographic density were constructed using geostatistics. RESULTS While the incidence rate for the entire city was 10.4 cases per 100,000 inhabitants annually between 1998 and 2007, the incidence rates of individual census tracts were heterogeneous, with values that ranged from 0 to 26.9 cases per 100,000 inhabitants per year. Areas with a high leprosy incidence were associated with lower socioeconomic levels. There were identified clusters of leprosy cases, however there was no association between disease incidence and demographic density. There was a disparity between the places where the majority of ill people lived and the location of healthcare services. CONCLUSIONS The spatial analysis techniques utilized identified the poorer neighborhoods of the city as the areas with the highest risk for the disease. These data show that health departments must prioritize politico-administrative policies to minimize the effects of social inequality and improve the standards of living, hygiene, and education of the population in order to reduce the incidence of leprosy.
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Wen L, Li C, Lin M, Yuan Z, Huo D, Li S, Wang Y, Chu C, Jia R, Song H. Spatio-temporal analysis of malaria incidence at the village level in a malaria-endemic area in Hainan, China. Malar J 2011; 10:88. [PMID: 21492475 PMCID: PMC3094226 DOI: 10.1186/1475-2875-10-88] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2010] [Accepted: 04/14/2011] [Indexed: 12/04/2022] Open
Abstract
BACKGROUND Malaria incidence in China's Hainan province has dropped significantly, since Malaria Programme of China Global Fund Round 1 was launched. To lay a foundation for further studies to evaluate the efficacy of Malaria Programme and to help with public health planning and resource allocation in the future, the temporal and spatial variations of malaria epidemic are analysed and areas and seasons with a higher risk are identified at a fine geographic scale within a malaria endemic county in Hainan. METHODS Malaria cases among the residents in each of 37 villages within hyper-endemic areas of Wanning county in southeast Hainan from 2005 to 2009 were geo-coded at village level based on residence once the patients were diagnosed. Based on data so obtained, purely temporal, purely spatial and space-time scan statistics and geographic information systems (GIS) were employed to identify clusters of time, space and space-time with elevated proportions of malaria cases. RESULTS Purely temporal scan statistics suggested clusters in 2005,2006 and 2007 and no cluster in 2008 and 2009. Purely spatial clustering analyses pinpointed the most likely cluster as including three villages in 2005 and 2006 respectively, sixteen villages in 2007, nine villages in 2008, and five villages in 2009, and the south area of Nanqiao town as the most likely to have a significantly high occurrence of malaria. The space-time clustering analysis found the most likely cluster as including three villages in the south of Nanqiao town with a time frame from January 2005 to May 2007. CONCLUSIONS Even in a small traditional malaria endemic area, malaria incidence has a significant spatial and temporal heterogeneity on the finer spatial and temporal scales. The scan statistics enable the description of this spatiotemporal heterogeneity, helping with clarifying the epidemiology of malaria and prioritizing the resource assignment and investigation of malaria on a finer geographical scale in endemic areas.
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Affiliation(s)
- Liang Wen
- PLA Institute of Disease Control and Prevention, Beijing, China
| | - Chengyi Li
- PLA Institute of Disease Control and Prevention, Beijing, China
| | - Minghe Lin
- Wanning Health and Epidemic Prevention Station, Wanning County, Hainan province, China
| | - Zhengquan Yuan
- PLA Institute of Disease Control and Prevention, Beijing, China
| | - Donghui Huo
- PLA Institute of Disease Control and Prevention, Beijing, China
| | - Shenlong Li
- PLA Institute of Disease Control and Prevention, Beijing, China
| | - Yong Wang
- PLA Institute of Disease Control and Prevention, Beijing, China
| | - Chenyi Chu
- PLA Institute of Disease Control and Prevention, Beijing, China
| | - Ruizhong Jia
- PLA Institute of Disease Control and Prevention, Beijing, China
| | - Hongbin Song
- PLA Institute of Disease Control and Prevention, Beijing, China
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Tatem AJ, Campiz N, Gething PW, Snow RW, Linard C. The effects of spatial population dataset choice on estimates of population at risk of disease. Popul Health Metr 2011; 9:4. [PMID: 21299885 PMCID: PMC3045911 DOI: 10.1186/1478-7954-9-4] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2010] [Accepted: 02/07/2011] [Indexed: 11/17/2022] Open
Abstract
Background The spatial modeling of infectious disease distributions and dynamics is increasingly being undertaken for health services planning and disease control monitoring, implementation, and evaluation. Where risks are heterogeneous in space or dependent on person-to-person transmission, spatial data on human population distributions are required to estimate infectious disease risks, burdens, and dynamics. Several different modeled human population distribution datasets are available and widely used, but the disparities among them and the implications for enumerating disease burdens and populations at risk have not been considered systematically. Here, we quantify some of these effects using global estimates of populations at risk (PAR) of P. falciparum malaria as an example. Methods The recent construction of a global map of P. falciparum malaria endemicity enabled the testing of different gridded population datasets for providing estimates of PAR by endemicity class. The estimated population numbers within each class were calculated for each country using four different global gridded human population datasets: GRUMP (~1 km spatial resolution), LandScan (~1 km), UNEP Global Population Databases (~5 km), and GPW3 (~5 km). More detailed assessments of PAR variation and accuracy were conducted for three African countries where census data were available at a higher administrative-unit level than used by any of the four gridded population datasets. Results The estimates of PAR based on the datasets varied by more than 10 million people for some countries, even accounting for the fact that estimates of population totals made by different agencies are used to correct national totals in these datasets and can vary by more than 5% for many low-income countries. In many cases, these variations in PAR estimates comprised more than 10% of the total national population. The detailed country-level assessments suggested that none of the datasets was consistently more accurate than the others in estimating PAR. The sizes of such differences among modeled human populations were related to variations in the methods, input resolution, and date of the census data underlying each dataset. Data quality varied from country to country within the spatial population datasets. Conclusions Detailed, highly spatially resolved human population data are an essential resource for planning health service delivery for disease control, for the spatial modeling of epidemics, and for decision-making processes related to public health. However, our results highlight that for the low-income regions of the world where disease burden is greatest, existing datasets display substantial variations in estimated population distributions, resulting in uncertainty in disease assessments that utilize them. Increased efforts are required to gather contemporary and spatially detailed demographic data to reduce this uncertainty, particularly in Africa, and to develop population distribution modeling methods that match the rigor, sophistication, and ability to handle uncertainty of contemporary disease mapping and spread modeling. In the meantime, studies that utilize a particular spatial population dataset need to acknowledge the uncertainties inherent within them and consider how the methods and data that comprise each will affect conclusions.
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Affiliation(s)
- Andrew J Tatem
- Department of Geography, University of Florida, Gainesville, USA.
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Fischer E, Pahan D, Chowdhury S, Oskam L, Richardus J. The spatial distribution of leprosy in four villages in Bangladesh: an observational study. BMC Infect Dis 2008; 8:125. [PMID: 18811968 PMCID: PMC2564933 DOI: 10.1186/1471-2334-8-125] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2007] [Accepted: 09/23/2008] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND There is a higher case-detection rate for leprosy among spatially proximate contacts such as household members and neighbors. Spatial information regarding the clustering of leprosy can be used to improve intervention strategies. Identifying high-risk areas within villages around known cases can be helpful in finding new cases. METHODS Using geographic information systems, we created digital maps of four villages in a highly endemic area in northwest Bangladesh. The villages were surveyed three times over four years. The spatial pattern of the compounds--a small group of houses--was analyzed, and we looked for spatial clusters of leprosy cases. RESULTS The four villages had a total population of 4,123. There were 14 previously treated patients and we identified 19 new leprosy patients during the observation period. However, we found no spatial clusters with a probability significantly different from the null hypothesis of random occurrence. CONCLUSION Spatial analysis at the microlevel of villages in highly endemic areas does not appear to be useful for identifying clusters of patients. The search for clustering should be extended to a higher aggregation level, such as the subdistrict or regional level. Additionally, in highly endemic areas, it appears to be more effective to target complete villages for contact tracing, rather than narrowly defined contact groups such as households.
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Affiliation(s)
- Eaj Fischer
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands.
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