Study contributions

Main results

A total of 4,029 leprosy cases were notified. Mean prevalence varied between 2.0 and 11.5 cases/10,000 inhab. Spatial distribution of the cases was heterogeneous and there was a falling prevalence trend over the years studied.

Implications for services

These findings point to the need to strengthen active tracing strategies and expand health actions and services targeting leprosy, with the aim of increasing detection and early treatment of cases.

Perspectives

It is important to carry out epidemiological investigations on the spatial distribution and prevalence of leprosy in other health regions in the state, in order to identify other areas with greater vulnerability to leprosy.

Keywords:
Leprosy; Prevalence; Spatial Analysis; Epidemiology; Ecological Studies

Abstract

Objective:

to analyse the spatial distribution and trend of leprosy in municipalities of a health region in a Northeast Brazilian state.

Methods:

this was an ecological time-series study based on compulsory notification of leprosy cases by the municipalities covered by the Imperatriz-MA Regional Health Management Unit, between 2008 and 2017; prevalence and mean prevalence for the period were calculated; spatial analysis of the area was carried out and maps were generated using ArcGis 10.5. Prais-Winsten regression was used for trend analysis.

Result:

4,029 cases of the disease were identified, and average prevalence ranged from 2.0 to 11.5 cases/10,000 inhabitants-year. The overall trend was downward. Governador Edson Lobão had the highest prevalence, 11.5 cases/10,000 inhabitants, and Lajeado Novo had the lowest prevalence, 2.0 cases/10,000 inhabitants.

Conclusion:

spatial distribution of leprosy cases was heterogeneous in the municipalities studied and prevalence had a falling trend.

Keywords:
Leprosy; Prevalence; Spatial Analysis; Epidemiology; Ecological Studies

Resumen

Objetivo:

analisar la distribución espacial y la tendencia de la lepra en una región sanitaria de un estado del Nordeste brasileño.

Métodos:

estudio ecológico y de serie temporal, con notificación obligatoria de los municipios de la Unidad de Gestión Regional de Salud de Imperatriz-MA, entre 2008-2017. Se determinaron la prevalencia y la media del período y se realizó un análisis del espacio de área, los mapas se generaron en ArcGis 10.5. Para el análisis de tendencia se utilizaron regresiones de Prais-Winsten.

Resultado:

se identificaron 4.029 casos y las prevalencias promedio oscilaron entre 2,0 y 11,5 casos/10.000 habitantes-año, con tendencia al descenso. Governador Edson Lobão presentó la mayor prevalencia 11,5 casos/10.000 habitantes y Lajeado Novo la menor prevalencia 2,0 casos/10.000 habitantes.

Conclusión:

la distribución espacial de los casos de lepra fue heterogénea en los municipios y la tendencia de prevalencia decreciente.

Palabras-clave:
Lepra; Prevalencia; Análisis Espacial; Epidemiología; Estudios Ecológicos

INTRODUCTION

Leprosy, a communicable disease caused by Mycobacterium leprae, is one of the 20 neglected tropical diseases (NTDs) listed by the World Health Organization (WHO).¹1. World Health Organization. Global leprosy update, 2020: impact of COVID-19 on global leprosy control: weekly epidemiological record. Genebra: World Health Organization; 2021[cited 2021 Nov 17]. 24 p. Available from: Available from: https://www.who.int/publications/i/item/who-wer9636-421-444
https://www.who.int/publications/i/item/... It develops in a slow and progressive manner, leading to deformities and physical disabilities when not properly treated; ²2. Acebrón-García-de-Eulate M, Blundell TL, Vedithi SC. Strategies for drug target identification in Mycobacterium leprae. Drug Discov Today. 2021;26(7):1569-73. doi: 10.1016/j.drudis.2021.03.026^,33. Blok D, Steinmann P, Tiwari A, Barth-Jaeggi T, Arif MA, Banstola N, et al. O impacto a longo prazo do programa de Profilaxia Pós-Exposição da Hanseníase (LPEP) na incidência da hanseníase: um estudo de modelagem. PLoS Negl Trop Dis. 2021;15(3):e0009279. doi: 10.1371/journal.pntd.0009279
https://doi.org/10.1371/journal.pntd.000... and continues to be a serious public health problem, especially in developing countries.¹1. World Health Organization. Global leprosy update, 2020: impact of COVID-19 on global leprosy control: weekly epidemiological record. Genebra: World Health Organization; 2021[cited 2021 Nov 17]. 24 p. Available from: Available from: https://www.who.int/publications/i/item/who-wer9636-421-444
https://www.who.int/publications/i/item/...

In 2020, the WHO registered the occurrence of 127,396 new leprosy cases worldwide. Brazil, India and Indonesia reported 94,299 cases, equivalent to 74% of new cases detected that year. In Brazil, the case detection rate showed a sharp reduction, dropping from 17.7/100,000 inhabitants in 2011 to 8.0/100,000 inhabitants in 2020.⁴4. Ministério da Saúde (BR). Sistema de Informação de Agravos de Notificação: indicadores e dados básicos de hanseníase nos municípios brasileiros. Brasília: Ministério da Saúde; 2022 [2022 Mar 22]. Disponível em: Disponível em: http://indicadoreshanseniase.aids.gov.br/
http://indicadoreshanseniase.aids.gov.br... ^,55. Ministério da Saúde (BR). Secretária de Vigilância em Saúde. Boletim Epidemiológico Especial de Hanseníase [Internet]. Brasília: Ministério da Saúde ; 2022 [citado 2022 Mar 03]. Disponível em: Disponível em: https://www.gov.br/saude/pt-br/centrais-de-conteudo/publicacoes/boletins/epidemiologicos/especiais/2022/boletim-epidemiologico-de-hanseniase-_-25-01-2022.pdf
https://www.gov.br/saude/pt-br/centrais-... It is possible that the significant reduction in cases observed in 2020 is due to the COVID-19 pandemic, which affected disease surveillance and control actions due to the overloading of health systems and services; or perhaps due to people’s movements from one place to another being restricted.⁶6. Paz WS, Souza MR, Tavares DS, Jesus AR, Santos AD, Carmo RF, et al. Impact of the covid-19 pandemic on the diagnosis of leprosy in brazil: an ecological and population-based study. Lancet Reg Health Am. 2022;9:100181. doi: 10.1016/j.lana.2021.100181
https://doi.org/10.1016/j.lana.2021.1001... ^,77. Anjos LHG, Cunha SM, Batista GM, Higino TMM, Souza DCP, Aliança ASS. Epidemiological profile of leprosy in the state of Maranhão from 2018 to 2020. Research, Society and Development. 2021;10(15):e272101523156. doi: 10.33448/rsd-v10i15.23156
https://doi.org/10.33448/rsd-v10i15.2315...

It should also be added that tracing contracts of leprosy cases is the basis of active surveillance and constitutes an important tool for early diagnosis of new cases.³3. Blok D, Steinmann P, Tiwari A, Barth-Jaeggi T, Arif MA, Banstola N, et al. O impacto a longo prazo do programa de Profilaxia Pós-Exposição da Hanseníase (LPEP) na incidência da hanseníase: um estudo de modelagem. PLoS Negl Trop Dis. 2021;15(3):e0009279. doi: 10.1371/journal.pntd.0009279
https://doi.org/10.1371/journal.pntd.000... ^,88. Rajkumar P, Purushothaman GKC, Ponnaiah M, Shanmugasundaram D, Padma J, Meena RL, et al. Low risk of relapse and deformity among leprosy patients who completed the multidrug therapy regimen from 2005 to 2010: a cohort study of four districts in Southern India. PLoS Negl Trop Dis. 2021;15(11):e0009950. doi: 10.1371/journal.pntd.0009950
https://doi.org/10.1371/journal.pntd.000... In this sense, it is relevant to use spatial analysis tools in endemic areas,⁹9. Machado LMG, Santos ES, Cavaliero A, Steinmann P, Ignotti E. Análise espaço-temporal dos riscos da hanseníase em um município do estado de Mato Grosso-Amazônia: resultados do programa de profilaxia pós-exposição à hanseníase no Brasil. Infect Dis Poverty. 2022;11(1):21. doi: 10.1186/s40249-022-00943-7
https://doi.org/10.1186/s40249-022-00943... especially geographic information systems (GIS), which allow identification of space-time distributions, patterns of prevalence and transmissibility of the disease.¹⁰10. Chen X, Shui TJ. The state of the leprosy epidemic in Yunnan, China 2011-2020: a spatial and space-time analysis, highlighting areas for intervention. PLoS Negl Trop Dis. 2021;15(10):e0009783. doi: 10.1371/journal.pntd.0009783
https://doi.org/10.1371/journal.pntd.000...

The objective of this study was to evaluate the spatial distribution and the trend of leprosy in municipalities of a health region of a state in Northeast Brazil.

METHODS

This was an ecological time-series study, using as its ecological units of analysis the 16 municipalities covered by the Imperatriz Regional Health Management Unit (Unidade Gestora Regional de Saúde de Imperatriz - UGRSI), in the state of Maranhão, Brazil (Figure 1). The total estimated population within the region covered by the UGRSI is 511,735 inhabitants. The region has an area of 25,658.205 km²2. Acebrón-García-de-Eulate M, Blundell TL, Vedithi SC. Strategies for drug target identification in Mycobacterium leprae. Drug Discov Today. 2021;26(7):1569-73. doi: 10.1016/j.drudis.2021.03.026.¹¹11. Instituto Brasileiro de Geografia e Estatística. Censo de 2010: características da população e domicílios [Internet]. Rio de Janeiro: Instituto Brasileiro de Geografia e Estatística; 2011 [citado 2022 Abr 26]. 270 p. Disponível em: Disponível em: https://biblioteca.ibge.gov.br/visualizacao/periodicos/93/cd_2010_caracteristicas_populacao_domicilios.pdf
https://biblioteca.ibge.gov.br/visualiza...

The municipalities within the UGRSI are marked by socioeconomic inequalities and vulnerabilities: it is estimated that 24.3% of the population lives in conditions of extreme poverty.¹²12. Anchieta JJS, Costa LMM, Campos LC, Viera MR, Mota OS, Morais Neto OL, et al. Análise de tendência dos indicadores de hanseníase em um estado brasileiro hiperendêmico, 2001-2015. Rev Saude Publica. 2019;53:61. doi: 10.11606/S1518-8787.2019053000752
https://doi.org/10.11606/S1518-8787.2019... As at 2018, this health region had 128 primary healthcare centers, in addition to medium and high complexity health services available in Imperatriz, the municipality where the UGRSI has its headquarters.¹³13. Ministério da Saúde (BR). Cadastro Nacional dos Estabelecimentos de Saúde do Brasil: estabelecimentos por nível de atenção - Maranhão [Internet]. Brasília: Ministério da Saúde ; 2018 [citado 2022 Dez 23]. Disponível em: Disponível em: https://tabnet.datasus.gov.br/cgi/tabcgi.exe?cnes/cnv/atencma.def
https://tabnet.datasus.gov.br/cgi/tabcgi...

The study included secondary data related to the total number of leprosy case notifications held on the Notifiable Health Conditions Information System (Sistema de Informação de Agravos de Notificação - SINAN), for the period from January 2008 to December 2017, by municipality of residence.

Duplicated records were excluded by means of analysis using an Excel spreadsheet in alphabetical order of the full name of each case, as were diagnostic errors, based on the comparison between operational classification and the clinical forms presented. The data were obtained from the UGRSI Health Surveillance Service in September 2021.

Leprosy prevalence was calculated by municipality, dividing the total number of cases diagnosed each year by the estimated population for the municipality, multiplied by 10,000. The annual mean prevalence was calculated by dividing the total number of cases notified during the study period by 10, which corresponds to the total number of years in the series. Population data for the municipalities were retrieved from the website of the Brazilian Institute of Geography and Statistics (Instituto Brasileiro de Geografia e Estatística - IBGE).¹⁴14. Instituto Brasileiro de Geografia e Estatística. Estimativa da população - EstimaPop [Internet]. Rio de Janeiro: Instituto Brasileiro de Geografia e Estatística ; 2018 [citado 2022 Nov 20]. Disponível em: Disponível em: https://sidra.ibge.gov.br/pesquisa/estimapop
https://sidra.ibge.gov.br/pesquisa/estim...

The analysis of the spatial distribution of the leprosy prevalence was carried out using the map database of the municipalities within the UGRSI, acquired via the Imagem/Esri company. The projection used was the Universal Transverse Mercator (UTM) with the regional geodetic system for South America - South American Datum (SAD-69).¹⁵15. Instituto Brasileiro de Geografia e Estatística. Sistemas de referência [internet]. Rio de Janeiro: Instituto Brasileiro de Geografia e Estatística ; 2022 [citado 2023 Mar 13]. 13 p. Disponível em: Disponível em: https://geoftp.ibge.gov.br/informacoes_sobre_posicionamento_geodesico/sirgas/sisref_2.pdf
https://geoftp.ibge.gov.br/informacoes_s... A spatial area analysis was performed,¹⁶16. Câmara G, Carvalho MS. Análise espacial de eventos. In: Druck S, Carvalho MS, Câmara G, Monteiro AVM, editores. Análise espacial de dados geográficos [Internet]. Brasília: Embrapa; 2004 [citado 2022 Nov 05]. cap. 2; p.1-15. Disponível em: Disponível em: http://www.dpi.inpe.br/gilberto/livro/analise/cap2-eventos.pdf
http://www.dpi.inpe.br/gilberto/livro/an... using ArcGis software version 10.5. This application makes it possible to create and manage vector and matrix data from thematic databases.¹⁷17. Andrade FR. Ocorrência da dengue em Santana de Parnaíba e relação com medidas de controle [especialização]. Ocorrência da dengue em Santana de Parnaíba e relação com medidas de controle. São Paulo: Universidade de São Paulo, Faculdade de Saúde Pública, 2012. 40 p. The pattern of leprosy endemicity was classified according to Brazilian Ministry of Health guidelines.¹⁸18. Ministério da Saúde (BR). Secretaria de Vigilância em Saúde. Departamento de Vigilância Epidemiológica das Doenças Transmissíveis. Coordenação Geral de Hanseníase e Doenças em Eliminação. Unidade Técnica do SINAN. Roteiro para uso do Sistema de Informação de Agravos de Notificação - Sinan NET para hanseníase: manual para tabulação dos indicadores de hanseníase [Internet]. Brasília: Ministério da Saúde ; 2018 [citado 2022 Mar 03]. Disponível em: Disponível em: https://portalsinan.saude.gov.br/images/documentos/Agravos/Hanseniase/Manual_tabulacao_dos_indicadores_de_hanseniase.pdf
https://portalsinan.saude.gov.br/images/...

Prais-Winsten regression was used to analyze the prevalence trend, considering time series autocorrelation.¹⁹19. Wooldridge JM. Introductory econometrics: a modern approach. 7th ed. Florence: South Western College Publishing; 2019. 816 p. Annual percentage change (APC) was classified as rising, stable or falling, as proposed by Antunes.²⁰20. Antunes JLF. Mortalidade por câncer e desigualdade social em São Paulo [tese]. São Paulo: Universidade de São Paulo, Faculdade de Odontologia; 2005. 223 p. For the purpose of this analysis, we used SPSS 24 (IBM SPSS Statistics, 2016). A 5% statistical significance level was set.

The research project was approved by the Universidade Federal do Maranhão Research Ethics Committee, as per Opinion No. 2.965.606, issued on October 17, 2018.

RESULTS

A total of 4,082 leprosy cases were notified, of which 30 were excluded due to duplicity and 23 due to diagnostic errors, totaling 4,029 cases included in the study.

The spatial distribution of leprosy in the region in question was considered heterogeneous, non-random, with prevalence ranging from 2.0/10,000 inhab., in Lajeado Novo, to 11.5/10,000 inhab., in Governador Edson Lobão. The municipalities of Lajeado Novo, São João do Paraíso, Montes Altos, Buritirana, Sítio Novo and Estreito were classified as having medium endemicity, while Campestre, Carolina, Amarante do Maranhão, Porto Franco, João Lisboa and Ribamar Fiquene were classified as having high endemicity, and Davinópolis, Imperatriz, Senador La Rocque and Governador Edson Lobão were classified as having very high endemicity (Figure 2).

Table 1 shows the leprosy prevalence trend in the scenario studied. Overall, the region showed a falling trend (p-value < 0.05), with -61.1 APC over the study period. The highest overall prevalence for the Imperatriz Regional Health Management Unit was 16.2 cases/10,000 inhab. in 2011. The municipalities that showed a falling trend were Buritirana, Davinópolis, Governador Edson Lobão and Imperatriz. The trend was stable in the remaining municipalities in the period. The annual municipal prevalence ranged from 0.0/10,000 inhab., in São João do Paraíso (2008), to 23.5/10,000 inhab., in Governor Edson Lobão (2009).

DISCUSSION

Leprosy showed heterogeneous spatial distribution and a falling prevalence trend in the region we studied. This points, initially, to the fact that leprosy is a neglected disease, and that in this region, which is marked by social inequalities, there are barriers to access to health services, adequate follow-up, early diagnosis and treatment.⁶6. Paz WS, Souza MR, Tavares DS, Jesus AR, Santos AD, Carmo RF, et al. Impact of the covid-19 pandemic on the diagnosis of leprosy in brazil: an ecological and population-based study. Lancet Reg Health Am. 2022;9:100181. doi: 10.1016/j.lana.2021.100181
https://doi.org/10.1016/j.lana.2021.1001... ^,1212. Anchieta JJS, Costa LMM, Campos LC, Viera MR, Mota OS, Morais Neto OL, et al. Análise de tendência dos indicadores de hanseníase em um estado brasileiro hiperendêmico, 2001-2015. Rev Saude Publica. 2019;53:61. doi: 10.11606/S1518-8787.2019053000752
https://doi.org/10.11606/S1518-8787.2019... Generally speaking, health systems have failed to cope with leprosy due to using a disease-centered care model, without considering the social conditions in which people find themselves.²¹21. Sousa ACM, Brandão OS, Duarte NIG, organizadores. Hanseníase: direitos humanos, saúde e cidadania. Porto Alegre: Rede Unida; 2020. 516 p. (Série interlocuções: práticas, experiências e pesquisas em saúde).

Based on the spatial distribution of leprosy prevalence in the municipalities within the UGRSI, the highest prevalence were found to have occurred in Governador Edson Lobão, Senador La Rocque, Imperatriz and Davinópolis, these being places where endemicity was classified as being very high, and Amarante, Carolina and Ribamar Fiquene were classified as having high endemicity. The economic and social vulnerability present in these municipalities²¹21. Sousa ACM, Brandão OS, Duarte NIG, organizadores. Hanseníase: direitos humanos, saúde e cidadania. Porto Alegre: Rede Unida; 2020. 516 p. (Série interlocuções: práticas, experiências e pesquisas em saúde). contributes to this finding. These are municipalities that need special attention from the health sectors, aimed at expanding disease control and surveillance actions.

Imperatriz, where the UGRSI headquarters is located, is among the municipalities with very high endemicity. An investigation carried out regarding the same ten-year period indicated out that 2,468 leprosy cases were recorded in Imperatriz, and that the spatio-temporal risk areas were associated with high population density and intense social disparities.²²22. Lopes FC, Sousa GGS, Silva WM, Costa ACPJ, Santos FS, Pascoal LM, et al. Análise espaço-temporal da hanseníase em município do Nordeste brasileiro prioritário para o controle da doença. Rev Bras Enferm. 2021;74(3):e20201101. doi: 10.1590/0034-7167-2020-1101
https://doi.org/10.1590/0034-7167-2020-1...

The municipality of Buritirana was considered to have medium endemicity, and it should be noted that it borders cities municipalities such as Davinópolis and Senador Larroque, both of which have high leprosy endemicity. It is possible that cases of endemicity considerably lower than those of adjacent municipalities, as in this case, occur due to underreporting and low diagnostic capacity, whereby some residents travel to find health care in nearby municipalities.

The overall prevalence showed a falling trend, which may be indicative of a reduction in leprosy in Maranhão. However, this may also be related to case underreporting. An ecological study identified that in Brazil and in the state of Maranhão in particular, between 2007 and 2015, there were 33,252 and 3,660 underreported leprosy cases, respectively.²³23. Oliveira GL, Oliveira JF, Pescarini JM, Andrade RFS, Nery JS, Ichihara MY, et al. Estimating underreporting of leprosy in Brazil using a Bayesian approach. PLoS Negl Trop Dis. 2021;15(8):e0009700. doi: 10.1371/journal.pntd.0009700
https://doi.org/10.1371/journal.pntd.000...

Another study also conducted in the state of Maranhão, between 2002 and 2011, showed that leprosy prevalence fell in the first eight years analyzed, but then rose until the end of the period. Despite the initial fall, this indicator was considered to be above acceptable, revealing health service strategy weaknesses regarding implementation of a more efficient control and prevention model.²⁴24. Passos CEC, Silva AR, Gonçalves EGR, Neiva FGC, Monteiro SG. Hanseníase no estado do Maranhão: análise das estratégias de controle e os impactos nos indicadores epidemiológicos. Hygeia. 2016;(22):88-100. doi: 10.14393/Hygeia1230888
https://doi.org/10.14393/Hygeia1230888...

With regard to our study, despite not having investigated the programmatic performance indicators of leprosy in the municipalities within the UGRSI which had a falling prevalence trend, and also considering the incipience of studies of this nature carried out in these scenarios, it is assumed that those municipalities have in common significant progress arising from early diagnosis, increased adherence to treatment and expansion of health education actions. On the other hand, municipalities with a stable prevalence trend indicate that leprosy continues to be endemic and reveal possibly weakened health systems and services, with regard to leprosy control actions targeting vulnerable populations.¹²12. Anchieta JJS, Costa LMM, Campos LC, Viera MR, Mota OS, Morais Neto OL, et al. Análise de tendência dos indicadores de hanseníase em um estado brasileiro hiperendêmico, 2001-2015. Rev Saude Publica. 2019;53:61. doi: 10.11606/S1518-8787.2019053000752
https://doi.org/10.11606/S1518-8787.2019...

As for the leprosy endemicity pattern, the geographic areas within the UGRSI considered to be of very high endemicity, with emphasis on the municipalities of Governador Edson Lobão, Senador La Rocque, Imperatriz and Davinópolis, have areas that are devoid and/or deficient in terms of basic sanitation and proper waste disposal, as well as environments with high demographic density, which contribute to the maintenance of the pathogen transmission chain and are positively correlated with higher leprosy prevalence.²⁵25. Gonçalves JRS, Albuquerque FLS, Rosário LCV, Araujo MN, Waquim SJB, Santana TCFS, et al. Perfil epidemiológico e clínico da Hanseníase no estado do Maranhão no período de 2008 a 2017. Brazilian Journal of Health Review. 2021;4(4):17015-27. doi: 10.34119/bjhrv4n4-207
https://doi.org/10.34119/bjhrv4n4-207... ^,2626. Gregório V, Pedroza D, Barbosa C, Bezerra G, Montarroyos U, Bonfim C, et al. Prevendo a detecção da lepra em uma área hiperendêmica do Brasil: usando a análise de séries cronológicas. Indian J Dermatol Venereol Leprol. 2021;87:651-9. doi: 10.25259/ijdvl_1082_19
https://doi.org/10.25259/ijdvl_1082_19...

Based on data from the coverage report on Primary Care and the Family Health Strategy in the state of Maranhão,²⁷27. Ministério da Saúde (BR). Relatórios e histórico de cobertura de atenção básica e estratégia saúde da família no Estado do Maranhão. Brasília: Ministério da Saúde ; 2018 [citado 2022 Abr 23]. Disponível em: Disponível em: https://egestorab.saude.gov.br/paginas/acessoPublico/relatorios/relHistoricoCoberturaAB.xxhtm
https://egestorab.saude.gov.br/paginas/a... we found that higher leprosy prevalence were detected in municipalities with lower Family Health Strategy coverage. As such, Primary Health Care needs to be strengthened through training health professionals, so as to favor early diagnosis and reduce leprosy transmission.

The limitations of this study consisted of the use of secondary data, and there may be underreporting of leprosy cases. As such, we consider that leprosy prevalence we found may be underestimated.

The conclusion reached is that the spatial distribution of leprosy was heterogeneous, and its prevalence trend was falling. Thus, the need emerges to plan and implement health actions targeting vulnerable populations, such as tracing and early detection of new cases, active searching for health care dropout cases and intensification of health education, aiming at effective adherence to treatment.

REFERENCES

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