Abstracts

Background

Leprosy remains a public health problem in endemic pockets among several countries throughout the world, including Brazil. Migration has been identified as one of the social determinants that can influence health and risk for neglected tropical diseases (NTDs) ¹1 . World Health Organization. Closing the gap in a generation: health equity through action on the social determinants of health. Geneva: World Health Organization; 2008. ^{, 2}2 . Aagaard-Hansen J, Chaignat CL. Neglected tropical diseases: equity and social determinants. In: Blas E, Kurup AS, editors. Equity social determinants and public health programmes. Geneva: World Health Organization; 2010. p. 135-57., and is considered a possible factor in leprosy susceptibility and distribution in Brazil ³3 . Magalhães MCC, Rojas LI. Diferenciação territorial da hanseníase no Brasil. Epidemiol Serv Saúde 2007; 16:75-84. ^{, 4}4 . Kerr-Pontes LRS, Montenegro ACD, Barreto ML, Werneck GL, Feldmeier H. Inequality and leprosy in Northeast Brazil: an ecological study. Int J Epidemiol 2004; 33:262-9.. Other neglected diseases have also been associated with population movement, including leishmaniasis ⁵5 . Aagaard-Hansen J, Nombela N, Alvar J. Population movement: a key factor in the epidemiology of neglected tropical diseases. Trop Med Int Health 2010; 15:1281-8. ^{, 6}6 . Costa CH, Pereira HE, Araujo MV. Visceral leishmaniasis epidemic in Piaui state Brazil 1980-1986. Rev Saúde Pública 1990; 24:361-72. schistosomiasis ⁷7 . Watts S. The social determinants of schistosomiasis. http://www.tropikanet/review/051114-Schistosomiasis_Social_Determinants/article.pdf (accessed on 23/Jan/2011).
http://www.tropikanet/review/051114-Schi... ^{, 8}8 . Ximenes R, Southgate B, Smith P, Neto L. Migration and urban schistosomiasis the case of Sao Lourenco da Mata Northeast of Brazil. Rev Inst Med Trop São Paulo 2000; 42:209-17. ^{, 9}9 . Kloos H, Correa-Oliveira R, dos Reis DC, Rodriques EW, Monteiro LAS, Gazzinelli A. The role of population movement in the epidemiology and control of schistosomiasis in Brazil: a preliminary typology of population movement. Mem Inst Oswaldo Cruz 2010; 105:578-86., and Chagas disease ¹⁰10 . Drumond J, Marcopito L. Migração interna e a distribuição da mortalidade por doença de Chagas, Brasil, 1981/1998. Cad Saúde Pública 2006; 22:2131-40.. Migration can increase the risk of NTD transmission and susceptibility, as non-immune migrants move into areas of NTD endemicity, and infected migrants may return to non-endemic areas through circular migration or permanent movement ⁵5 . Aagaard-Hansen J, Nombela N, Alvar J. Population movement: a key factor in the epidemiology of neglected tropical diseases. Trop Med Int Health 2010; 15:1281-8. ^{, 7}7 . Watts S. The social determinants of schistosomiasis. http://www.tropikanet/review/051114-Schistosomiasis_Social_Determinants/article.pdf (accessed on 23/Jan/2011).
http://www.tropikanet/review/051114-Schi... .

There are many reasons for migration: employment opportunities and access to better infrastructure, such as healthcare and education, can attract migrants from other areas ¹¹11 . United Nations Development Program. Mobility and migration. A guidance note for human development report teams. New York: United Nations Development Program; 2010. ^{, 12}12 . Rayp G, Ruyssen I. Africa on the move: an extended gravity model of intra-regional migration. In: Migration, a world in motion: a multinational conference on migration and migration policy. Maastricht: Association for Public Policy Analysis and Management Netherlands; 2010. http://umdcipe.org/conferences/Maastricht/conf_papers/Papers/Africa_on_the_Move.pdf (accessed on 17/May/2011).
http://umdcipe.org/conferences/Maastrich... ; while the socioeconomic environment, including poor job opportunities and low wages ¹²12 . Rayp G, Ruyssen I. Africa on the move: an extended gravity model of intra-regional migration. In: Migration, a world in motion: a multinational conference on migration and migration policy. Maastricht: Association for Public Policy Analysis and Management Netherlands; 2010. http://umdcipe.org/conferences/Maastricht/conf_papers/Papers/Africa_on_the_Move.pdf (accessed on 17/May/2011).
http://umdcipe.org/conferences/Maastrich... ^{, 13}13 . International Organization for Migration. World migration 2008: managing labour mobility in the evolving global economy. v. 4. Geneva: International Organization for Migration; 2008. (IOM World Migration Report Series). ^{, 14}14 . Ackah C, Medvedev D. Internal migration in Ghana: determinants and welfare impacts. Washington DC: World Bank/West Africa Poverty Reduction and Economic Management Unit; 2010. (World Bank Policy Research Working Paper Series, 5273). ^{, 15}15 . Golgher A, Rosa CH, Araujo Jr. AF. The determinants of migration in Brazil. In: Proceedings of the 33th Brazilian Economics Meeting. Niterói: Associação Nacional dos Centros de Pós-graduação em Economia; 2005. p. 1-20. influence the decision to migrate from the place of origin. This is especially reflected in rural to urban population movement. In Brazil, migration has historically been stimulated by strong disparities between poor rural areas in the northeast of the country and large urban centers, a pattern typical of migration flow throughout Latin America ¹⁶16 . Deshingkar P, Grimm S. Internal migration and development: a global perspective. Geneva: International Organization for Migration; 2005. (IOM Migration Research Series).. Recently, there has been a shift in migration dynamics toward rural in-migra- tion ¹⁷17 . Golgher A, Rosa CH, Araujo Jr. AF. Determinants of migration in Brazil: regional polarization and poverty traps. Papeles de Población 2008; 56:135-71. resulting from opportunities in civil development projects and agricultural expansion. National policies and regional economic disparities and conditions can influence the direction and duration of migration ⁵5 . Aagaard-Hansen J, Nombela N, Alvar J. Population movement: a key factor in the epidemiology of neglected tropical diseases. Trop Med Int Health 2010; 15:1281-8., and temporary or circular patterns ¹⁸18 . DeWind J, Holdaway J. Internal and international migration and development: research and policy perspectives. In: DeWind J, Holdaway J, editors. Migration and development within and across borders: research and policy perspectives on internal and international migration. Geneva: International Organization for Migration/Social Science Research Council; 2008. p. 15-26. ^{, 19}19 . Beguy D, Bocquier P, Zulu EM. Circular migration patterns and determinants in Nairobi slum settlements. Demographic Research 2010; 23:549-86. ^{, 20}20 . Deshingkar P. Circular internal migration and development in India. In: DeWind J, Holdaway J, editors. Migration and development within and across borders: research and policy perspectives on internal and international migration. Geneva: International Organization for Migration/Social Science Research Council; 2008. p. 161-87..

A complex relationship exists where low socioeconomic status and poor education influence job skills and employment options, creating urgency for movement, particularly to urban areas creating uncontrolled growth around city perimeters. Poverty and biological vulnerability converge in crowded and substandard housing in areas lacking basic sanitary conditions, access to clean water and other utilities, factors that are also associated with leprosy transmission ⁴4 . Kerr-Pontes LRS, Montenegro ACD, Barreto ML, Werneck GL, Feldmeier H. Inequality and leprosy in Northeast Brazil: an ecological study. Int J Epidemiol 2004; 33:262-9. ^{, 21}21 . Kerr-Pontes LRS, Barreto M, Evangelista C, Rodrigues L, Heukelbach J, Feldmeier H. Socioeconomic environmental and behavioral risk factors for leprosy in North-east Brazil: results of a case-control study. Int J Epidemiol 2006; 35:994-1000. ^{, 22}22 . Sales AM, Leon AP, Duppre NC, Hacker MA, Nery JA, Sarno EN, et al. Leprosy among patient contacts: a multilevel study of risk factors. PLoS Negl Trop Dis 2011; 5:e1013.. These crowded living conditions that include close proximity to individuals with leprosy, particularly multibacillary leprosy, increase the risk of infection in comparison to other social contacts ²²22 . Sales AM, Leon AP, Duppre NC, Hacker MA, Nery JA, Sarno EN, et al. Leprosy among patient contacts: a multilevel study of risk factors. PLoS Negl Trop Dis 2011; 5:e1013. ^{, 23}23 . Fine P, Sterne J, Ponninghaus J, Bliss L, Saul J, Chihuana A, et al. Household and dwelling contact as risk factors for leprosy in Northern Malawi. Am J Epidemiol 1997; 146:91-102. ^{, 24}24 . Richardus JH, Meima A, van Marrewijk C, Croft RP, Smith TC. Close contacts with leprosy in newly diagnosed leprosy patients in a high and low endemic area: comparison between Bangladesh and Thailand. Int J Lepr Other Mycobact Dis 2005; 73:249-57.. In Brazil, household contact monitoring is part of the national leprosy surveillance strategy, as is monitoring leprosy among children as an indicator of ongoing active transmission ²⁵25 . Ministério da Saúde. Portaria no 3.125, de 7 de Outubro de 2010. Aprova as diretrizes para vigilância, atenção e controle da hanseníase. http://portal.saude.gov.br/portal/arquivo/pdf/portaria_n_3125_hanseniase_2010.pdf (accessed on 05/Jun/2013).
http://portal.saude.gov.br/portal/arquiv... .

Understanding leprosy transmission dynamics is important for insight into how population movement complicates disease control ⁵5 . Aagaard-Hansen J, Nombela N, Alvar J. Population movement: a key factor in the epidemiology of neglected tropical diseases. Trop Med Int Health 2010; 15:1281-8. ^{, 7}7 . Watts S. The social determinants of schistosomiasis. http://www.tropikanet/review/051114-Schistosomiasis_Social_Determinants/article.pdf (accessed on 23/Jan/2011).
http://www.tropikanet/review/051114-Schi... . As World Health Organization (WHO) strategies increasingly move toward greater control and elimination of NTDs, a focused examination of factors associated with migration in those affected by the disease is necessary to better integrate interventions aimed at disease control and elimination. This study has the goal of supporting the Brazil Ministry of Health Leprosy Control Programs in providing services for migrating populations. The study was designed with the objective of identifying demographic, socioeconomic, health-service related and clinical factors associated with migration before and after diagnosis with leprosy in an affected population.

Methods

Study design

This cross-sectional study was designed as operational research to provide evidence for improvement to the national and state leprosy control programs. All municipalities included are located in a major endemic cluster identified by the Brazilian Ministry of Health as high-risk areas for leprosy ²⁶26 . Penna MLF, Gross MAF, Rocha MCN, Penna GO. Comportamento epidemiológico da hanseníase no Brasil. In: Secretaria de Vigilância em Saúde, Ministério da Saúde, organizador. Saúde Brasil 2009: uma análise da situação de saúde e da agenda nacional e internacional de prioridades em saúde. Brasilia: Ministério da Saúde; 2010. p. 295-318..

Study area and population

Tocantins, the newest Brazilian state located in the north region, is a leprosy hyperendemic area with the highest incidence in Brazil – 88.54/100,000 inhabitants in 2009 (Health Informatics Department. http://tabnet.datasus.gov.br/cgi/deftohtm.exe?idb2011/d0206.def, accessed on 10/Apr/2011). With one of the fastest growing agriculture-based economies, Tocantins attracts labor migration with more than one third of the population coming from a different state and more than one half born in different municipalities ²⁷27 . Instituto Brasileiro de Geografia e Estatística. Pesquisa Nacional por Amostra de Domicílios, 2007. http://www.ibge.gov.br (accessed on 29/Sep/2010).
http://www.ibge.gov.br... ^{, 28}28 . Instituto Brasileiro de Geografia e Estatística. Pesquisa Nacional por Amostra de Domicílios, 2008. http://www.ibge.gov.br (accessed on 29/Sep/2010).
http://www.ibge.gov.br... .

The target population included all new leprosy cases diagnosed between 2006 and 2008, who were living in endemic municipalities. Individuals living outside of the cluster, those with mental illness or other characteristics that hindered interviews were excluded. Relapsed leprosy cases and those who died after diagnosis were also not included.

Data collection

Municipality Health Secretariats were informed by the Tocantins State Health Department about the study and field visits were coordinated for data collection. The study population was identified through the database of the National Information System for Notifiable Diseases (SINAN). Patients were invited through Community Health Agents to participate in the study and to be interviewed at the local health care center. Home visits accompanied by local Community Health Agents were performed when individuals did not present at the health care center.

Data collection was conducted between September and December 2009. Clinical data were collected from patients’ charts. All other variables, including information on migration, were investigated by interview using structured questionnaires. Data collection forms were composed of six groups of variables, and information on migration itself: (1) Socio-demographics (sex, age, marital status, education, employment); (2) Housing/Economic variables (household density, household income, area of residence, utility access; (3) Disease-related variables (clinical form of the disease, operational classification, grade of disability at diagnosis); (4) Health services variables (visits by community health worker, access to health services); (5) Migration variables (length of time at residence, migration before and after diagnosis); and (6) Attitudes and reported practices regarding leprosy and its cure. For detailed information on migration, study participants were asked for the municipality and state of their birth, where they had lived during the five years prior to diagnosis, and whether they had moved after diagnosis.

Data analysis

Bivariate analysis using Fisher’s exact test was conducted whereby socio-demographic, economic, clinical, health service-related and attitudes/practices variables were compared between migrants with leprosy and non-migrant residents with leprosy (Table 1). These variables were investigated for their association with three different (migration) outcome variables: (1) migration after birth, defined as municipality of birth different from current municipality of residence; (2) migration during five years prior to leprosy diagnosis; and (3) migration after diagnosis. Migration after birth provided a baseline for any lifetime migration, while migration before diagnosis was limited to the average five year latency period for leprosy onset, which is also the current standard in the Brazilian Census survey and reduces recall bias in the survey. As migrant multi-stage migration was also considered, we allowed for non-exclusivity between the three migration outcomes being investigated in the bivariate analysis.

Odds ratios and their respective 95% confidence intervals (95%CI) were calculated. Theoretically meaningful confounders (age, income, gender and education) were investigated in the bivariate analysis by determining their association (p < 0.05) with the three migration variables. Only age was a potential confounder. Income was not associated with the three migration outcomes and education was no longer significant among birth migrants after controlling for age. As internal migration is equally distributed between males and females in Brazil ²⁹29 . Instituto Brasileiro de Geografia e Estatística. Censo populacional 2010. Resultados. http://censo2010.ibge.gov.br/ (accessed on 06/Nov/2011).
http://censo2010.ibge.gov.br/... , and the sample is also equally distributed between males and females, gender was not believed to present confounding. Additionally, only one of the migration outcomes in the bivariate analysis was significantly associated with gender.

A separate multivariate logistic regression analysis was conducted for each variable found to be significant in bivariate analysis with a p-value < 0.05 controlling for age. Adjusted odds ratios for the association of migration before diagnosis and after diagnosis migration outcomes compared to non-migrant residents were calculated.

Data were entered twice, using Epi Info software version 3.5.1 (Centers for Disease Control and Prevention, Atlanta, USA) and cross-checked for entry-related errors. Shapiro-Wilk test and histograms were used to assess normality. Data analysis was conducted using Stata version 11 (Stata Corp., College Station, USA).

Ethics

The study was approved by the Ethics Research Committee of the Federal University of Ceará (Fortaleza, Brazil) and by the Ethics Research Committee of Lutheran University of Palmas (Palmas, Brazil). Permission to perform the study was also obtained by the Tocantins State Health Secretariat, the State Leprosy Control Program and the municipalities involved. Informed written consent was obtained from study participants after explaining the objectives of the study. To avoid any harm, strict confidentiality was kept, and the diagnosis was not revealed to others, including family members. Interviews were conducted in private. In the case of minors, consent was obtained from a guardian.

Results

The sample was selected from 2,160 individuals diagnosed with leprosy between 2006 and 2008. A total of 1,074 individuals from 79 municipalities were included in the analysis. One municipality did not diagnose any cases of leprosy during the study period, and three municipalities had few cases (n = 12) which were not included due to non-consent or because they could not be located. Of those who were not interviewed, 11 were not confirmed leprosy cases, were unable to attend due to illness/hospitalization, inebriation or incarceration (n = 15), could not be located at the given address (n = 35), were not known at the healthcare center (n = 23), lived in a remote area (n = 23), moved after diagnosis (n = 269), or were otherwise not at home/working/traveling (n = 469). Despite multiple attempts, some did not attend the scheduled interviews (n = 210) and 31 refused to participate. These individuals were excluded from the study.

Of the total 1,074 individuals, 555 (51.7%) were males and 519 (48.3%) females, ranging in age from 5 to 98 years of age (mean = 41.8 year; standard deviation: 19.01). There were 82 children under 15 (7.6%). Nearly half of the individuals (514; 47.9%) were working at least part time/ in temporary employment, 162 (15.1%) were unemployed, 178 (16.6%) retired and 230 (21.4%) engaged otherwise, most notably as students 127 (11.8%) or housewives 78 (7.3%). About one in five (n = 240, 22.4%) was illiterate and 190 (17.8%) completed a high school education or more. The mean monthly household income was R$ 757 (≈ US$ 440), and nearly one-third (n = 299, 28.5%) were living on less than the minimum monthly wage.

Overall, 426 (42.1%) were classified with multibacillary leprosy at the time of diagnosis, the majority having Grade 0 disability at diagnosis (n = 566, 75.4%), followed by Grade I (n = 155, 20.6%) and Grade II (n = 30, 4.0%). The clinical form of diagnosis was primarily indeterminate (n = 332, 38.3%), followed by borderline (n = 255, 29.5%), tuberculoid (n = 185, 21.4%) and lepromatous leprosy (n = 94, 10.9%).

In terms of migration, 800 (76.2%) individuals interviewed migrated at some point in time after birth; 179 (16.7%) were migrants in the five years prior to diagnosis; and 38 (3.6%) migrated after diagnosis. Children also were among those migrating, and comprised 4.5% of those migrating before diagnosis (n = 8) and 8.5% after diagnosis (n = 19). In total, nearly one fifth (n = 199, 18.6%) of those interviewed lived in a different municipality or state five years prior and/or after diagnosis. Migration in the endemic cluster in Tocantins (43.9%, n = 76) and migration residence in other states (45.1%, n = 78) comprised the majority of population movement before diagnosis. Only 17.3% of migrants resided in non-endemic municipalities in Tocantins during the five years prior to diagnosis. After diagnosis, 73.7% moved within Tocantins, 57.9% to endemic areas of the state. 26% of those who migrated after diagnosis moved to other states.

Factors associated with migration in the five years before diagnosis

In bivariate analysis age (30-44), poverty, and residence of 10 years or less were associated with migration before diagnosis with leprosy (Table 1).

Logistic regression, controlling for age, identified poverty and clinical variables associated with migration before diagnosis with leprosy. The migrants were more likely to lack access to electricity, public water, and waste management, all indicators of poverty in Brazil. Migrants were also significantly less likely to live in a brick home compared to non-migrant residents, with significantly less time living in their current place of residence (10 years or less). Migrants before diagnosis were also more likely to have multibacillary form of leprosy compared to non-migrant residents with leprosy (Table 2).

Factors associated with migration after diagnosis

After diagnosis, residence in the current household of five years or less and before diagnosis migration was associated with migration (Table 1).

Migration after diagnosis was associated with key demographic factors after adjusting for age (Table 3). Males were more likely to migrate than females. Also, residence at current household of five years or less and before diagnosis migration was significantly associated with migration.

Discussion

Migration can complicate disease control when infected and susceptible people move between endemic and non-endemic areas. Environmental and social factors can influence migration, while health outcomes can be affected by the conditions at locations where movements take place.

In this study, many socio-demographic, clinical, health service and migration variables were investigated. After adjusting for age, a confounding factor for leprosy and migration, key demographics, poverty, factors associated with migration, and multibacillary form of leprosy remained significant for those who migrated before leprosy diagnosis, while only factors related to migration remained associated after diagnosis. Contrary to our expectations, migrant accounts of health service access and stigma did not appear to be associated with migration, although advanced disease expression indicated a delay in diagnosis.

A culture of migration was observed among those affected by leprosy in Tocantins, with more than three-quarters having migrated at some stage in their lives and nearly one-fifth within the last five years. We also found that after diagnosis migration was significantly associated with prior migration, consistent with findings in other studies ³⁰30 . Hossain MZ. Rural-urban migration in Bangladesh: a micro-level study. In: XXIV International Union for the Scientific Study of Population (IUSSP). General Population Conference, 2001. http://www.archive-iussp.org/Brazil2001/s20/S28_P02_Hossain.pdf (accessed on 19/Aug/2012).
http://www.archive-iussp.org/Brazil2001/... . Migration can additionally place resident populations at risk, and in Brazil migration has been considered as a possible explanation for diseases, such as leishmaniasis, schistosomiasis and Chagas disease, that have moved into previously non-endemic areas ⁵5 . Aagaard-Hansen J, Nombela N, Alvar J. Population movement: a key factor in the epidemiology of neglected tropical diseases. Trop Med Int Health 2010; 15:1281-8. ^{, 7}7 . Watts S. The social determinants of schistosomiasis. http://www.tropikanet/review/051114-Schistosomiasis_Social_Determinants/article.pdf (accessed on 23/Jan/2011).
http://www.tropikanet/review/051114-Schi... ^{, 8}8 . Ximenes R, Southgate B, Smith P, Neto L. Migration and urban schistosomiasis the case of Sao Lourenco da Mata Northeast of Brazil. Rev Inst Med Trop São Paulo 2000; 42:209-17. ^{, 9}9 . Kloos H, Correa-Oliveira R, dos Reis DC, Rodriques EW, Monteiro LAS, Gazzinelli A. The role of population movement in the epidemiology and control of schistosomiasis in Brazil: a preliminary typology of population movement. Mem Inst Oswaldo Cruz 2010; 105:578-86. ^{, 10}10 . Drumond J, Marcopito L. Migração interna e a distribuição da mortalidade por doença de Chagas, Brasil, 1981/1998. Cad Saúde Pública 2006; 22:2131-40.. We found that much of the migration in the five years prior to diagnosis was within the endemic cluster in Tocantins and also other states, primarily neighboring Maranhão and Pará. From Maranhão, migration was largely from Imperatriz, while in Pará State, Conceição do Araguaia and São Geraldo were principal sites of prior residence. These three municipalities are located in hyperendemic areas for leprosy ²⁶26 . Penna MLF, Gross MAF, Rocha MCN, Penna GO. Comportamento epidemiológico da hanseníase no Brasil. In: Secretaria de Vigilância em Saúde, Ministério da Saúde, organizador. Saúde Brasil 2009: uma análise da situação de saúde e da agenda nacional e internacional de prioridades em saúde. Brasilia: Ministério da Saúde; 2010. p. 295-318.. Considerably fewer migrants resided in municipalities in Tocantins outside of the endemic cluster during the five years prior to diagnosis. The majority of after diagnosis migrants moved to other endemic areas in Tocantins. Presence of leprosy among children who migrated highlights active transmission in these regions.

Key demographics

Migration is most often associated with the movement of young adults, typically males between the ages of 20 and 35, who migrate for employment ¹⁴14 . Ackah C, Medvedev D. Internal migration in Ghana: determinants and welfare impacts. Washington DC: World Bank/West Africa Poverty Reduction and Economic Management Unit; 2010. (World Bank Policy Research Working Paper Series, 5273). ^{, 19}19 . Beguy D, Bocquier P, Zulu EM. Circular migration patterns and determinants in Nairobi slum settlements. Demographic Research 2010; 23:549-86. ^{, 30}30 . Hossain MZ. Rural-urban migration in Bangladesh: a micro-level study. In: XXIV International Union for the Scientific Study of Population (IUSSP). General Population Conference, 2001. http://www.archive-iussp.org/Brazil2001/s20/S28_P02_Hossain.pdf (accessed on 19/Aug/2012).
http://www.archive-iussp.org/Brazil2001/... ^{, 31}31 . Barbieri AF, Carr DL, Bilsburrow RE. Migration within the frontier: the second generation colonization in the ecuadorian Amazon. Popul Res Policy Rev 2009; 28:291-320.. We found that migration of leprosy-affected individuals was significantly associated with being male after diagnosis, and overall, migrants were slightly older than the younger age-set typical of migration globally. This age pattern is consistent with population movement in Brazil ¹⁷17 . Golgher A, Rosa CH, Araujo Jr. AF. Determinants of migration in Brazil: regional polarization and poverty traps. Papeles de Población 2008; 56:135-71.. Migration increased with age and dropped only slightly among those aged 60 or older. Migration of the older age groups may be the result of historical population movements in the Northeast region from rural areas to urban centers due to industrialization ³²32 . Fischlowitz E, Engel M. Internal migration in Brazil. International Migration Review 1969; 3:36-46. and periods of severe drought ³³33 . Barbieri A, Domingues E, Queiroz B, Ruiz R, Rigottin J, Carvalo J, et al. Climate change and population migration in Brazil’s Northeast: scenarios for 2025-2050. Popul Environ 2010; 31:344-70.. This trend has continued into recent decades and may be a factor hindering disease control ⁸8 . Ximenes R, Southgate B, Smith P, Neto L. Migration and urban schistosomiasis the case of Sao Lourenco da Mata Northeast of Brazil. Rev Inst Med Trop São Paulo 2000; 42:209-17. ^{, 34}34 . Montenegro A. Werneck G. Kerr-Pontes LRS, Feldmeier H. Spatial analysis of the distribution of leprosy in the state of Ceara Northeast Brazil. Mem Inst Oswaldo Cruz 2004; 99:683-6.. This historic population movement has contributed to poor sanitation and overcrowding in areas of uncontrolled urbanization in Brazil.

Nearly half of those with leprosy were employed regardless of whether they were migrants or non-migrant residents. This indicates that stigma as a result of leprosy does not appear to be a significant factor for securing employment. In a previous study, stigma was also found to be an insignificant factor in changing residence ³⁵35 . Murto C, Ariza L, Oliveira A, Chichava OA, Alencar CH, Silva LFM, et al. Motives and determinants for residence change after leprosy diagnosis central Brazil. Lepr Rev 2012; 83:16-23. and was a minor issue in therapy interruption ³⁶36 . Chichava O, Ariza L, Oliveira A, Ferreira A, Silva L, Barbosa J, et al. Reasons for interrupting multidrug therapy against leprosy. Lepr Rev 2011; 82:78-9..

Poverty

NTDs are known to be associated with low socioeconomic status, often resulting in poor health ²2 . Aagaard-Hansen J, Chaignat CL. Neglected tropical diseases: equity and social determinants. In: Blas E, Kurup AS, editors. Equity social determinants and public health programmes. Geneva: World Health Organization; 2010. p. 135-57.. While migration typically provides an opportunity to lift individuals out of poverty over time ²⁰20 . Deshingkar P. Circular internal migration and development in India. In: DeWind J, Holdaway J, editors. Migration and development within and across borders: research and policy perspectives on internal and international migration. Geneva: International Organization for Migration/Social Science Research Council; 2008. p. 161-87., the initial decision to migrate is often a strategy to mitigate poverty, and migration also supplements income at critical moments ¹⁶16 . Deshingkar P, Grimm S. Internal migration and development: a global perspective. Geneva: International Organization for Migration; 2005. (IOM Migration Research Series). ^{, 18}18 . DeWind J, Holdaway J. Internal and international migration and development: research and policy perspectives. In: DeWind J, Holdaway J, editors. Migration and development within and across borders: research and policy perspectives on internal and international migration. Geneva: International Organization for Migration/Social Science Research Council; 2008. p. 15-26. ^{, 20}20 . Deshingkar P. Circular internal migration and development in India. In: DeWind J, Holdaway J, editors. Migration and development within and across borders: research and policy perspectives on internal and international migration. Geneva: International Organization for Migration/Social Science Research Council; 2008. p. 161-87. ^{, 30}30 . Hossain MZ. Rural-urban migration in Bangladesh: a micro-level study. In: XXIV International Union for the Scientific Study of Population (IUSSP). General Population Conference, 2001. http://www.archive-iussp.org/Brazil2001/s20/S28_P02_Hossain.pdf (accessed on 19/Aug/2012).
http://www.archive-iussp.org/Brazil2001/... . Unfortunately, these decisions can have further repercussions, negatively affecting health as result of poor housing, sanitation and other socio-environmental conditions ²2 . Aagaard-Hansen J, Chaignat CL. Neglected tropical diseases: equity and social determinants. In: Blas E, Kurup AS, editors. Equity social determinants and public health programmes. Geneva: World Health Organization; 2010. p. 135-57. closely associated with poverty.

While low household income was not specifically associated with migration among leprosy-affected individuals in Tocantins, indirect indicators of poverty were associated with migration in this study. This was particularly relevant for those who migrated prior to diagnosis compared to non-migrant residents with leprosy. Absence of trash collection and access to public water, or not living in a house made of brick were all associated with those who migrated in the five years before diagnosis. Previous studies have found that non-migrants typically have a higher socioeconomic status than migrants ³⁷37 . United Nations Development Program. Overcoming barriers: human mobility and development. Human Development Report 2009. New York: United Nations Development Program; 2009. ^{, 38}38 . Perlman JE. Globalization and the urban poor. New York: United Nations University; 2007. (Research Paper, 2007/76).. Thus, migrants and non-migrant residents with leprosy might be exposed to low socioeconomic levels and poor living standards differentially.

Migration after diagnosis had no association with indicators of poverty. Socioeconomic factors influence the initial decision to migrate, and these variables may change once migration has taken place ³⁰30 . Hossain MZ. Rural-urban migration in Bangladesh: a micro-level study. In: XXIV International Union for the Scientific Study of Population (IUSSP). General Population Conference, 2001. http://www.archive-iussp.org/Brazil2001/s20/S28_P02_Hossain.pdf (accessed on 19/Aug/2012).
http://www.archive-iussp.org/Brazil2001/... . Although our study only considered socioeconomic variables and utility access after leprosy diagnosis, access to better amenities, such as electricity, has been associated with a reduction in further migration ¹⁹19 . Beguy D, Bocquier P, Zulu EM. Circular migration patterns and determinants in Nairobi slum settlements. Demographic Research 2010; 23:549-86..

Migration, leprosy and healthcare access

In Brazil, the most prominent form of leprosy is borderline (41.5%), followed by lepromatous (23.2%), tuberculoid (19.6%) and indeterminate (15.6%) leprosy ³⁹39 . Arantes CK, Garcia MLR, Filipe MS, Nardi SMT, Paschoal V. Avaliação dos serviços de saúde em relação ao diagnóstico precoce da hanseníase. Epidemiol Serv Saúde 2010; 19:155-64.. A quarter of leprosy cases in Brazil in 2010 were classified as multibacillary ⁴⁰40 . Ministério da Saúde. Registro ativo: número e percentual, Casos novos de hanseníase: número, coeficiente e percentual, faixa etária, classificação operacional, sexo, grau de incapacidade, contatos examinados, por estados e regiões, Brasil, 2010. http://portal.saude.gov.br/portal/saude/profissional/visualizar_texto.cfm?idtxt=31200 (accessed on 10/Apr/2011).
http://portal.saude.gov.br/portal/saude/... , which includes midborderline, borderline lepromatous, and lepromatous forms of leprosy. In Tocantins, before diagnosis migration was associated with the more severe multibacillary classification. Multibacillary has a high risk of transmission ²³23 . Fine P, Sterne J, Ponninghaus J, Bliss L, Saul J, Chihuana A, et al. Household and dwelling contact as risk factors for leprosy in Northern Malawi. Am J Epidemiol 1997; 146:91-102. ^{, 41}41 . Moet F, Pahan D, Schuring R, Oskam L, Richardus J. Physical distance genetic relationship age and leprosy classification are independent risk factors for leprosy in contacts of patients with leprosy. J Infec Dis 2006; 193:346-53., while paucibacillary forms have a low transmission risk among those in close contact with individuals with leprosy ⁴²42 . Halder A, Mundle M, Bhadra U, Saha B. Role of paucibacillary leprosy in the transmission of disease. Indian J Lepr 2001; 73:11-5.. The odds of multibacillary among before diagnosis migrants were 1.5 times higher than non-migrant residents with leprosy. Access to early diagnosis may in fact be a consideration for this group.

While poor access to health services has been found to be a motivating factor for migration ¹¹11 . United Nations Development Program. Mobility and migration. A guidance note for human development report teams. New York: United Nations Development Program; 2010., our findings show minimal after diagnosis migration. This is perhaps a response to the need to maintain treatment at the place of diagnosis, within primary health care. Another study of the same population found that lifestyle changes (home ownership, family, better living/neighborhood conditions) were the primary reasons for changing residences, with less than 5% moving for the purpose of seeking diagnosis or treatment ³⁵35 . Murto C, Ariza L, Oliveira A, Chichava OA, Alencar CH, Silva LFM, et al. Motives and determinants for residence change after leprosy diagnosis central Brazil. Lepr Rev 2012; 83:16-23.. The decentralization of health services for leprosy diagnosis and treatment to community health centers throughout Brazil has likely played an important role in this regard.

There was no significant difference in the time from symptom onset to diagnosis among migrants in Tocantins compared to non-migrants. While there is some speculation that migrants are less likely to use health facilities ⁴³43 . United Nations Population Fund. The 2004 Vietnam migration survey: migration and health. Hanoi: General Statistics Office, United Nations Population Fund; 2006., other research has shown that availability of health services even among the displaced, has contributed to improved health ⁴⁴44 . World Health Organization. World health report 2000: health systems. Improving performance. Geneva: World Health Organization; 2000.. Health services were sought by up to a fifth of those that migrated prior to diagnosis and by a quarter of those who migrated after diagnosis, yet migrants did not have significantly more difficulty in accessing health centers or community health workers than non-migrants. Despite this positive information, the prevalence of advanced multibacillary leprosy among those who migrated in the five years prior to diagnosis suggests a delay in diagnosis or poor knowledge of symptoms associated with leprosy. Given the progressive evolution of multibacillary leprosy, lack of access to health care and poor attention to infection could occur over multiple movements.

Limitations

Like many other cross-sectional studies, our study is subject to several limitations. First, the cross-sectional design made causal and temporal relationships difficult to establish. Migration may cause certain behaviors/characteristics, and also be caused by these same variables. For this reason, we focused on associations rather than causes in the analysis and discussion of data.

Despite being a population-based study in a hyperendemic area, we only included in-migrants to municipalities. Anyone moving outside of the cluster during the defined study period was excluded, which limited additional knowledge in regards to after diagnosis migration.

This study was performed in 79 municipalities with a broad geographical range. While this increases the representativeness of our findings, approximately 50% of the population could not be reached. Many individuals were not encountered even after multiple home visits or did not attend scheduled interviews. Some individuals moved to another city outside the cluster. Incomplete patients’ charts and subsequent missing data hampered analysis in some cases. Non-participation bias may have played a role. We aimed at reducing bias by rigorously planning field visits and integrating local primary health care professionals and the State and Municipal Leprosy Control Programs during field work for the present study.

A final limitation is that socioeconomic data were collected after migration. Other researchers have noted the difficulty in differentiating between migrant and non-migrant households because socioeconomic factors may influence the decision to migrate, and these same variables may change once migration has taken place ³¹31 . Barbieri AF, Carr DL, Bilsburrow RE. Migration within the frontier: the second generation colonization in the ecuadorian Amazon. Popul Res Policy Rev 2009; 28:291-320.. In addition, current economic conditions do not account for latency in leprosy, which can manifest up to decades after exposure.

Conclusions

This is the first major systematic study exploring migration in leprosy-affected individuals. In this population in a highly endemic area, factors associated with poverty were associated with migration.

Attention to reaching possibly infected and highly mobile populations in Brazil should be a focus to prevent further transmission of the disease and development of disabilities among those infected. This is particularly important in endemic states, with high in- and between- municipality migration, such as Tocantins. Attention to low-income rural areas should take into account difficulties with transportation. Ease of healthcare access provides the opportunity to reduce disability and increase leprosy control.

Newly emerging trends of circular migration provide an opportunity to investigate these patterns and their relationship to disease transmission and migration flow between community of origin and destination and should be considered for future studies.

Acknowledgments

We thank Adriana Cavalcante Ferreira, Suen de Oliveira Santos, the Health Secretariat of Tocantins, the Municipality Health Secretariats and Primary Health Care Centers. We are also grateful to all patients that kindly agreed to participate in the study. Special thanks to Professor Marcel Tanner, Director of the Swiss Tropical and Public Health Institute (SwissTPH) for insightful review and guidance. This publication is part of the MAPATOPI study (an interdisciplinary project providing evidence for improving the Brazilian leprosy control program), co-financed by CNPq and DECIT.

References

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