IJE Advance Access originally published online on April 27, 2006
International Journal of Epidemiology 2006 35(4):994-1000; doi:10.1093/ije/dyl072
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Article |
Socioeconomic, environmental, and behavioural risk factors for leprosy in North-east Brazil: results of a case–control study
1 Departamento de Saúde Comunitária, Faculdade de Medicina, Universidade Federal do Ceará, R: Prof. Costa Mendes, 1608-5o Andar, CEP 60431-140 Fortaleza, CE, Brazil.
2 Instituto de Saúde Coletiva, Rua Padre Feijó, 29, Canela, CEP: 40110-170 Salvador, BA, Brazil.
3 Department Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Room 258b, London WC1E 7HT, UK.
4 Institute for Infectious Medicine, Charité-University Medicine Berlin, Campus Benjamin Franklin, Hindenburgdamm 27, D-12203 Berlin, Germany.
* Corresponding author. E-mail: ligia{at}ufc.br
Background Brazil reports almost 80% of all leprosy cases in the Americas. This study aimed to identify socioeconomic, environmental, and behavioural factors associated with risk of leprosy occurrence in the endemic North-eastern region.
Methods A case–control study in four municipalities. Cases: cases of leprosy diagnosed in the previous 2 years, with no other known, current, or past case of leprosy in the household or in the neighbourhood. Controls: individuals presenting for reasons other than skin problems to the health unit where the case was diagnosed and who lived in the same municipality as the case with whom it was matched. For each case four controls were selected. A semi-structured questionnaire was used to collect demographic, socioeconomic, environmental, and behavioural data. A multivariate hierarchical analysis was performed according to a previously defined framework.
Results 226 cases and 857 controls were examined. Low education level, ever having experienced food shortage, bathing weekly in open water bodies (creek, river and/or lake) 10 years previously, and a low frequency of changing bed linen or hammock (
biweekly) currently were all significantly associated with leprosy. Having a BCG vaccination scar was found to be a highly significant protective factor.
Conclusions Except for BCG vaccination, variables that remained significant in the hierarchical analysis are cultural or linked to poverty. They may act on different levels of the transmission of Mycobacterium leprae and/or the progress from infection to disease. These findings give credit to the hypothesis that person-to-person is not the only form of M. leprae transmission, and that indirect transmission might occur, and other reservoirs should exist outside the human body.
Keywords Leprosy, epidemiology, risk-factors, behavioural, environmental, socioeconomic-cultural, North-east Brazil
Accepted 16 March 2006