A case-control study of microenvironmental risk factors for urban visceral leishmaniasis in a large city in Brazil, 1999-2000

Objectives. We investigated potential microenvironmental risk factors for visceral leishmaniasis in urban and suburban areas, and developed risk scores to characterize the household and the neighborhood. These scores may be useful to identify microenvironments within cities that place residents at greater risk of visceral leishmaniasis. Methods. In this case-control study, cases were all persons with visceral leishmaniasis reported from July 1999 through December 2000 in the Belo Horizonte metropolitan area, Brazil. Two kinds of controls-neighborhood and hospital-were used. Cases and controls were matched by age (+/- 2 years). We developed four scores to characterize the microenvironment (indoor, outdoor, animal indoor, and animal outdoor), and also considered the level of urbanization of the area. Results. A total of 106 neighborhood controls and 60 hospital controls were identified for 109 cases. Among the cases, 69 (63.3%) were men and 40 (36.7%) were women. Most cases were under 15 years old (64.2%), and 39 (35.8%) were 15 years old or more. The outdoor score [odds ratio (OR) = 1.49; 95% confidence interval (CI) = 1.03-2.14] and animal outdoor scores (OR = 1.79[95% CI 1.21-2.65]) were significantly associated with the odds of visceral leishmaniasis in our sample. We also found a significant interaction between sex and age. Compared to females 15 years old or more, males 15 years old or more were more likely to have visceral leishmaniasis (OR = 7.02[95% CI 2.20-22.20]). Conclusions. Animals in the neighborhood were associated with a greater odds of visceral leishmaniasis. Cases were more likely than controls to live in transitional or rural areas, although this difference was not statistically significant, possibly because of the small sample size.