Figure 1.
Slum community site in the city of Salvador, Brazil.
(A) The yellow line in the aerial photograph is the boundary of the study site in the Pau da Lima community. The map in the bottom left corner shows the location of Salvador in Brazil and the study site (red) within the city. (B) Photograph of the typical environment at the community study site, which shows a valley in which households is situated and the proximity of households to open sewers and refuse. (C) Close-up view of the orthomap used to georeference households (red and black dots) and environmental attributes, such as open sewers (blue line) and refuse deposits, for the region marked as a yellow box in Panel A. The red arrow represents the direction from which the photograph in Panel B was taken.
Figure 2.
Distribution of reciprocal microscopic agglutination test titers for 3,171 subjects from the slum community site.
Labels above the bars indicate the number of subjects (% of total), according to their highest reciprocal titer. The open bar represents seronegative subjects. Subjects with highest reciprocal titres against L. interrogans serovar Copenhageni, multiple serovars and serovars other than Copenhageni are shown as black bars, grey bars and crosshatched bars, respectively.
Table 1.
Risk factors for Leptospira antibodies among subjects at the slum community site.
Figure 3.
Spatial distribution of subjects with Leptospira antibodies and all enrolled subjects, according to place of residence, and environmental attributes of the community site.
Panels A and B show the smoothed Kernel density distribution of subjects with Leptospira antibodies (N = 489) and all (N = 3,171) subjects, respectively, according to place of residence. The yellow-to-red gradient represents increasing density in smoothing analyses which used 40 meters as the bandwidth. Black circles show the location of subject households. Panel C shows the distribution of the population-adjusted Kernel density estimator for subjects with Leptospira antibodies which was calculated as the ratio of the estimators for subjects with Leptospira antibodies and all subjects. Panel D shows a topographic map generated by the digital terrain model. The yellow line is the level that is 20 meters above the lowest point in the four valleys within the community site. Panels E and F show the distribution of, respectively, open rainwater and sewage drainage systems and accumulated refuse according to size (m2).
Figure 4.
Generalized additive models (GAM) of the association between the risk of acquiring Leptospira antibodies and continuous variables of (A) per capita daily household income, (B) level of household in meters above the lowest point in valley, and (C) distance in meters to the nearest open sewer, and (D) reported number of rats sighted in the household environment.
The coefficient, f(infection), in the GAM model is a measure for the risk of acquiring Leptospira antibodies. In Panels A, B, C and D, the x axis intercept values, where f(infection) equals zero, were US$1.70/day, 22 meters, 22 meters and 2 rats, respectively.