Diarrheal Mortality of Children in Association with Hydrography in Brazil

Is the pattern of childhood mortality due to diarrhea related to hydrography? To answer this kind of question we describe a method to examine associations between peak time of mortality from diarrhea in children less than 5 years for the period 1979-89 and relative location along the hydrologic regime of 8 major hydrographic regions in Brazil. In order to better understand the underlying heterogeneity found in mortality peak timing patterns a multiscale approach is used. Continuous geostatistical surfaces of mortality peak timing are created and validated based on these different spatial scales. We extract “mortality peak timing profiles” along the main streams within Brazil and test for possible trends in this peak timing variable in stream flow direction. Some first results demonstrate that there is a dominant trend of increasing mortality peak timing values downstream for most of the hydrographic regions. There are considerable differences between the spatial scales due to the higher degree of heterogeneity in peak timing at finer spatial scales, which remains hidden at coarser spatial scales. We found some deviations in the explored trends, which are possibly caused by a lack of underlying data and thus higher uncertainty in the underlying geostatistical model. Two hydrographic regions even show a trend into the opposite direction, upstream. Our approach allows for the formulation of interesting hypotheses regarding the capture of regional dynamics of diarrheal disease within various hydrographic regions. However, further research and refinement of assumptions is needed to improve this approach. One distinct advantage of the proposed approach is that the results are robust against effects of regional variation and non-linearity of relationships. * Corresponding author. Address all inquiry to Stefan Leyk [email protected]