The health impacts of ENSO in Brazil are associated with the reduction of precipitation in the northeastern and northern regions as well as excess precipitation in the southern region. The most important outcomes are health events directly associated with heavy rainfall and flooding, especially accidents, and indirect, ecologically mediated variations in the incidence of infectious diseases.
Three main methodological issues are discusses in relation to approaches to the study of climate/health linkages: spatial scale problems, confounding (non-climatic) factors and vulnerability. As far as infectious diseases are concerned, the main confounding factors are insecticide spraying for vector control, environmental management and immunization. Other important confounders are human migration and land cover changes (especially for vector borne diseases), such as deforestation. Spatial scale problems relate to the possible lack of correlation between large scale ENSO parameters such as SOI or SST3 and precipitation patterns on a local basis. Vulnerability, usually considered as linked mainly to social-economic and cultural aspects is discussed in its environmental aspects.
To provide a broader reference for the analysis of climate-health linkages the use of the Landscape concept is proposed. This shall be defined basically by a land area, a vulnerable population and a uniform climate pattern. The Landscape approach is used for a comparison of the impacts of ENSO in the northern and northeastern regions of Brazil. The case of the Roraima state in the Amazon is stressed and four main types of health outcomes were identified as a consequence of the environmental and social disruptions caused by droughts during the current and past ENSO episodes:
1- increase in the number of outbreaks of gastrointestinal infections due to the less availability of safe water
2- increase in the incidence of respiratory ailments, especially in children, due to the smoke from forest fires
3- increase in the incidence of malaria following the interruption of control activities in remote areas due to impossibility of the use of small airplanes caused by the dense smog
4 - the emergence of visceral leishmaniasis as an imported disease brought by the migration of infected persons from other drought-stricken regions