Malaria Risk Drivers in the Brazilian Amazon: Land Use-Land Cover Interactions and Biological Diversity

Abstract

Malaria is a prevalent disease in several tropical and subtropical regions, including Brazil, where it remains a significant public health concern. Even though there have been substantial efforts to decrease the number of cases, the reoccurrence of epidemics in regions that have been free of cases for many years presents a significant challenge. Due to the multifaceted factors that influence the spread of malaria, influencing malaria risk factors were analyzed through regional outbreak cluster analysis and spatio-temporal models in the Brazilian Amazon, incorporating climate, land use/cover interactions, species richness, and number of endemic birds and amphibians. Results showed that high amphibian and bird richness and endemism correlated with a reduction in malaria risk. The presence of forest had a risk-increasing effect, but it depended on its juxtaposition with anthropic land uses. Biodiversity and landscape composition, rather than forest formation presence alone, modulated malaria risk in the period. Areas with low endemic species diversity and high human activity, predominantly anthropogenic landscapes, posed high malaria risk. This study underscores the importance of considering the broader ecological context in malaria control efforts.

Keywords: Amazon biome; INLA; biological diversity; bird and amphibian richness-endemics; land use/cover interactions; landscape composition; malaria; spatio-temporal modeling.

Figure 1

The (left) and (center) column shows LULC percentage change (%) during the period 2007–2018 at the municipality level; the negative values represent a decrease, and positive values represent an increase in the land use–land cover area of each covariate. The (right) column shows the average species richness maps at the municipality level.

Figure 2

Coefficient plots of posterior distributions effect sizes with the median (dark blue and green lines) and 95% credible intervals (light blue and green shades) of each covariate for (A) Plasmodium vivax cases in blue and (B) Plasmodium falciparum cases in green; the significant effects are represented in boldface and marked with an asterisk.

Figure 3

INLA median effect on the credible intervals in the P. vivax risk based on the LULC interaction model (100 km² mesh maps). Lower value cells (blue) and higher values cells (red) are based on the landscape configuration (see Supplementary Materials) for all years (2007–2018).