Relationship between the colors of the rivers in the Amazon and the incidence of malaria

Background: Malaria is an infection caused by parasites of the genus Plasmodium, which are transmitted to humans via the bite of the female Anopheles mosquito. In Brazil, approximately 99% of malaria cases are concentrated in the Amazon region. Os rios desempenham um papel importante no ciclo de vida da malária, uma vez que o vetor se reproduz em ambiente aquático. The waters of the rivers in the Amazon have distinct chemical characteristics and this prompted us to analyze the influence of the color of the waters of the rivers in the Amazon on the distribution of malaria. Methodology: This study was conducted for a period of seventeen years (2003-2019) in 50 municipalities in the state of Amazonas, Brazil. A generalized linear mixed model was developed to analyze the association of malaria incidence and three types of river color: white, black and mixed. Principal Findings: The results suggest that there is a trend towards a decrease in malaria cases until 2015, with a possible resumption of the incidence of the disease from 2017 onwards, in all types of river color. In addition, the research indicates that places located near black- or mixed-water rivers have a higher incidence of malaria when compared to places on the banks of white-water rivers. Conclusions: Historically, the hydrological regime has played an important role in the dynamics of malaria in the Amazon, but little is known about the relationship between river colors and the incidence of the disease. In this sense, our results, by showing a significant association between the colors of the rivers and the incidence of malaria over time, seem to expand the understanding between physical-chemical characteristics of the rivers and the occurrence of malaria. ### Competing Interest Statement The authors have declared no competing interest.