Malaria Population Dynamic and Climate Forcing Under Agricultural Development.

Abstract

Malaria and human prosperity had been intimately connected since the beginning of human civilization through agriculture, and today most of its burden is concentrated in poor and rural communities. While this connection has been recognized, the contribution of agricultural development on the distribution and abundance of malaria, and the influence of the feedback that can operate between the disease and the agrarian economy, remains poorly understood. The purpose of this dissertation is to examine the role of irrigation and agricultural development in determining the distribution, abundance, and dynamics of malaria populations and simultaneously the role of malaria on human behavior related to mosquito control policy and economic productivity. This dissertation examines the current malaria situation in the semi-desert and monsoon-driven region of Northwest India and, retrospectively, malaria elimination in Mississippi, United States.

This work shows that in highly irrigated areas malaria predictability based on rainfall is reduced due to intense vector control programs, most successfully implemented by authorities in more prosperous and irrigated places. I show that this vector control strategy generates a mechanistic feedback between the disease and the control itself, which decreases the effectiveness of the intervention and the likelihood of elimination. In addition, I provide evidence suggesting that this period of high risk and high control in irrigated settings is a transient period, lasting for more than a decade when poor areas with low irrigation development transition to becoming areas with sustainable low risk and better socioeconomic conditions. Finally, I provide evidence to suggest that income and other economic factors had a large influence in driving malaria interannual variability and its elimination in Mississippi. The influence of malaria on cotton production, which dominated the economy of the region at this time, was limited.

Together, the results from this dissertation provide insight to support the idea that including socioeconomic factors, while indirectly related to malaria transmission, with detailed ecological knowledge of the malaria system can provide valuable information to generate more sustainable and effective strategies to decrease malaria burden and eventually eradicate the disease.