The rise and fall of malaria under land use change
The ecology and evolution of Plasmodium parasites have been intimately connected to changes in land use since the dawn of agriculture. Today land transformation for human activities is one of the major forces driving ecological and socio-economic change around the world. Understanding how these changes would influence the emergence, maintenance, and elimination of malaria under different socio-ecological settings is therefore critical for developing successful control and mitigation efforts. In this talk we present the preliminary results of a mathematical model that combines land transformation, economic change, and malaria population dynamics in a unified analytical framework. By numerical simulation of the model under different ecological and socio-economic scenarios, we examine the dynamic consequences and patterns that emerge in both malaria and the economy over time.
Significant similarities in these patterns emerge despite model formulation differences in the ecology of the vector and the parasite as well as in socio-economic conditions. Specifically, we observe that in the early stages of land transformation malaria risk usually increases at a faster rate than the economic benefits of transforming the land. This pattern is then followed by a sharp decline in malaria burden as socio-economic conditions improve. Moreover, we show that under conditions of low socio-economic improvement and high environmental risk, the system can exhibit a regime of high levels in both malaria burden and poverty that can be long lasting and possibly stable. These patterns are consistent with observations from previous studies in two regions of the world under different drivers of land-use change: deforestation in the Amazon and irrigation development in semi-deserts of India. We discuss the implications of these results for malaria today in these two dissimilar areas of the world under global climate change.