Evidence From 16 African Countries: Agriculture Is Linked To Malaria In Complex Ways

The African population is expected to triple by the year 2100. It means more food, water and agricultural commodities are needed. In meeting these needs, African governments and development agencies have set up large agricultural projects.

For example, the Alliance for African Rice Development, a policy framework, has set a target to double rice production from 28 million tons in 2018 to 56 million tons by 2030. Governments are also working to increase international trade in agricultural products.

Agricultural development involves the expansion of new farmland and intensive farming using irrigation or fertilizers to improve crop yields. Such development can improve household wealth, health care, education, and national GDP.

Sadly, when done the wrong way, it can also harm the environment. Agriculture can contribute to deforestation, carbon emissions, water and air pollution and biodiversity loss.

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In turn, these effects may harm human health. Certain infectious diseases – malaria, schistosomiasis and Buruli ulcer – have been linked to agriculture.

Agriculture and malaria have always been intertwined. The agricultural revolution made people live close to each other – near the water. But researchers have failed to fully understand, identify, or predict the links between agriculture and malaria.

To add to what is known about this, we examined whether childhood malaria in sub-Saharan Africa varies across types of agricultural landscape. We asked whether different forms of transplantation increase or decrease the risk of malaria in children. The land uses we considered were irrigated and rainfed croplands and systems that blend natural cover with crops.

We find patterns that indicate how farmland can be better managed to reduce health risk.This is important because the African continent still suffers from more than 90% of the world’s malaria deaths. The region’s progress toward malaria elimination has stalled in recent years.

We combined remotely sensed land cover and land use data with a geo-referenced malaria data set for 24,034 children in 12 countries. This malaria data covered the period from 2010 to 2015. Our analysis controlled for factors known to affect childhood malaria, such as the use of bed nets and insecticides. From our study,  the following agricultural landscapes increased the risk of childhood malaria across sub-Saharan Africa:

We also found that the presence of natural vegetation within agricultural land may reduce the incidence of malaria.

Agricultural expansion through rainfed or irrigated farmland appears to increase the risk of malaria in children in sub-Saharan Africa. While this is true for both rural or urban contexts, keeping some natural plants inside farmland can reduce the risks.

It is also known that keeping plants within agricultural land protects biodiversity and ecosystem functions and services. This makes farmland more sustainable in the long run.

Also in another study, we teamed up with AfricaRice and the International Institute of Tropical Agriculture to look at the link between rice and malaria in sub-Saharan Africa. Rice fields make wonderful breeding sites for mosquitoes, but it has often been emphasized that rice communities do not necessarily suffer from more malaria. He called this counterintuitive result the “paradox of fields”. But our study found that irrigated rice farming communities are exposed to more mosquitoes and also an increased risk of malaria. So the paradox is resolved. This can be explained by recent changes in Africa: more equitable distribution of malaria control interventions, which reduced the intensity of transmission overall.

competing priorities

Both studies confirm that agriculture is associated with increased malaria transmission in Africa.

This is concerning because three branches of development are currently trying to achieve their goals in isolation. African Ministries of Agriculture are planning agricultural expansion and intensification. Health ministries are planning to eradicate malaria. Environment ministries are trying to deal with the effects of deforestation, climate change and land use. Unfortunately, little has been done to reconcile these competing priorities. It is clear that more cross-sectoral collaboration is needed to achieve all of these goals.

Decision makers need more evidence about the causal relationship between agriculture and malaria. This would help them to choose between land use policy options in rural and urban systems. They will have a better understanding of how different measures, such as water availability, biodiversity loss, malaria elimination, carbon emissions, soil health and economic productivity, affect multiple aspects of sustainability.