COS 225-3 - Deforestation changes the effectiveness of bed nets for malaria control

Background/Question/Methods

Land use change, such as deforestation and degradation of tropical forests, is a key driver of infectious disease as it affects ecosystem dynamics and can increase transmission pathways. Studies have shown clear linkages between land use change and malaria, including the ecological mechanisms governing the disease transmission. Concurrently, programs that evaluate the effectiveness of malaria control strategies have highlighted the pathways how landscape changes can affect malaria control and eradication efforts. However, the evidence on the influence of deforestation on the effectiveness of malaria interventions is poorly understood. This study investigates how deforestation rates moderate the effectiveness of bed net use on malaria prevalence among children under five. We used multilevel hierarchical techniques to model a georeferenced dataset of demographic and health surveys linked with remote sensing ecological and climate data for 33817 children living in ten malaria-endemic sub-Saharan African countries.

Results/Conclusions

Our models support existing evidence that deforestation is associated with increased malaria prevalence and that bed net use is related to reduced malaria prevalence. We also found that the effectiveness of bed net use on malaria prevalence varies by deforestation levels. Bed net use is associated with reduced malaria prevalence in cluster areas with lower (5-20%) and intermediate (20-49%) levels of deforestation rates. At these levels of deforestation, the effect of bed net use reduces the odds of malaria by 23.4%-30%. In contrast, there was no evidence of an association between bed net use and malaria prevalence at the lowest (below 5%) and highest ( >=50%) deforestation rates. Our results suggest that spatial patterns of tropical forest loss, a key driver of malaria transmission, can affect the efficacy of malaria control interventions, and the two need to be considered together while designing environmental conservation and public health policy.