Do it well or not at all? Malaria control and child development in Zambia

We assess the impact of recent large-scale anti-malaria efforts on child development in Zambia. Unlike the interventions examined in prior work on the human capital effects of malaria, the Zambian efforts led only to temporary reduction in exposure to the disease: in the most highly affected areas, parasite prevalence declined markedly in the two years after the beginning of the program scale-up, but resurged soon thereafter in highly endemic areas. Comparing cohorts born before and after the campaign launch, we find that children with initially low but resurgent malaria exposure perform more poorly on cognitive tests, and no better on anthropometric and executive functioning, than children from the same areas with high exposure in the first two years, and varying exposure after age 2. These findings are not explained by mortality or fertility selection, changes in parental investment, or crowd-out of other health services and behaviors. Instead, we hypothesize (and provide suggestive evidence) that the adverse results flow from the children’s failure to form partial immunity to the disease in the first two years of life, making them more vulnerable to more severe illness when faced with resurgent disease. Our results suggest important tradeoffs between environment-driven early life developmental improvements and early life immunity development in models of human capital formation. They also suggest that sustained programmatic investment throughout childhood is critical to avoid potentially large adverse consequences of exposing non-immune populations to resurgent infectious diseases.