The long-term effects of early life malaria exposure: Evidence from Taiwan's malaria eradication program in the 1950s

Malaria is one of the most important public diseases in human history, and still persists in some less developed areas even until today. The short-term effects of malaria exposure have been studied thoroughly, and previous studies on the long-term effects of malaria exposure mainly focus on education and economic outcomes. Our paper is the first to systematically examine the long-term health effects of malaria exposure, using unique and comprehensive national health insurance data (NHID) from Taiwan. In this paper, we utilize the variation of decreases in malaria prevalence generated by the World Health Organization’s malaria eradication program, to isolate the actual effects of early life malaria exposure on future outcomes. More specifically, we compare future outcomes of cohorts born before and after the eradication era in counties with different decreases in malaria prevalence. The basic idea is that counties with larger decreases in malaria prevalence should benefit more from the malaria eradication program.

Our paper has the following four key contributions. First of all, we use unique and comprehensive NHID from Taiwan, to systematically study the long-term health effects of early life malaria exposure. Taiwan’s NHID contain medical records of all Taiwan’s residences. This paper utilizes both the inpatient records and catastrophic illness records, to study the long-term effects of early life malaria exposure on future chronic diseases (heart disease, stroke, and hypertension) and catastrophic illnesses (such as malignant neoplasm, chronic renal failure, systemic autoimmune syndrome, and so on). Considering the potential gender difference, we carry out our analysis separately for males and females. Second, besides health outcomes, we derive the education and labor market outcomes from the Taiwan census data, which also contain the full sample of Taiwan’s residents. Third, we have a more precise measure of the decrease in malaria exposure. The Taiwan’s Health Statistics Yearbook contains information of malaria prevalence both before and after the initial of the malaria eradication program. Most previous studies only have pre-eradication malaria prevalence, and assume the malaria prevalence drops to zero after the malaria eradication program. Fourth, we have better defined birth cohorts. In this paper, we use only people in four continuous birth cohorts to identify the effects of malaria eradication, while previous studies have used much wider birth cohorts.

We have three important findings. First, the education outcomes of both genders have significantly improved due to the malaria eradication program. Second, we find that the job participation rate of females, but not of males, has significantly increased due to the malaria eradication program. Third, malaria eradication is associated with better future health outcomes of both women and men: the eradication program has lowered the 12-month prevalence of women’s ischemic heart disease, women’s ischemic stroke, and men’s hypertension. However, there is no any significant effect of malaria eradication on future catastrophic illnesses of both genders.