Race, immunity, and lifespan: Unraveling the effect of early-life exposure to malaria risk on lifespan.

We investigate a historical experience to measure the long-term effect of malaria on lifespan among infected survivors and identify a factor that mitigates malaria's effect. Using a sample of Union Army veterans born during the mid-19th century and their lifetime records, we show that exposure to high risk of malaria at birth or in early life substantially shortened their lifespan. The legacy of exposure to malaria is robust while controlling for lifetime socioeconomic and health conditions, fixed effects, and considering selection bias. Additionally, we include the US Colored Troops sample of black veterans to analyze racial differences in the effect of malaria exposure on lifespan. Exposure to malaria did not lead to a shorter lifespan among black veterans. Evidence suggests that genetic immunity to malaria in black veterans might contribute this heterogeneity.

Unintended health benefits of adopting preventive behaviors during a virus outbreak.

This study investigates whether changes in risk perception play a critical role in improving of preventive behaviors and health outcomes by examining the 2009 H1N1 influenza (or swine flu) pandemic in Korea. We employ a difference-in-differences estimation strategy by comparing the differential effects of the H1N1 outbreak on the confirmed cases of diseases which can be prevented by preventive behaviors (e.g., intestinal infections) and the cases of diseases which cannot (e.g., injuries). Using unique administrative data from South Korea's National Health Insurance Service (NHIS), we find that the exogenous increase in health risk reduced the incidence of intestinal infections compared to the injuries during the H1N1 influenza outbreak. The reduction was the most substantial among children under five years of age, with a 25.4% decline in cases of intestinal infections relative to injuries. Our findings are robust across various alternative specifications. We provide suggestive evidence that active adoption of preventive behaviors is one of the channels underlying the unexpected decrease in diarrhea cases. The effects, however, faded away shortly after the end of the pandemic and did not last in the long run.

Adapting to the Weather: Lessons from U.S. History.

An important unknown in understanding the impact of climate change is the scope of adaptation, which requires observations on historical time scales. We consider how weather across U.S. history (1860-2000) has affected various measures of productivity. Using cross-sectional and panel methods, we document significant responses of agricultural and individual productivity to weather. We find strong effects of hotter and wetter weather early in U.S. history, but these effects have been attenuated in recent decades. The results suggest that estimates from a given period may be of limited use in forecasting the longer-term impacts of climate change.

Malaria: an early indicator of later disease and work level.

This study investigates the effect of early-life exposure to malaria on disease and work level in old age over the past one and a half centuries. Using longitudinal lifetime records of Union Army veterans, I first estimate that exposure to a malarial environment in early life (c.1840) substantially increased the likelihood of having various chronic diseases and not working in old age (c.1900). Second, from data on US cohorts born between 1891 and 1960, I find that those exposed to a higher level of the anti-malaria campaign, which began in 1921, had lower levels of work disability in old age. Third, I seek the same implications for the modern period by linking WHO's country statistics on DALYs among older populations in 2004 to country-level malaria risk in pre-eradication era. In the paper, I discuss possible mechanisms and propose the significance of malaria eradication and early-life conditions from a long-term perspective.

MARRIAGE AND MEN'S WEALTH ACCUMULATION IN THE UNITED STATES, 1860-1870.

This paper explores how changes in marital status affected men's wealth accumulation in mid-nineteenth-century America, using a longitudinal sample of Union Army veterans linked to the 1860 and 1870 census manuscript schedules. Controlling for the endogeneity of wealth and marital selection, this paper provides strong evidence that marriage had positive effects on men's wealth accumulation, whereas ending a marriage had negative effects. The estimated wealth premium on married men is about 60 percent per marital year. This substantial wealth premium is closely related to wives' specializing in household production, and farmers and craftsmen economically benefited from the unpaid labor of their wives.

Survival in 19th Century Cities: The Larger the City, the Smaller Your Chances.

Using Union Army veterans' lifetime socioeconomic and health records, this essay finds a consistent and persistent hierarchy in survival rates and hazard ratios by urban size at and across three stages of life: birth, late adolescence, and death. This urban mortality penalty remains after controlling for variables associated with each individual veteran. The results of our geographical mobility analyses suggest that, with respect to these veterans, the search for an explanation should focus on late adolescence and adulthood as much as on early life. A complete explanation of the penalty requires a project of greater scope.

The Burden of Early Exposure to Malaria in the United States, 1850-1860: Malnutrition and Immune Disorders.

This article uses nineteenth-century evidence to calculate the impact of early exposure to malaria-ridden environments on nutritional status and the immune system in America. I estimate the risk of contracting malarial fevers in the 1850s by using correlations between malaria and environmental factors such as climate and geographical features. The study demonstrates that Union Army recruits who spent their early years in malaria-endemic counties were 1.1 inches shorter at enlistment due to malnutrition and were 13 percent more susceptible to infections during the U.S. Civil War as a result of immune disorders than were those from malaria-free regions.