Pilot Project Awards


Title: Consequences of climate change for risk of enteric infections: investigating links
between hydrology and water-borne disease

Principle Investigators: Virginia Pitzer, PhD, Assistant Professor, Department of Epidemiology of Microbial Diseases, Yale School of Public Health; Daniel Weinberger, PhD, Assistant Professor, Department of Epidemiology of Microbial Diseases, Yale School of Public Health; William Boos, PhD, Associate Professor, Department of Geology and Geophysics, Yale University

To predict the impact of climate change on future infectious disease incidence, it is essential to
robustly quantify the climate-disease relationship. Appropriately attributing changes in disease
incidence to climate change often requires building a mechanistic understanding from relatively
short time-series of climatic variables and disease incidence—a process that relies on
harnessing spatial variation and/or biological knowledge. We will focus on quantifying
associations between water-borne enteric diseases and hydrologically-relevant climatic
variables. Using a meta-regression approach, we will reevaluate studies that have examined the
effect of climate on enteric diseases across a wide range of geographic locations. We will seek
to identify the sources of heterogeneity and relevant climatic variables that lead to more
consistent findings than have been previously reported. We will then focus on one particular
climate-disease system—precipitation and typhoid fever in Kathmandu, Nepal—and employ
both statistical and mathematical models to quantify the relationship between various
hydrological metrics, bacterial contamination of water supplies, and the incidence of typhoid
fever cases while controlling for epidemiological and immune-driven feedbacks over a 14-year
time period. These analyses will provide the foundation and methodological developments
necessary to inform future studies that link predictive models of enteric disease incidence to
climate change projections.


Title: “Effects of extreme climate events on environmental reservoirs and dispersion of

Principal Investigator: Dan Weinberger, PhD. Assistant Professor of Epidemiology, Yale School of Public Health

Legionella pneumophila is a poorly understood but increasingly common cause of community
acquired pneumonia in the US. The bacterium has been studied separately in the hydrological
and epidemiological sciences, but we propose a unique collaboration between these fields to
further our understanding of Legionella. More specifically, we will clarify the role of climate
change—particularly warming temperatures and high intensity storm events—on the spread of
Legionella and resulting clustering of non-outbreak “sporadic” disease. Expertise will come from
an interdisciplinary team of researchers from epidemiology and biostatistics at Yale School of
Public Health, biogeochemists at Yale School of Forestry, and public health practitioners from
the Connecticut Emerging Infections Program/Department of Public Health. Our study would
use a mix of quantitative analyses of existing public health data and testing of environmental
water and aerosol samples to evaluate hypotheses about the observed long-terms trends and
spatial variations in the incidence of legionellosis. Outcomes will include identification of drivers
for environmental Legionella “hot spots”, estimation of the time Legionella remains suspended in
water and aerosols after intense storm events, and elucidation of threshold climatic events that
significantly increase rates of disease. These data and models will then be used to generate
forecasts of legionellosis under different climate change scenarios. The proposed studies will
provide important information regarding the climatic drivers of an emerging infection of public
health significance.


Title: Ambient temperature and risk of ischemic stroke in the elderly

Principal Investigator: Judith Lichtman, PhD, MPH, FAHA, Associate Professor and Chair, Department of Chronic Disease Epidemiology, Yale School of Public Health

Stroke is a major public health problem in the United States, with an estimated 800,000 strokes each year and an estimated 7 million stroke survivors. It is the fifth leading cause of death and a leading cause of serious disability in adults. Because the population is aging, the number of adults at risk for stroke will increase over the coming decades. Climate change, including more frequent episodes of extreme heat and cold, may impact stroke incidence. Seasonal variation in stroke rates has previously been reported, but data from the United States are limited regarding the relationship between temperature and stroke. We propose a pilot study to assess the impact of meteorological exposures, including daily and weekly fluctuations in temperature as well as heat waves and cold spells, on 1-year stroke incidence among elderly Medicare fee-for-service beneficiaries across the country. The study will link Medicare inpatient hospital claims data and National Centers for Environmental Information temperature data to conduct both time-series and case-crossover analyses, with adjustment for air pollution. This project will be the largest study of ambient temperature on stroke events in the United States, and it will provide important preliminary data to demonstrate the utility of Medicare data for evaluating the role of ambient temperature on stroke events. We will use the results as a basis for an R01 application that will investigate changing patterns of ambient temperature over more than a decade on stroke events as well as assess the impact of a greater range of air pollutants.