Principle Investigators: Dr. Zeyan Liew, Assistant Professor, Environmental Health Sciences, Yale School of Public Health.

This project is the first study in the United States to examine the relationship between ambient temperature exposure and childhood epilepsy. Drawing on an established California statewide birth cohort of over 4 million children born between 2007 and 2015, the research investigates how exposure to high ambient temperatures — both during pregnancy and in early childhood — may relate to the risk of developing epilepsy and to the occurrence of epileptic seizures.

Using case-cohort and case-crossover study designs, the project pairs rigorous exposure and outcome assessment with careful statistical analysis. By establishing whether early-life heat exposure influences neurological outcomes, the study aims to generate preliminary evidence that can support a larger, externally funded investigation into the effects of a warming climate on children’s health.

Co-principal investigators: Tormod Rogne, MD, PhD, Assistant Professor (Chronic Disease Epidemiology), YSPH; Xiaomei Ma, PhD, Professor (Chronic Disease Epidemiology), YSPH; Nicole Deziel, PhD, Associate Professor (Environmental Health Sciences, YSPH)

Abstract: There is increasing awareness of how ambient temperatures during pregnancy affects the risk of adverse birth outcomes. However, very little is known about the longer-term consequences for the offspring due to prenatal exposure to extreme ambient temperatures. We aim to conduct the first study to evaluate the association between ambient temperature during pregnancy and risk of childhood acute lymphoblastic leukemia (ALL). We propose to conduct a nested case-control study of childhood ALL (age 0-14 years) within a birth cohort from California. By linking cancer diagnoses reported to the California Cancer Registry from 1988-2015 and statewide birth records from 1978-2015, we have established a large, population-based California Linkage Study of Early-Onset Cancers. With 6,340 primary cases of childhood ALL and 50 times as many controls (n = 317,000), this study population is the largest of its kind, and offers a unique opportunity to evaluate whether ambient temperature in pregnancy is associated with offspring risk of childhood ALL. The pilot funding will be used to estimate ambient temperature exposure of the study population during pregnancy, using geocoded maternal address at the time of the child’s birth. Different sensitive windows during pregnancy will be explored, in addition to one month pre-conception (assumed to have no direct effect on ALL other than through correlation with temperature in early pregnancy). It is key to understand what factors contribute to the likelihood of developing childhood ALL so that appropriate mitigation strategies may be put in place. Funding provided by the Yuet Mei Chin Innovation Fund for Junior Faculty.

Co-principal investigators: Dr. Michelle L. Bell, Mary E. Pinchot Professor of Environmental Health, School of Forestry and Environmental Studies; Dr. Joshua L. Warren, Associate Professor, School of Public Health, Biostatistics.

Abstract: The world is undergoing unprecedented urbanization with a growing fraction of the population living in cities, which contributes to an urban heat island effect. Simultaneously, climate change is increasing the overall temperature and temperature extremes (e.g., heat waves). Previous research indicates that greenspace improves health; however, little is known about the temporal trends in how greenspace affects health. Decisions made regarding urban greenspace in upcoming years will have impacts on health for many decades. To understand greenspace and health in a changing climate, scientific evidence is needed on how the health impacts of urban greenspace change over time within this complex system. We propose to: 1) estimate exposure to greenspace using satellite exposure at the ZIP-code level for 10 major United States (U.S.) cities, including how these exposures change over time; 2) develop a statistical model to estimate the temporal trend in the association between greenspace and risk of cardiovascular and respiratory hospital admissions for older persons in the U.S.; and 3) apply the exposure estimates from Aim 1 and modeling method in Aim 2 to estimate how the association between greenspace and hospital admissions changes over time. These findings will provide the preliminary data and methods to be used in an R01 to investigate the system of greenspace, temperature, climate change, and health, including temporal trends in health effects. Results from the pilot study and the larger project will inform city-level decision makers in developing the most effective climate change mitigation strategies.

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.

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.

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.