Environmental science strengthens our understanding of climate and infectious diseases

Heavy rainfall and flooding have long been known to increase the risk of waterborne infectious diseases by exposing people to contaminated floodwaters and overwhelming water and sanitation systems. In a study published in the latest edition of the American Journal of Epidemiology, researchers in EHS found that, without accurate measurement of climate variables like rainfall, we may substantially underestimate the impact of extreme weather on the global incidence of diarrheal diseases, which remain among the leading causes of child mortality.

“Pathogens spread by water can disperse and persist in the environment during heavy rainfall and floods, causing disease in locations and among people far from their original sources,” said Dr. Morgan Levy, a postdoctoral fellow and environmental scientist in EHS who led the study. “In our collaboration between earth scientists and epidemiologists, we found that the greater the distance between measurements of extreme rainfall and vulnerable populations, the more we underestimate the impact of extreme events on health,” says Levy.

Using simulation studies and an analysis of health and environmental data from research in northern coastal Ecuador, the study found that when rainfall is measured far from a vulnerable population, the estimated effect of extreme rainfall on diarrheal disease incidence is underestimated by as much as 45%.

“Our results demonstrate how important it is to accurately assess exposure to extreme weather events, particularly in developing countries where environmental information is limited, and where the frequency and intensity of extreme weather are expected to change with a changing climate,” Levy added.

As the global climate changes, populations are vulnerable to a range of new conditions—from more frequent heat waves to more intense hurricanes—that will impact health. “What Morgan’s research shows is that rigorous epidemiological research on the health effects of a changing climate will require deep collaboration with earth scientists,” said Professor Justin Remais, Head of Environmental Health Sciences at the Berkeley School of Public Health. “By committing to improved characterization of environmental processes, including rainfall and other variables, we stand the best chance of understanding and responding to the health effects of extreme climate, and can take the most appropriate actions to protect populations from these exposures.”

The research team included scientists from the University of Michigan, University of Colorado, Emory University and University of Nevada Reno.

The study was supported by grants from the National Institute of Allergy and Infectious Diseases, the National Science Foundation, and the National Institute of Health’s Fogarty International Center.

Links:

Prof. Justin Remais’ research group

Peer-reviewed manuscript