Sewage that overflows into urban creeks and streams during periods of heavy rain can promote the spread of West Nile virus, a study led by Emory University finds.
The analysis of six years of data showed that people living near creeks with sewage overflows in lower-income neighborhoods of Southeast Atlanta had a seven times higher risk for West Nile virus than the rest of the city.
"The infection rate for mosquitoes, birds and humans is strongly associated with their proximity to a creek impacted by sewage," says Gonzalo Vazquez-Prokopec, the Emory disease ecologist who led the study. "And if the creek is in a low-income neighborhood, we found that the entire cycle of infection is even higher."
More affluent residents are more likely to have air-conditioning and use insect repellant and other protective measures, the researchers theorized.
The study, published in the current issue of Environmental Health Perspectives, was a collaboration of Emory, the Centers for Disease Control and Prevention, the Georgia Division of Public Health, the Fulton County Department of Health and Wellness, the National Institutes of Health, the Fogarty International Center and the University of Georgia.
According to the Environmental Protection Agency, about 850 billion gallons per year of untreated mixed wastewater and storm water are discharged into U.S. urban waters, mainly through combined sewer overflow (CSO) systems that are used in more than 700 cities. Under normal conditions, CSO systems channel wastewater to a treatment plant before it is discharged into a waterway. During periods of heavy rain or snowmelt, however, the wastewater flows directly into natural waterways after only minimal chlorine treatment and sieving to remove large physical contaminants.
Most of the available data on the human health impacts of sewage-affected waterways focuses on the effects of exposures to bacteria, heavy metals, hormones and
|Contact: Beverly Clark|