Popular

December 9, 2011

Nighttime Images Help Track Disease From The Sky

by editor

Normally used to spot where people live, satellite images of nighttime lights can help keep tabs on the diseases festering among them, too, according to new research.

Princeton University-led researchers report in the journal Science Dec. 9 that nighttime-lights imagery presents a new tool for pinpointing disease hotspots in developing nations by revealing the population boom that typically coincides with seasonal epidemics. In urban areas with migratory populations, the images can indicate where people are clustering by capturing the expansion and increasing brightness of lighted areas. The researchers found the technique accurately indicates fluctuations in population density – and thus the risk of epidemic – that can elude current methods of monitoring outbreaks.

The team used nighttime images of thethree largest cities in the West African nation of Niger to correlate seasonal population growth with the onset of measles epidemics during the country's dry season, roughly from September to May. The images, taken between 2000 and 2004 by a U.S. Department of Defense satellite used to obtain night-light data, were compared to records from Niger's Ministry of Health of measles cases from the same years. The team found that measles cases were most prevalent when a city's lighted area was largest and brightest.

Lead author Nita Bharti, a Princeton postdoctoral researcher in the Department of Ecology and Evolutionary Biology and the Woodrow Wilson School of Public and International Affairs, explained that people in nations such as Niger commonly migrate from rural to urban areas after the growing season.