Gainesville, US: Using satellite images to measure night-time light levels streaming from West African cities could prove to be an important new tool in fighting the spread of measles, according to a new study published in the December 9 issue of the journal Science.
Researchers claimed that the method could be used to control other diseases such as meningitis that spread quickly through dense populations. The research team, including a scientist from the University of Florida, analysed night-time satellite images of three cities in Niger taken between 2000 and 2004, and found that seasonal population surges correlated strongly with local measles epidemic outbreaks recorded for the same period. The epidemics kill thousands annually in West Africa, although the disease has been largely eradicated in the US through long-standing immunisation programmes.
The research showed that satellite images of city lights can reliably predict a likely outbreak by indicating where the highest concentrations of people are. In Niger, measles outbreaks occur when people crowd into the cities during the dry season each year to find work. Until now, there has been no way to assess how many people were moving into the cities and where the highest concentrations of people were.
“In the US, light levels would saturate satellite imagery to the point that it couldn’t tell us much about the details of population distribution within a city,” said study co-author Andrew Tatem, a UF assistant professor of geography who specializes in spatial data modelling and analysis. “But in Niger, when people gather in numbers and turn on electric lighting or light fires at night, you can see it from outer space.”
The researchers used data from the National Oceanic and Atmospheric Administration that is available to the public online.