From Satellites to Sand Flies: Peering into Sudan from Space
By Alex Sweeney, Climate and Society ’13
In Eastern Sudan, where cracking soils and Acacia-Balanites woodlands dot the landscape, there roams a ferocious little female bug whose bite packs a serious punch. The female sand fly, of the genus Phlebotomus, has a terrifying and death delivering parasitic unicellular organism residing within it, Leishmania donovani, responsible for the disease, Visceral Leishmaniasis (VL), affecting people worldwide.
VL is responsible for 40,000 deaths, with 400,000 new cases emerging globally every year (Medecins Sans Frontieres, 2013). However, due to lack of reporting, these figures are expected to be much higher. In terms of vector borne diseases, most public health news and stories focus on Malaria, while VL glides effortlessly under the radar. Although VL occurs in 65 countries worldwide, five countries account for 90% of all cases (Desjeux,2004). Sudan is one of them.
On the eastern border of Sudan lies Gedaref state, a region where VL is endemic. And although it occurs naturally within this area, there have been severe epidemics in the recent past. Because of this, there has been a surge of interest to understand the ecological and environmental parameters surrounding the sand fly (insect vector) of VL. Understanding these boundaries can help formulate an Early Warning System that can help identify and forecast conditions that increase the likelihood of transmission. A similar system has already been developed for Malaria. This fusion of public health and environment was the focal point for my summer internship with NASA Develop. Using NASA Earth observations and remote sensing products, we can determine the favorable conditions for sand flies from thousands of miles away.
Only recently had I discovered how one could use satellites orbiting the Earth to benefit public health. During my spring semester at Columbia, I enrolled in a remote sensing class taught by my current supervisor, Dr. Pietro Ceccato, a researcher at the International Research Institute for Climate and Society (IRI) and Michael Bell, also from the IRI. Together they unraveled the complexities of satellite products and applied it to different facets of society. They taught us not only how to access the immense amount of remote sensing products available, but also how to navigate through the IRI Data Library. Through this medium we can isolate different periods and locations of data and perform statistical analyses in order to better understand the climate of particular regions. Without a doubt, the skills and knowledge I learned this past spring has been the largest asset to my internship.
As our climate begins to display different trends in response to higher atmospheric carbon dioxide levels, understanding vector borne diseases and how vectors will react to deviations from the typical climate that characterizes a region will be increasingly important for public health. Further, in a region such as Gedaref, where the practicality of on the ground instruments is poor, Earth observing satellites and their products (such as those created by NASA) enable scientists and decision makers to research a problem and collaborate on a solution.
Studying a fatal disease and trying to understand the characteristics that help it’s insect vector flourish, is a bit unsettling. Especially when you’re thousands of miles removed (on second thought – perhaps it’s better to be thousands of miles away). But learning how to reel in all of the useful information gathered by Earth orbiting satellites and connecting it to real world risks has been fascinating and necessitates hope. Hope in the vast potential to coalesce concrete science information with obtainable solutions that will alleviate hardships faced by people across the globe.
Desjeux, P. (2004). Leishmaniasis: current situation and new perspectives.Comparative
immunology, microbiology and infectious diseases, 27(5), 305-318.
Medecins Sans Frontieres (MSF). (2013). Kala Azar. Retrieved from http://www.doctorswithoutborders.org/news/issue.cfm?id=2394.