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"The earth is responding to escalating carbon dioxide levels with rising seas, flooding, droughts, forest fires, and a corresponding surge in infectious disease- some all too familiar; others new," says Timothy Ford from the University of New England in Biddeford, Maine.
"If properly done, predictive modeling will give us enough time to contain and possibly even prevent potential epidemic and pandemic diseases."
"Even though satellite measurements and other remote sensing techniques can't identify disease-causing pathogens and vectors directly, they can characterize the environments in which they thrive," says Peter Gilruth, who directs the Division of Early Warning and Assessment at the United Nations Environment Programme. "Environmental variables, including land and sea surface temperatures as well as the amount, type, and health of vegetation, can be accurately identified with remote sensing techniques. Sensors are being used to collect information from space, while powerful algorithms and image-processing software on desktop computers make it feasible for biologists and epidemiologist to experiment with spatial analysis technology."
 In the United States, the National Aeronautics and Space Administration oversees much of the remotesensing activities, while the National Oceanic and Atmospheric Administration operates valuable weather satellites. In addition, Canada, several European Union countries, Japan, and India have remote sensing satellites. While it would appear that the planet is being well watched, Ford decries "the crisis in U.S. funding that not only affects basic and applied research in this field but also undermines our ability to deploy sensing technologies that provide the most promising means of monitoring our environment.
"This is distressing because nothing is larger in scale, has more potential to cause long-term effects-and is more uncertain- than climate change when it comes to infectious disease outbreaks, epidemics, and pandemics," Ford continues. He cites environmentally driven zoonotic and vector-borne infectious diseases as examples and adds "insect or rodent vectors make it virtually inevitable that pathogens will be globally transported by plane or boat." More of Ford and colleagues' views on this subject can be found in the September issue of Emerging Infectious Diseases (DOI: 10.3201/eid1509.081334).
When climate change and increasing populations triggered reemergence of Rift Valley fever (RVF) in Senegal, Africa, the French National Space Agency (CNES) used its geographical information system (GIS) and remote sensing (RS) imaging technology to detect potential breeding ponds for Culex poicilipes, an important vector mosquito, according to Antonio Gu¨ ell at CNES. That information, combined with entomological data about the flying ranges and spatial distributions of mosquitoes, enabled the team to map high-risk RVF zones. Remote sensing data have similar applications in North America. For example, assessing high-risk areas where insect vector-borne diseases such as Lyme disease, the West Nile virus, and dengue fever are likely to show up next. Notably, the mosquito Aedes albopictus, a native of Asia that serves as a vector for both the West Nile and dengue viruses, recently established itself in North America.
"Yet, application of remote-sensing techniques to map areas at risk for dengue fever within this country has yet to be done," Gilruth says. "It should be emphasized that resource allocation for novel monitoring techniques should not come at the cost of basic disease prevention and management at the community level," Gilruth continues. Nor should ground-based data collection and transmission networks be ignored (Microbe, March 2009, p. 108). These systems supported by satellite imagery are vital for the control of environmentally dependent diseases, Güell adds.
Marcia Stone
Marcia Stone is a science writer based in New York City. More of her work can be seen at http://www.mstoneworks.net.
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