19th Conference on IIPS


Use of Satellite Imagery for Epidemic Surveillance and Response

James M. Wilson V, Georgetown Univ. Hospital, Washington, DC

In late 1999, West Nile fever, which is caused by a mosquito-vectored virus, was identified in New York City during an epidemic involving 62 human cases and 7 fatalities. This was the first documentation of West Nile virus in the Western Hemisphere. It has been suggested the virus was transferred by accident via an infected human passenger arriving by airflight from the Middle East. The virus subsequently gained ecological establishment and now has been identified throughout the eastern United States, northward to Canada and as far south as Florida, with 50% of the continental U.S. effected within 18 months of initial introduction. The appearance of West Nile virus in a human community, like many insect-vectored pathogens, may be responsive to modulation by weather and climate variations (referred to as enviro-climatic modulation) and is deserving of closer examination. Serious concern remains that other insect-vectored exotic pathogens may also gain entry to the U.S by way of accidental or intentional importation. These pathogens may also be responsive to enviro-climatic modulation. Remotely sensed (RS) indices, such as NOAA's Normalized Difference Vegetation Index (NDVI), of proxy indicators and warnings of epidemic initiation and propagation represent an area of promise for the public health community due to implications for proactive versus reactive epidemic control measures. Increases in incidence for some infectious diseases have been attributed to modulation of endemic ecology via enviro-climatic coupling, and delineation of climatic patterns thought to influence the appearance of an infectious disease in a community can be directly applied to the development of an RS infectious disease surveillance system. Significant obstacles exist, however, regarding basic understanding of the mechanisms of epidemic triggering, propagation, and conclusion that hinder rapid development of RS disease forecasting systems. Idealization of remotely sensed disease surveillance system development includes a comprehensive understanding of the mechanisms involved in movement of the pathogen from its reservoir to humans and how it is maintained in the environment. Clear identification of how climate modulation effects this process is key. Ground verification of RS data through field meteorological studies is an additional requirement, which implies rapidly accessible, accurate, and reliable high resolution meteorological data. Disparities in temporal and spatial coverage exist for basic meteorologic variables such as precipitation, humidity, and temperature, and global accessibility of the data per WMO Resolution 40 is key for effective investigations of climate modulation of infectious disease incidence. With successful development of RS infectious disease surveillance systems, the need for access to real-time streaming meteorological data will become an increasingly important requirement for ground verification, as RS systems may be tested in an acute epidemic response scenario. This then becomes an urgent call for collaboration between the public health and meteorological communities in an era of concerns for importation of exotic pathogens and other infectious diseases.

extended abstract  Extended Abstract (84K)

Session 11, Satellite IIPS and Applications
Wednesday, 12 February 2003, 1:30 PM-5:30 PM

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