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Remotely-sensed Enviroclimatic patterns and Ebola outbreaks: linkages and early warning

Explore the correlation between environmental factors and Ebola outbreaks in African forests. Utilizing remotely-sensed data, the study examines spatial and temporal specifics of trigger events for early warning. By analyzing environmental links, potential transmission scenarios among different hosts are investigated. The study uses datasets from 1980-2010, including moderate-resolution environmental satellites, to identify unique characteristics at outbreak sites. Techniques such as Canonical Correlation Analysis are applied to detect enviroclimatic signals typical of known outbreak locations and dates.

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Remotely-sensed Enviroclimatic patterns and Ebola outbreaks: linkages and early warning

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  1. Remotely-sensed Enviroclimatic patterns and Ebola outbreaks:linkages and early warning Dan Slayback Jorge Pinzon Compton Tucker 8 September 2004 Biospheric Science Branch, Code 923 NASA Goddard Space Flight Center Greenbelt MD 20771 USA

  2. Outline • Ebola outbreaks: facts and hypotheses • Environmental links to remotely sensed data • Spatial & temporal specificity of environmental trigger events • Conclusions From: Trigger events: enviroclimatic coupling of Ebola hemorrhagic fever outbreaks. 2004. JE Pinzon, JM Wilson, CJ Tucker, R Arthur, PB Jahrling, and P Formenty, American Journal of Tropical Medicine and Hygiene. (in press)

  3. Many Ebola outbreaks have occurred in African closed tropical forest • Some Ebola outbreaks have occurred in African gallery tropical forest within a savanna matrix

  4. Outbreak Severity 385 210 79 47

  5. Outbreak Locations

  6. Transmission Scenarios Community Epidemic Scenario • Secondary transmission within species. • Reciprocal transmission between species. APES/HUMANS INTERMEDIATE HOST RESERVOIR Peter Walsh et al. Nature (2003) Just because a species tests positive for virus or antibodies does not mean that it is a link in the chain of transmission to apes. “Cul de Sac” Hosts Cul de Sac HOST--HUMANS? APES RESERVOIR

  7. Possible Ebola Transmission(s)no usual suspects! It is unknown where the virus dwells…

  8. Environmental Links withRemotely Sensed Data:available datasets 1980 1985 1990 1995 2000 2005 2010 Moderate-resolution (1-10’s kms) environmental satellites MODISes NOAA-16 AVHRR NPOESS NOAA 14 AVHRR NOAA 11 AVHRR NOAA 9 AVHRR SPOT NOAA 7 AVHRR SeaWiFS NOAA9

  9. NOAA AVHRR 8-km NDVI Data Set Radiation

  10. VIS/NIR/SWIR Band Comparison SPOT-VGT SeaWiFS AVHRR MODIS

  11. New, improved 8-km AVHRR NDVI data set 1981-present 2003

  12. Major Dataset Differences Global NDVI anomalies

  13. Are there unique environmental characteristics at outbreak sites, during the outbreak year?

  14. Hypothesis: very extreme change from rainy to dry season

  15. 1994 Ebola Outbreak Locations NDVI Time Series

  16. Mean time series and anomalies

  17. Spatial signatures and risk

  18. Canonical Correlation Analysis (CCA) • CCA is a method that maximizes the variance between two datasets. Here, we use CCA to identify areas and times that exhibit enviroclimatic signals typical of those at known outbreak sites and dates. • CCA(A) = [U,S,V] • A: paired-mode correlation matrix between yearly NDVI signals and corresponding NDVI signals from the outbreak sites at outbreak years. • U: orthonormal vector of satellite NDVI signals • S: percentage of covariance explained by canonical factors • V: orthonormal vector of Ebola sites • The analysis conducted only over areas with high enviroclimatic correlation to previous outbreak sites (r2 > 0.95)

  19. Trigger event summary

  20. the hot zone

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