Remotely sensed enviroclimatic patterns and ebola outbreaks linkages and early warning
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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. Outline. Ebola outbreaks: facts and hypotheses

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

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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


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)


  • Many Ebola outbreaks have occurred in African closed tropical forest

  • Some Ebola outbreaks have occurred in African gallery tropical forest within a savanna matrix


Outbreak Severity

385

210

79

47


Outbreak Locations


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


Possible Ebola Transmission(s)no usual suspects!

It is unknown where the virus dwells…


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


NOAA AVHRR 8-km NDVI Data Set

Radiation


VIS/NIR/SWIR Band Comparison

SPOT-VGT

SeaWiFS

AVHRR

MODIS


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

2003


Major Dataset Differences

Global NDVI anomalies


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


Hypothesis: very extreme change from rainy to dry season


1994 Ebola Outbreak Locations NDVI Time Series


Mean time series and anomalies


Spatial signatures and risk


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)


Trigger event summary


the hot zone


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