a. townsend peterson, carmen martinez-campos, yoshinori nakazawa, enrique martinez-meyer
DESCRIPTION
Time-specific ecological niche modeling predicts spatial dynamics of vector insects and human dengue cases. A. Townsend Peterson, Carmen Martinez-Campos, Yoshinori Nakazawa, Enrique Martinez-Meyer. - PowerPoint PPT PresentationTRANSCRIPT
Time-specific ecological niche modeling predicts spatial
dynamics of vector insects and human dengue cases
A. Townsend Peterson, Carmen Martinez-Campos, Yoshinori Nakazawa, Enrique Martinez-Meyer
Peterson, A. T., C. Martínez-Campos, Y. Nakazawa, and E. Martínez-Meyer. 2005. Time-specific ecological niche modeling predicts spatial dynamics of vector insects and human dengue cases. Transactions of the Royal Society of Tropical Medicine and Hygiene 99:647-655.
Dengue
Is caused by a virus from the genus Flavovirus.
Transmitted by a mosquito (Aedes aegypti).
Tropical and subtropical regions of the world.
Create time specific ecological niche models that help us understand the spatial and temporal dynamics of the mosquitoes.
Predict future outbreaks.
Data
Point-occurrence of Aedes aegypti drawn from larval surveys (Laboratorio de Entomologia, InDRE)
Monthly samples from eastern and southern Mexico.
Data from April to December 1995.
Mosquitoes
InDRE: Instituto de Diagnostico y Referencia Epidemiologica.
Environmental data
Monthly maximum value composites of NDVI for 1995. From AVHRR.
Topographic variables from USGS Hydro-1k: DEM, slope, aspect and topographic index.
Methods
Absent1 - 49% of models50 - 79% of models80 - 100% of models All points all NDVI
Methods
Data2
Data1
Data4
Data3
Data5
Month2
Month1
Month4
Month3
Month5
MODIS NDVI
DATA
Model2
Model1
Model4
Model3
Model5
Include information about conditions from previous months:
NDVI(t) - NDVI(t-1)NDVI(t) - NDVI(t-2)
Time specific predictions
Time specific model
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
NDVI(t) Elevation NDVI(t-2) NDVI(t-1) Slope Topographic index
Aspect
Cor
rela
tion
coef
ficie
nt
Methods: Transmission cycle
Human case data drawn from cases tested by InDRE.
-Incubation in mosquito-Infection of human-Incubation in human-7 days for taking sera after onset of symptoms.
(Total: 18days)
Methods: Future
- Models for each month
- Models projected to all other months
- Average of models from two previous months (t-1 and t-2) projected to the current (t)
- June August- July August
- Overlay of occurrences (t)- August
- Evaluate predictions
Predict future distribution
Average models from previous months
Predict future distribution
Percent correctly predicted Statistical significance
Month (1995)Number of test
points Any>50% of models >80% of models Any >50% of models >80% of models
June 22 100.0 72.7 54.5 * * *
July 28 100.0 82.1 67.9 X * *
August 40 100.0 75.0 35.0 + * *
September 25 100.0 80.0 16.0 X *
October 19 94.7 78.9 21.1 X
November 25 100.0 76.0 52.0 X +
December 22 100.0 95.5 81.8 X + *
* Strong significance+ Marginally significantX Not significant
Predict future distribution
Predict future outbreaks
Conclusions
Time-specific models seem to perform better.
Recover the spatial and temporal dynamics of the disease through ENM.
Predict areas where an outbreak is more likely to occur.
-- Inclusion of human population data/variables.