Background
Malaria and urbanization
Malaria and remote sensing
Malaria in Dakar
Objectives
Methods
Study site
Entomological data from the literature
Field entomological data collection
Geolocation of study sites
Satellite images and aerial photographs
Pre-processing of SPOT images
NDVI and distance to vegetation
Land use and land cover classification
Geographic information system (GIS)
Statistical analysis
Risk maps
Results
Image processing
GIS and statistical analysis
Catching point | N° of catching point | District | Geographic coordinates (Decimal degrees) |
An.
arabiensis
aggressiveness (number of bites /person/night,, averaged for 12 months) | Year* | Built-up area in 300-m radius buffer (Ha)** | Distance to vegetation (NDVI > 0.1) (m) | Risk map class from the final model |
---|---|---|---|---|---|---|---|---|
Usine Niari Talli | 1 | Centre | 14.7105; -17.4519 | 0 | ||||
1996 | 28.1 | 447 | Low | |||||
2007 | 28.2 | 449 | Low | |||||
Point E (Zone B) | 2 | Centre | 14.6976; -17.4558 | 0 | ||||
1996 | 26.0 | 149 | Medium | |||||
2007 | 26.8 | 189 | Low | |||||
SICAP Liberte I | 3 | Centre | 14.7083; -17.4605 | 0 | ||||
1996 | 25.3 | 286 | Medium | |||||
2007 | 28.0 | 409 | Low | |||||
HLM III | 4 | Centre | 14.7107; -17.4447 | 0 | ||||
1996 | 26.4 | 404 | Low | |||||
2007 | 27.5 | 449 | Low | |||||
Derklé- Castor | 5 | Centre | 14.7238; -17.4497 | 0 | ||||
1996 | 24.3 | 351 | Medium | |||||
2007 | 26.5 | 438 | Low | |||||
SICAP Liberte VI | 6 | Centre | 14.7244; -17.4630 | 0 | ||||
1996 | 16.2 | 55 | High | |||||
2007 | 26.0 | 181 | Low | |||||
Hann Village | 7 | Centre | 14.7177; -17.4365 | 0.15 | ||||
1996 | 21.0 | 167 | Medium | |||||
2007 | 21.5 | 162 | Medium | |||||
Cite des eaux | 8 | Centre | 14.7246; -17.4431 | 0.19 | ||||
1996 | 20.3 | 0 | Medium | |||||
2007 | 22.0 | 98 | Medium | |||||
Bop - Cerf Volant | 9 | Centre | 14.6992; -17.4498 | 0.38 | ||||
1996 | 18.0 | 117 | High | |||||
2007 | 18.5 | 25 | High | |||||
Hann - Pêcheurs B | 10 | Centre | 14.7286; -17.4234 | 0.46 | ||||
1996 | 14.5 | 343 | Low | |||||
2007 | 14.7 | 316 | Low | |||||
Hann - Pêcheurs A | 11 | Centre | 14.7192; -17.4320 | 0.85 | ||||
1996 | 19.1 | 55 | Medium | |||||
2007 | 21.0 | 65 | Medium | |||||
Zone des hydrocarbures | 12 | Centre | 14.7144; -17.4385 | 1.5 | ||||
1996 | 15.4 | 0 | High | |||||
2007 | 18.8 | 50 | High | |||||
Mboth (Plateau) | 13 | South | 14.6701; -17.4357 | 0 | ||||
1996 | 28.3 | 338 | Low | |||||
2007 | 28.0 | 317 | Low | |||||
Gueule - Tapée | 14 | South | 14.6802; -17.4572 | 0 | ||||
1996 | 28.2 | 487 | Low | |||||
2007 | 27.6 | 398 | Low | |||||
Diecko Nord (Médina) | 15 | South | 14.6752; 17,43237 | 0 | ||||
1996 | 28.3 | 424 | Low | |||||
2007 | 28.2 | 392 | Low | |||||
Niayes Thioker | 16 | South | 14.6716; -17.4413 | 0.04 | ||||
1996 | 28.2 | 351 | Low | |||||
2007 | 27.6 | 251 | Low | |||||
Fann - Hock | 17 | South | 14.6817; -17.4614 | 0.04 | ||||
1996 | 21.0 | 135 | Medium | |||||
2007 | 21.2 | 125 | Medium | |||||
Cite du port autonome (Plateau) | 18 | South | 14.6752; -17.4323 | 0.04 | ||||
1996 | 23.4 | 151 | Low | |||||
2007 | 24.1 | 295 | Low | |||||
Camp Dial Diop | 19 | South | 14.6587; -17.4371 | 0.18 | ||||
1996 | 13.2 | 28 | High | |||||
2007 | 18.5 | 90 | High | |||||
Caserne des sapeurs pompiers (av Malick Sy) | 20 | South | 14.6816; -17.4381 | 0.21 | ||||
1996 | 27.6 | 476 | Low | |||||
2007 | 27.1 | 343 | Low | |||||
HLM Fass | 21 | South | 14.6952; -17.4507 | 0.21 | ||||
1996 | 23.4 | 143 | Medium | |||||
2007 | 19.0 | 147 | High | |||||
Caserne gendarmerie de Potou | 22 | South | 14.6947; -17.4346 | 0.25 | ||||
1996 | 26.8 | 120 | Low | |||||
2007 | 26.8 | 491 | Low | |||||
Fann hôpital | 23 | South | 14.6900; -17.4663 | 0.79 | ||||
1996 | 7.2 | 7 | High | |||||
2007 | 12.3 | 0 | High |
Study area | N° of catching point | Geographic coordinates (Decimal degrees) | Total number of An. arabiensis (12 person/nights of capture in each study area) | An. arabiensis aggressiveness (number of bites/person/night, averaged for 12 months) | Built-up area in 300-m radius buffer (Ha)* | Risk map class from the final model |
---|---|---|---|---|---|---|
Pikine | 1 | -17.4634; 14.6892 | 180 | 2.50 | 15.2 | High |
Universite | 2 | -17.4322; 14.7321 | 138 | 1.92 | 10.6 | High |
Hann Maristes | 3 | -17.4711; 14.7453 | 60 | 0.84 | 15.0 | High |
Ouest Foire | 4 | -17.4443; 14.6849 | 49 | 0.68 | 18.2 | High |
Gibraltar | 5 | -17.4353; 14.7159 | 43 | 0.60 | 27.4 | Low |
Yarakh | 6 | -17.4600; 14.7238 | 42 | 0.58 | 21.9 | Medium |
Liberte 5 | 7 | -17.4448; 14.7496 | 8 | 0.11 | 27.8 | Low |
Grand Medine | 8 | -17.4803; 14.7609 | 3 | 0.04 | 26.4 | Low |
Yoff | 9 | -17.3987; 14.7584 | 1 | 0.01 | 27.1 | Low |
1996 SPOT-4 image (20 m) (Step 1) | 2007 SPOT-5 image (2.5 m degraded to 20 m) (Step 2) | |||||||
---|---|---|---|---|---|---|---|---|
Coefficient | 95% IC | p-value | Adjusted R2 | Coefficient | 95% IC | p-value | Adjusted R2 | |
Distance to vegetation (per 100 m and square root transformed) | -0.33 | -0.51; -0.15 | 0.0010 | 0.38 | -0.41 | -0.60; -0.21 | 0.0003 | 0.45 |
Built-up area in 300-m radius buffer (per Ha) | -0.04 | -0.06; -0.02 | 0.0005 | 0.42 | -0.06 | -0.07; -0.04 | < 0.0001 | 0.57 |
2007 SPOT-5 image (2.5 m degraded to 20 m) | ||||
---|---|---|---|---|
Coefficient | 95% IC | p-value | Adjusted R2 | |
Built-up area in 100-m radius buffer (per Ha) | -0.51 | -0.73; -0.29 | 0.0001 | 0.49 |
Built-up area in 200-m radius buffer (per Ha) | -0.13 | -0.18; -0.07 | 0.0001 | 0.51 |
Built-up area in 300-m radius buffer (per Ha) | -0.06 | -0.07; -0.04 | < 0.0001 | 0.57 |
Built-up area in 400-m radius buffer (per Ha) | -0.03 | -0.04; -0.02 | 0.0001 | 0.53 |
Built-up area in 500-m radius buffer (per Ha) | -0.02 | -0.02; -0.01 | 0.0004 | 0.44 |
2007 SPOT-5 image (2.5 m degraded to 20 m) (Step 3) | ||||
---|---|---|---|---|
Coefficient | 95% IC | p-value | Adjusted R2 | |
Built-up area in 300-m radius buffer (per Ha) | -0.07 | -0.10; 0.03 | 0.0037 | 0.68 |
Risk maps
Class | Risk | Built-up area in 300-m radius buffer | An. arabiensis aggressiveness evaluated from the model (number of bites/person/night) | Area of the risk class in 1996 (Ha) | Area of the risk class in 2007 (Ha) | Difference in risk class areas between 1996 and 2007 | % difference in risk class areas between 1996 and 2007 | % of the risk class area in 1996 | % of the risk class area in 2007 |
---|---|---|---|---|---|---|---|---|---|
1 | High | < 20 ha | [2.82 - 0.28[ | 1457 | 1195 | -262 | -18% | 32% | 20% |
2 | Medium | [20-26[ ha | [0.28 - 0.03[ | 1735 | 2267 | +532 | +31% | 39% | 39% |
3 | Low | > = 26 ha | < = 0.03 | 1319 | 2385 | +1066 | +81% | 29% | 41% |
Total | 4511 | 5847 | +1336 | +30% | 100% | 100% |