jacksonville, fl 9 – 12th february 2004 triennial gis symposium mapping of potential habitats for...
Post on 20-Dec-2015
212 Views
Preview:
TRANSCRIPT
9 – 12th February 2004 Triennial GIS Symposium Jacksonville, FL
Mapping of potential habitats for vectors of African Tick Bite Fever (ATBF) in the
Maasai Mara region of Kenya1C. Tungwony, 2M. Sardelis, 1S. Kasili, 1V. Sherwood, 1J Indiazi,
1S. Kelempu, 3A. Anyamba, 4A. Azad, 4K. Macaluso1 U.S. Army Medical Research Unit – Kenya 2 Uniformed Services University of Health Sciences 3 NASA 4University of Maryland
9 – 12th February 2004 Triennial GIS Symposium Jacksonville, FL
African Tick Bite Fever (ATBF) is a spotted fever caused by Rickettsiae africae and vectored by ticks
Rickettsiae africae was first reported in ticks in Maasai Mara, in 2003, following fatal tourist case
Maasai Mara is a national game reserve and popular tourist destination
Maasai Mara is characterized by diverse vegetation
GIS employed to help identify prevalent tick habitat
Introduction
9 – 12th February 2004 Triennial GIS Symposium Jacksonville, FL
The Maasai Mara Game Reserve and adjacent Conservation area totals 750 square miles
It is 2000m (5,200 ft) above the sea level
Inhabited by the Maasai community (livestock keepers)
It is characterized by shrubby grassland and riverine forest
Study Area: People and Vegetation
Maasai Mara National Game Reserve
9 – 12th February 2004 Triennial GIS Symposium Jacksonville, FL
Study Area: Rainfall and Temperature
Average Monthly Temperature
0
5
10
15
20
25
30
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
Month
Tem
per
atu
res
(o
C)
Maximiun Minimum
Average Monthly Rainfall
0
20
40
60
80
100
120
140
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
Month
Ra
infa
ll (
mm
)
9 – 12th February 2004 Triennial GIS Symposium Jacksonville, FL
Six Different vegetation types selected for tick collection
50 collection sites
GPS recorded locations of each collection site
Three collections: April, September, December (2002)
Collection methods: drags and picking off animals
Tick Collection
9 – 12th February 2004 Triennial GIS Symposium Jacksonville, FL
Sept 2002Apr 2002
1. LANDSAT images (Enhanced Thematic Mapper, Satellite 7) from USGS
Vegetation Classification – 3 Steps
9 – 12th February 2004 Triennial GIS Symposium Jacksonville, FL
2. Image processing
- Export to Idrisi 32
- Georeference
- Subset
- Natural Color composite
- Overlay GPS points
April
Vegetation Classification – 3 Steps
9 – 12th February 2004 Triennial GIS Symposium Jacksonville, FL
3. Supervised Classification (Maximum Likelihood) used to identify land cover types
September
Vegetation Classification – 3 Steps
April
9 – 12th February 2004 Triennial GIS Symposium Jacksonville, FL
3. Supervised Classification (Maximum Likelihood) used to identify land cover types
September
Vegetation Classification – 3 Steps
April
9 – 12th February 2004 Triennial GIS Symposium Jacksonville, FL
Results: April
KeyApril Collection
Village-density
1 - 10
11 - 20
21 - 40
40 - 60
60 - 100
1
2
3
4
9 – 12th February 2004 Triennial GIS Symposium Jacksonville, FL
Any stage
0
20
40
60
80
100
FOR GA GG TG TG&B ALL
% o
f si
tes
po
siti
ve
Sep Dec Larvae
0
20
40
60
80
100
FOR GA GG TG TG&B ALL
% o
f si
tes
po
siti
ve
Sep Dec
Nymphs
0102030405060708090
100
FOR GA GG TG TG&B ALL
Habitat
% o
f si
tes
po
siti
ve
Sep Dec
Adults
0102030405060708090
100
FOR GA GG TG TG&B ALL
Habitat
% o
f site
s po
sitiv
e
Sep Dec
Adult ticks were only collected in December and were Observed at all other habitats.
Summary of locations and life stages.
Ticks collected in all habitat types except Grazed grass
For habitats positive for ticks larvae was likely to be Encountered in other habitats.
Fewer Nymphs were collected compared to Larvae in all habitats
Summary
9 – 12th February 2004 Triennial GIS Symposium Jacksonville, FL
Density: Cattle, Goat and Sheep
KeySheep & Goat
0 - 41
42 - 137
138 - 258
259 - 500
501 - 1100
Cattle
0 - 26
27 - 83
84 - 180
181 - 350
351 - 600
9 – 12th February 2004 Triennial GIS Symposium Jacksonville, FL
Vegetation Index
• High index values characterizes dense vegetation
April
September
9 – 12th February 2004 Triennial GIS Symposium Jacksonville, FL
Conclusion
GIS can help visualize risk areas and, with identification of tick populations, map areas for control programs
Identify spatial and temporal relationships important in disease transmission
Model risk of contracting vector borne diseases
The study has indicated that this area is rich ground for further studies of ATBF
9 – 12th February 2004 Triennial GIS Symposium Jacksonville, FL
• Tanser, F.C; and Le Sueur, D. (2002) The application of geographical information systems to important public health problems in Africa. International journal of health geographics. Available from; http://www.ij-healthgeographics.com/content/1/1/4
• Lobitz, B. et al (1999) Climate and Infectious diseases: Use of remote sensing for detection of vibrio cholerae by indirect measurement. John Hopkins University
• Anno, S. et al (2000) Analysis of relationship between Anopheles subpictus larval densities and environmental parameters using remote sensing (RS), a global positioning system (GPS) and geographic information system (GIS). Kobe J. Med. Sci. 46, 231/243.
• Macaluso, K.R. et al (2003) Spotted Fever Group Rickettsiae in ticks from the Maasai Mara Region of Kenya. The society of Tropical Medicine and Hygiene. Am J. Trop. Med. Hyg., 68(5), 2003, PP. 551-553
• Rutherford, S.J. et al (2002) Spotted fever rickettsioses in Kenya (un published data)
References
9 – 12th February 2004 Triennial GIS Symposium Jacksonville, FL
Kenya Medical Research Institute
Mara Safari Club
Kenya Meteorological Department
International Livestock Research Institute
U.S. Geological Survey
Assaf Anyamba & Ed: GSFC - NASA
Acknowledgements
top related