Research Poster 36 x 48 - B

1
9. Geographic Information Systems and Geospatial
Analysis A 21st Century Tool for Epidemiology
and Public Health Management.
W. Vreeland ES473 Environmental Geology
DISCUSSION The Snow cholera map (Fig 1), is the
first and simplest example of GIS presented here.
It shows the spatial relationship between cholera
cases and led to the correct conclusion about the
source of the cholera outbreak. The dramatic
decrease in the cost of computing (Fig 2)
enables the study of more complex processes. The
correlation between the presence of malaria
vectors and land use (Fig 3) enables predictive
modeling of malaria risk based on geology, land
use, and seasonal factors such as rainfall and
river stage (Ageep). Public health authorities
can now target malaria vector eradication efforts
in the highest risk areas. This improves the cost
effectiveness of these efforts. This is very
important since malaria disproportionately
affects poorer developing nations. An exposure
intensity map of a presumed risk factor from the
Vinceti study of birth abnormalities around a
solid waste incinerator in Italy (Fig 4)
demonstrates how data from a limited number of
sample points can be extrapolated to infer risk
or exposure to environmental hazards. This study
found no correlation between exposure intensity
and birth abnormalities. Excluding exposure to a
toxin in the environment as a disease risk factor
is also an important result as demonstrated in
the final case study regarding the correlation
between consumption of well water and Parkinsons
disease in rural California. This study did find
a correlation between the risk factor (consuming
well water) and the disease. The presumed agents
in this study were agricultural chemicals in the
well water. Rather than test specifically for the
presence of the chemicals, this study used
detailed public records of pesticide applications
to create a model of exposure intensity. The
researchers could not rule out other exposure
routes in this study nor could they rule out that
exposure to other classes of chemicals such as
industrial waste and toxic metals may have also
played an important role in the observed increase
in disease. Calculating risk based on exposure is
extremely difficult. Not only are there thousands
of chemicals in the environment, the levels of
which are constantly changing over time, but,
people do not normally remain stationary for very
long. They therefore have a constantly changing
exposure profile. This study provided no graphs
or maps.
ABSTRACT Epidemiological studies involve
analyzing public health factors in the context of
time and space, with the goal of mitigating
disease outbreaks. Emerging advances in
computer processing power and cost are
facilitating research into linkages between
geospatially-distributed risk factors for illness
and disease. Geographic Information Systems (GIS)
provide a software technology that allows
scientists to easily link public health databases
to geospatial information and forms the
cornerstone of epidemiology in the 21st
century. Improved resolution of datasets allows
visual representation of complex, multilayered,
logical, numerical, and statistical relationships
between populations, risk factors, and known
or hypothesized causal factors. Geospatial
relationships combined with raw and processed
data enable researchers to identify, mitigate, or
prevent both epidemic and endemic disease
fostered by vectors that have a geographic
component. This developing technology comes with
the cost of upgrading computer workstations and
network bandwidth to accommodate the
geometrically increasing size of the datasets,
however the potential benefits to public health
management are significant. This paper provides
an overview of GIS applications in the public
health sector, and presents case studies
demonstrating the efficacy of the technology.
Figure 1 Dr. John Snow cholera map, 1854.
INTRODUCTION A geographic Information System
(GIS) can be as simple as points plotted on a
paper map with some attribute attached to the
points. One classic example of this is the map of
cholera cases prepared by Dr. John Snow during
the London epidemic of 1854. This map enabled
authorities to close the well at the center of
the cholera cluster and abate the epidemic. GIS
today involves sophisticated software and can be
integrated with Remote Sensing (RS) and Global
Positioning Systems (GPS) technologies to provide
real time monitoring of geological processes and
epidemiological vectors. The key element of GIS
is that attributes are related spatial and some
system is utilized to process and analyze these
relationships. The exponential decay in the cost
of computer resources is now enabling cost
effective studies at spatial resolutions that
could only be dreamed of a few decades ago. Using
the cost of computer hard drives as a proxy for
the overall cost of computing resources puts this
in perspective. A two terabyte hard drive can be
purchased today for as little as 149. The same
amount of disk storage would have cost about 2
billion in 1980. This poster examines three case
studies that rely on these technologies. These
studies examine the spatial and temporal
distribution of the Malaria mosquito, well water
consumption and Parkinson's disease in rural
California, and the risk of congenital anomalies
around a municipal solid waste incinerator in
Italy.
Figure 2 Graph depicting exponential decline in
computer hard drive storage as proxy for cost of
computing.
REFERENCES Ageep et al, 2009, Spatial and
temporal distribution of the malaria mosquito
Anopheles arabiensis in northern Sudan influence
of environmental factors and implications for
vector control Malaria Journal 8123
doi10.1186/1475-2875-8-123 Beale et al, 2008,
Methodologic Issues and Approaches to Spatial
Epidemiology Environ Health Perspect
11611051110 doi10.1289/ehp.10816 Bunnell et
al., 2005, GIS in Human Health Studies, in
Selinus, 2005 doi unavailable Gatto et al,
2009, Well-Water Consumption and Parkinsons
Disease in Rural California Environ Health
Perspect 11719121918 doi10.1289/ehp.0900852 Vi
nceti et al, 2009, Risk of congenital anomalies
around a municipal solid waste incinerator a
GIS-based case-control study International
Journal of Health Geographics 88
doi10.1186/1476-072X-8-8 Nielsen and Jensen,
2005, Environmental Epidemiology, in Selinus,
2005 doi unavailable Saxena et al,
2009,Application of spatial technology in malaria
research control some new insights Indian J
Med Res 130, August 2009, pp 125-132 doi
unavailable Weinstein and Cook, 2007,
Epidemiological Transitions and the Changing Face
of Medical Geology, Ambio, v. 36, no. 1 doi
unavailable
CONCLUSION GIS, RS, and GPS are now being
combined to provide a synergistic force
multiplier for efforts to monitor and improve
human health. The world is a very complicated
place. The human body is also very complicated.
Individual response to risk factors varies
greatly. GIS technology is now robust enough to
begin sifting through myriad temporal and spatial
relationships and categorize and quantify risk
factors that were not obvious just a few decades
ago. As the technology continues to evolve we can
expect that the cost of protecting human health
from geologic or spatially related risk factors
will diminish.
Figure 4 Exposure intensity map near a solid
waste incinerator, Italy
Figure 3 Map of mosquito larvae and water sources
along Nile River.