Slide 1

Report
Mapping for Surveillance and
Outbreak Investigation
Mapping for Surveillance and
Outbreak Investigation
This issue of FOCUS was adapted from the following
online training on the NCCPHP Training Web Site
(http://nccphp.sph.unc.edu/training/):
Infectious disease surveillance and outbreak
investigation using GIS (2004)
Dionne Law, PhD, Spatial Epidemiology Research Associate
Department of Epidemiology, University of North Carolina at
Chapel Hill
Goals
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Describe ways maps can be used in field
epidemiology
Describe how geographic information systems
(GIS) can display and analyze spatial data
Provide examples of surveillance and
outbreak investigation activities that relied on
GIS
Describe the use of global positioning
systems (GPS) to increase GIS
capabilities
Mapping for Surveillance and
Outbreak Investigation
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Maps are commonly used in epidemiology to
present complicated information succinctly
and clearly
This issue discusses:
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How maps can be used in field epidemiology
Commonly used computer software programs that
can capture and analyze data and integrate them
into a spatial display
Maps
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Earliest documented
epidemiologic study
relied on mapping
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Dr. John Snow’s
investigation of cholera
outbreak, London, 1854
Used maps and statistical
data to trace source of
outbreak to public water
pump on Broad Street
Maps
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Most noted example of maps to convey
complicated statistical information
comes from outside public health (1)
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1869 map of French army’s march to and
retreat from Moscow
Displays multivariate data (army size,
direction, geographic location,
temperature, and time)
Maps
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Line widths show size of French army on advance
to Moscow (tan) and retreat (black)
Chart below lines plots temperature
Maps
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Map created during disease surveillance
and response activities around avian
influenza, rural Indonesia, 2005 (2)
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Created using participatory mapping
Shows the sequence of events during
outbreak of highly pathogenic H5N1 avian
influenza in poultry in a small village
Maps
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Initially spread from House 1 to House 5; also in
second village (6) and broiler farm (top right)
Photo credit: Dr Gavin Macgregor-Skinner/USAID
Maps
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Subsequent investigation revealed that
residents of House 1 and households in
second village worked at broiler farm
Probably introduced H5N1 virus into
communities by carrying it home on shoes
and clothing
Geographic Information
Systems
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Geographic information system (GIS): a
computer program designed to store,
manipulate, analyze, and display data in
a geographic context
GIS capabilities are ideal for use in
infectious disease surveillance and
control, outbreak investigation and
response
Geographic Information
Systems

GIS can help:
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Optimize data collection and management
Strengthen data analysis
Strengthen outbreak infrastructure and support
Map epidemic dynamics in near real-time
Quickly plan and target response
Rapidly communicate information
Monitor changes in disease over time
Plan, monitor intervention/eradication programs
Aid emergency preparedness
GIS Example: West Nile Virus
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GIS displays information in map “layers”
Example: West Nile virus
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Street network
Buildings: enclosures for
sentinel species (chicken
coops, horse stalls),
offices, dwellings
Population at risk
Maps of land cover, digital
elevation, precipitation,
temperature, water features,
veterinarians/physicians
GIS Example: West Nile Virus
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After data is entered into GIS tool, you can…
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Maintain surveillance of case-patient locations and
progression of disease for early outbreak detection
Identify areas ideal for mosquito breeding and
apply preventive measures
Predict which populations are vulnerable to
infection based on proximity to breeding grounds
Simulate how an epidemic could evolve given
introduction of infected mosquitoes/birds at
various locations
Determine where to target interventions,
strengthen healthcare resources
Surveillance and GIS Example:
Public Health Mapping Programme
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Developed in 1993 by WHO and UNICEF to
eradicate Guinea worm disease
GIS used to:
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Visualize disease foci
Monitor newly infected or re-infected villages,
Identify populations at risk
Target cost-effective interventions
Monitor eradication efforts
Surveillance and GIS Example:
Public Health Mapping Programme
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Technology developed to control one disease
can enhance control of others
Since Guinea worm project, GIS and mapping
expanded to meet data needs for:
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Onchocerciasis (river blindness)
Blinding trachoma
African trypanosomiasis (sleeping sickness)
Lymphatic filariasis (elephantiasis)
Poliomyelitis
Malaria
Surveillance and GIS Example:
HealthMapper
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Elimination of lymphatic filariasis possible through
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Mass drug administration to those at risk
Promotion of intensive hygiene on affected body parts
Populations at risk, size, location not identified
HealthMapper enabled countries to estimate
prevalence of disease at district level, identify
precise areas to target for mass drug administration
Also tool for standardizing surveillance, monitoring
indicators in different countries and regions (3)
Surveillance and GIS Example:
Roll Back Malaria Partnership
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Global partnership to enable effective, sustainable
action against malaria
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WHO strategy includes prompt treatment with effective
drugs, vector-control methods, preventive treatment in
pregnancy, emergency and epidemic preparedness and
response
Developed GIS to:
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Strengthen surveillance at local level for early detection,
response to epidemics
Complement existing national/international health
monitoring systems
Integrate information on community interventions, control
interventions, private and public health providers,
partner intervention areas, resources
Be accessible at different levels
Surveillance and GIS Example:
US West Nile Virus Surveillance
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CDC developed national surveillance plan for
WNV to monitor spread of infection, provide
national/regional information, identify
regional distribution and incidence of other
arbovirus diseases
GIS used to enhance federal surveillance
system, communicate results to the public
Surveillance and GIS Example:
US West Nile Virus Surveillance
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CDC, US
Geological
Survey
mapped
mosquito,
wild bird,
horse,
human
populations
Tracked in
sentinel
species
(chickens)
2007 U.S. Geologic Survey
Surveillance and GIS Example:
US West Nile Virus Surveillance
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Pennsylvania developed network to combat WNV
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Covers all 67 counties
Includes trapping mosquitoes, collecting dead birds,
monitoring horses, people, chickens
WNV Tracking System: spatially-driven surveillance
program for following, responding to spread of WNV
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Collects information on presence of virus, identifies
mosquito-breeding areas, helps target control efforts
Alerts decision makers of new data via e-mail
Generates, posts detailed maps on secure Web site
Data for public release published on WNV Surveillance
Program Web site (www.westnile.state.pa.us/)
Outbreak Investigation and
GIS
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GIS used to:
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Strengthen data collection, management,
and analysis
Develop early warning systems
Plan and monitor response programs
Communicate large volumes of complex
information in simple, effective way to
decision makers and public
Outbreak Investigation and
GIS Example: Shigellosis
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Fort Bragg, North Carolina, 1997 (4)
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59 cases of Shigella sonnei reported
among military health beneficiaries
Significant number of cases were children
Preliminary investigation did not reveal
associations with daycare or common
location
Outbreak persisted despite education
about hand washing and hygiene
Outbreak Investigation and
GIS Example: Shigellosis
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Imported addresses
of all confirmed
cases into GIS and
mapped onto Fort
Bragg housing areas
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Revealed cluster of
infections on several
streets in one
particular
neighborhood
Outbreak Investigation and
GIS Example: Shigellosis
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Interviews with case families, neighbors
revealed presence of small communal wading
pools in several yards that were frequented
by affected children
Once pools were removed and home-based
information campaigns were initiated, spread
of illness was halted
Outbreak Investigation and
GIS Example: STIs
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GIS also used to map sexually transmitted
infections
Used in Baltimore to map distribution of
syphilis before, during, after outbreak (5)
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Data suggested that disease spread outward
from 2 central cores of infection
Outbreak Investigation and
GIS Example: STIs
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Used to map
distribution of 4
sexually transmitted
infections (chlamydia,
gonorrhea, syphilis,
and HIV infection) in
Wake County, NC (6)
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Found clearly defined
spatially heterogeneous
areas of infection for
different diseases
Global Positioning Systems
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Global positioning systems (GPS) add
function to GIS, increase capabilities
A critical tool for precise identification of
research subjects, locations, distances
to related geographic features
Allow users to locate positions on
electronic map using satellite
technology
Global Positioning Systems
Example: Atrazine Exposure
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RTI International employed GPS-enabled
handheld technology in a National Cancer
Institute study to determine relationship
between exposure to atrazine and distance
from fields where used (7)
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Required field trips to verify locations of
households in study area near corn fields in Illinois
Used HP iPAQ Pocket PC with GPS receiver and
ESRI's ArcPad® software (GIS software for
mapping that allows capture, display, analysis of
geographic information on handheld devices)
Global Positioning Systems
Example: Atrazine Exposure
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Candidate household
addresses geocoded to
street database, loaded
onto ArcPad with aerial
photographs, street
centerline database
Staff used GPS, street names to find approximate
location of households
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Modified original address-matched location (green dots) to actual
location (red dots) based on GPS and rooftops on aerial map
If households not seen on map, GPS coordinate on
street captured
Global Positioning Systems
Example: Atrazine Exposure
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Measured household's distance from corn field where
atrazine used
Concentrations of atrazine in household, in biological
samples from occupants correlated with distance
from atrazine source
Using ArcPad/GPS instead of paper maps
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Allowed quick navigation from household to household
Made repositioning of household locations more accurate
Would have been almost impossible to do under study’s time
constraints without this technology
Precisely measured household locations and precise
distances from households to corn fields provided
higher precision during data analysis
Global Positioning Systems
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Approach could be applied to infectious
disease surveillance and outbreak
investigation and response
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To measure distance to exposure (e.g., water
source with cryptosporidium or farm with hoof and
mouth disease)
Outbreak investigation and response are
time-limited activities: must be done quickly
to have greatest effect
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GIS and GPS can greatly speed field work
Summary
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Spread of disease — especially infectious
disease — is unavoidably spatial
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Infection moves from individual to individual
following network of contacts within population
through local or global transmission
GIS capacity to capture geospatial
information ideally suited for infectious
disease surveillance and control; highly
relevant to meet demands of outbreak
investigation and response
Next issue will show how GIS used to
conduct rapid needs assessments
Additional Resources for GIS
Mapping
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World Health Organization Public Health
Mapping Programme
http://www.who.int/health_mapping/en/
WHO HealthMapper
http://www.who.int/health_mapping/tools/
healthmapper/en/index.html
Roll Back Malaria Partnership
http://www.rbm.who.int/
Further Readings
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Melnick, Alan L. Introduction to geographic
information systems in public health.
Gaithersburg, Md: Aspen Publishers; 2002.
Cromley, Ellen K. GIS and public health. New
York: Guilford Press; 2002.
Moore DA, Carpenter TE. Spatial Analytical
Methods and Geographic Information
Systems: Use in Health Research and
Epidemiology. Epidemiologic Reviews.
1999;21(2):143-160.
References
1.
2.
3.
4.
Tufte ER, The Visual Display of Quantative Information. 2nd ed.
Cheshire, CT: Graphics Press, LLC; 1983:176.
Macgregor-Skinner G. Avian influenza H5N1: Getting our ducks
in a row. Presentation at: 5th Annual “One Medicine”
Symposium; December 12-13, 2007; Durham, NC.
Brooker S, Beasley M, Ndinaromtan M, et al. Use of remote
sensing and a geographical information system in a national
helminth control programme in Chad. Bulletin of the World
Health Organization. 2002;80:783-789.
McKee KT, Shields TM, Jenkins PR, Zenilman JM, Glass GE.
Application of a geographic information system to the tracking
and control of an outbreak of shigellosis. Clin Infect Dis.
2000;31:728-733.
References
4.
5.
6.
7.
Gesink Law DC, Bernstein KT, Serre ML, et al. Modeling a
syphilis outbreak through space and time using the Bayesian
maximum entropy approach. Ann Epidemiol. 2006;16:797-804.
Law DCG, Serre ML, Christakos G, Leone PA, Miller WC. Spatial
analysis and mapping of sexually transmitted diseases to
optimise intervention and prevention strategies. Sex Transm
Infect. 2004;80:294-299.
ArcPad—Mobile GIS software for field mapping applications.
ESRI Web site. http://www.esri.com/software/arcgis/arcpad/.
Accessed April 23, 2008.
Holmes EE. Basic epidemiological concepts in a spatial context.
In: Tilman D, Kareiva P, eds. Spatial Ecology : The Role of Space
in Population Dynamics and Interspecific Interactions. Princeton,
NJ: Princeton University Press; 1997:111-136.

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