Mapping for Surveillance and Outbreak Investigation

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Mapping for Surveillance and Outbreak
Investigation
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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

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Goals

• 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

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Mapping for Surveillance and Outbreak
Investigation

• Maps are commonly used in epidemiology to present
  complicated information succinctly and clearly
• This issue discusses
• 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

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Maps

• Earliest documented epidemiologic study relied on
  mapping
• Dr. John Snows investigation of cholera
  outbreak, London, 1854
• Used maps and statistical data to trace source of
  outbreak to public water pump on Broad Street 

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Maps

• Most noted example of maps to convey complicated
  statistical information comes from outside public
  health (1)
• 1869 map of French armys march to and retreat
  from Moscow
• Displays multivariate data (army size, direction,
  geographic location, temperature, and time)

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Maps

• Line widths show size of French army on advance
  to Moscow (tan) and retreat (black)
• Chart below lines plots temperature

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Maps

• Map created during disease surveillance and
  response activities around avian influenza, rural
  Indonesia, 2005 (2)
• Created using participatory mapping
• Shows the sequence of events during outbreak of
  highly pathogenic H5N1 avian influenza in poultry
  in a small village 

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Maps

• 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
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Maps

• 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

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Geographic Information Systems

• 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

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Geographic Information Systems

• GIS can help
• 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

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GIS Example West Nile Virus

• GIS displays information in map layers

• Example West Nile virus
• 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

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GIS Example West Nile Virus

• After data is entered into GIS tool, you can
• 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

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Surveillance and GIS Example Public Health
Mapping Programme

• Developed in 1993 by WHO and UNICEF to eradicate
  Guinea worm disease
• GIS used to
• Visualize disease foci
• Monitor newly infected or re-infected villages,
• Identify populations at risk
• Target cost-effective interventions
• Monitor eradication efforts

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Surveillance and GIS Example Public Health
Mapping Programme

• Technology developed to control one disease can
  enhance control of others
• Since Guinea worm project, GIS and mapping
  expanded to meet data needs for
• Onchocerciasis (river blindness)
• Blinding trachoma
• African trypanosomiasis (sleeping sickness)
• Lymphatic filariasis (elephantiasis)
• Poliomyelitis
• Malaria

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Surveillance and GIS Example HealthMapper

• Elimination of lymphatic filariasis possible
  through
• 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)

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Surveillance and GIS Example Roll Back Malaria
Partnership

• Global partnership to enable effective,
  sustainable action against malaria
• WHO strategy includes prompt treatment with
  effective drugs, vector-control methods,
  preventive treatment in pregnancy, emergency and
  epidemic preparedness and response
• Developed GIS to
• 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

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Surveillance and GIS Example US West Nile Virus
Surveillance

• 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

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Surveillance and GIS Example US West Nile Virus
Surveillance

• CDC, US Geological Survey mapped mosquito, wild
  bird, horse, human populations
• Tracked in sentinel species (chickens)

2007 U.S. Geologic Survey
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Surveillance and GIS Example US West Nile Virus
Surveillance

• Pennsylvania developed network to combat WNV
• 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
• 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/)

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Outbreak Investigation and GIS

• GIS used to
• 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

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Outbreak Investigation and GIS Example
Shigellosis

• Fort Bragg, North Carolina, 1997 (4)
• 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

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Outbreak Investigation and GIS Example
Shigellosis

• Imported addresses of all confirmed cases into
  GIS and mapped onto Fort Bragg housing areas
• Revealed cluster of infections on several streets
  in one particular neighborhood

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Outbreak Investigation and GIS Example
Shigellosis

• 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

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Outbreak Investigation and GIS Example STIs

• GIS also used to map sexually transmitted
  infections
• Used in Baltimore to map distribution of syphilis
  before, during, after outbreak (5)
• Data suggested that disease spread outward from 2
  central cores of infection

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Outbreak Investigation and GIS Example STIs

• Used to map distribution of 4 sexually
  transmitted infections (chlamydia, gonorrhea,
  syphilis, and HIV infection) in Wake County, NC
  (6)
• Found clearly defined spatially heterogeneous
  areas of infection for different diseases 

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Global Positioning Systems

• 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

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Global Positioning Systems Example Atrazine
Exposure

• 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)
• 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)

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Global Positioning Systems Example Atrazine
Exposure

• 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
• 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

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Global Positioning Systems Example Atrazine
Exposure

• 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
• Allowed quick navigation from household to
  household
• Made repositioning of household locations more
  accurate
• Would have been almost impossible to do under
  studys time constraints without this technology
• Precisely measured household locations and
  precise distances from households to corn fields
  provided higher precision during data
  analysis

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Global Positioning Systems

• Approach could be applied to infectious disease
  surveillance and outbreak investigation and
  response
• 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
• GIS and GPS can greatly speed field work

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Summary

• Spread of disease especially infectious disease
  is unavoidably spatial
• 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

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Additional Resources for GIS Mapping

• 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/ 

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Further Readings

• 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. 199921(2)143-160.

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References

1. Tufte ER, The Visual Display of Quantative
   Information. 2nd ed. Cheshire, CT Graphics
   Press, LLC 1983176.
2. 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.
3. 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. 200280783-789.
4. 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. 200031728-733.

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References

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   Modeling a syphilis outbreak through space and
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3. ArcPadMobile GIS software for field mapping
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4. Holmes EE. Basic epidemiological concepts in a
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