Mapping for Surveillance and Outbreak Investigation.

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 AssociateDepartment of Epidemiology, University of North Carolina at Chapel Hill

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

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

Maps Earliest documented

epidemiologic study relied on mapping

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

Most noted example of maps to convey complicated statistical information comes from outside public health (1) 1869 map of French army’s march to

and retreat from Moscow Displays multivariate data (army size,

direction, geographic location, temperature, and time)

Maps Line widths show size of French army on

advance to Moscow (tan) and retreat (black) Chart below lines plots temperature

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

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

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

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

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

GIS Example: West Nile Virus

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

GIS displays information in map “layers”

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

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

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

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)

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

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


CDC, US Geological Survey mapped mosquito, wild bird, horse, human populations

Tracked in sentinel species (chickens)

2007 U.S. Geologic Survey


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/)

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

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


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


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

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

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

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

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)

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

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

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 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

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

Additional Resources for GIS Mapping World Health Organization Public Health

Mapping Programmehttp://www.who.int/health_mapping/en/

WHO HealthMapper

http://www.who.int/health_mapping/tools/ healthmapper/en/index.html

Roll Back Malaria Partnershiphttp://www.rbm.who.int/

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. 1999;21(2):143-160.

References1. Tufte ER, The Visual Display of Quantative Information.

2nd ed. Cheshire, CT: Graphics Press, LLC; 1983:176.2. 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. 2002;80:783-789.

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. 2000;31:728-733.

References4. 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.

5. 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.

6. ArcPad—Mobile GIS software for field mapping applications. ESRI Web site. http://www.esri.com/software/arcgis/arcpad/. Accessed April 23, 2008.

7. 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.

Mapping for Surveillance and Outbreak Investigation.

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