BACKGROUND
The use of mapping to identify the source of an infectious disease outbreak is well documented in history.Reference Snow 1 However, geographic information systems (GIS) have only emerged in the past few decades as an important technological aspect of epidemiology in public healthReference Musa, Chiang and Sylk 2 and more specifically for surveillance and control of infectious disease outbreaks.Reference Smith, Le Comber, Fry, Bull, Leach and Hayward 3 Legionnaires’ disease is caused by inhalation of aerosolized Legionella bacteria from an environmental water source. The use of GIS to identify the location of higher-risk water sources during outbreaks is becoming more common.Reference Bull, Hall, Leach and Robesyn 4
Despite the growing use of GIS globally,Reference Smith, Le Comber, Fry, Bull, Leach and Hayward 3 there is no common system, process, or guideline that Public Health Unit (PHU) staff in New South Wales (NSW), Australia, can use to inform Legionnaires’ disease control activity. In May 2016, the Sydney Local Health District (SLHD) initiated a Legionnaires’ disease cluster investigation,Reference Dowsett, Quinn and Gupta 5 and one of the key lessons from this investigation was the need to train staff and develop and implement standard processes for use of GIS in the control of infectious disease outbreaks.Reference Quinn, Johnstone, Najjar and Cains 6 SLHD PHU developed a desktop exercise to test the capability of NSW PHU staff in using GIS to inform an outbreak investigation (using the SLHD Legionella cluster as the example). Eleven staff members from 4 PHUs in metropolitan Sydney, NSW, participated in the exercise, held over 2 half-days on April 27 and 28, 2017. The exercise was evaluated to capture any key lessons for future use of GIS within NSW.
EXERCISE PLAN
Exercise Objectives
The objectives of the exercise were as follows:
1. To gather feedback on the use of different GIS across several PHUs in Sydney;
2. To test staff capability in:
a. geocoding data;
b. producing multi-layered maps—that is, including disease exposure locations, case residence, and location of cooling towers, with buffer zones around common exposure areas; and
c. reporting GIS data in a situational report with a map and list of high-risk water sources, to inform environmental health control measures.
3. To document lessons learnt regarding the use of GIS in NSW.
Exercise Scope and Scenario
At least 1 staff member from each PHU was invited to participate and was required to have skills in mapping and producing situational reports. In preparation, 2 teleconferences were held and an exercise outline was shared with participants. The scenario mimicked the SLHD PHU Legionnaires’ disease cluster investigation,Reference Dowsett, Quinn and Gupta 5 but fitted into 2 half-days (3 hours per day) with action to identify a cluster (ie, one or more Legionnaires’ disease cases reporting a common exposure within 100 m over a 3-month period) and high-risk water sources for sampling as per NSW Health guidelines. 7 The desktop exercise was conducted with time-limited components to reflect the urgency and need for timely GIS data to inform the investigation; however, recommended field actions were nominal only.
EXERCISE EVALUATION
Evaluation tools included an audit checklist of PHU exercise outputs, with outputs for each assigned task assessed as fully achieved, partially achieved, or not completed. A hot debrief meeting collected feedback around (1) what went well? (2) what didn’t go so well? and (3) what could we improve for next time? An online semi-structured survey developed using REDCapReference Harris, Taylor, Thielke, Payne, Gonzalez and Conde 8 was used to collect information on the level of agreement on the effectiveness of the design and operations of the exercise (Likert scale from strongly agree to strongly disagree), as well as the level of difficulty regarding the assigned tasks (Likert scale from very easy to very difficult).
Of the 11 participants, 10 completed the online survey (91% response rate). At least 8/10 participants agreed that sufficient pre-exercise information was provided, assigned tasks were clear, sufficient data were provided to complete tasks, and the scenario progression was realistic. Participants reported that existing skill deficits in the use of GIS for required tasks meant that completion of the exercise took longer than they had anticipated. Participants suggested that pre-exercise webinars would be helpful for preparedness—for example, including an overview of mapping tasks. In addition, real-life work issues took precedence over the exercise, highlighting the need to ensure that participants have agreement on their own protected time to complete the exercise.
Lessons Learnt: The Application of GIS to Inform Legionella Control Activity
No common system: the multitude of geocoding software and GIS
Four different geocoding programs were used by participants. Three were open-source software products and 1 was an application designed and managed by NSW Health. In contrast, the majority of participants used only 1 GIS application, ArcGIS explorer. An array of GIS platforms are available, and the functionality and inter-operability of software is critical.Reference Carroll, Au, Detwiler, Fu, Painter and Abernethy 9 Several authorsReference Musa, Chiang and Sylk 2 , Reference Carroll, Au, Detwiler, Fu, Painter and Abernethy 9 have argued that different software is needed to produce, map, and analyze geographic data. Each of these data manipulation processes have resource implications in terms of cost of software and training required.Reference Carroll, Au, Detwiler, Fu, Painter and Abernethy 9
Specific skills required to use GIS for Legionnaires’ disease control activity
Over half of the exercise participants reported some level of difficulty with producing multi-layered maps and producing lists of water sources for inspection to inform field investigations according to guidelines. 7 Participants reported issues with the following skills: (1) mapping lines (ie, mapping the travel routes of cases), (2) creating buffer zones, and (3) systematically identifying and extracting data on points lying within overlapping zones, which allows the water sources of concern to be identified. These particular GIS skills are essential for Legionnaires’ disease control activity,Reference Bull, Hall, Leach and Robesyn 4 as per NSW Health guidelines, 7 but require practice for timely outbreak response.Reference Jansà, Caylà and Ferrer 10
In addition, participants mapped the buffer zones differently (eg, mapping concentric buffer zones around every single exposure location vs maps with buffer zones around only the most common exposure locations across all cases) and hence produced slightly different lists of water sources to inform field investigations, indicating the need for a common protocol to guide geospatial analysis of data during outbreaks in NSW. Although most participants had some experience with GIS, none had applied GIS in a real-time outbreak scenario and therefore not anticipated the level of technical skill required to complete tasks, reinforcing the importance of regular exercises like this one.
The growing need and interest to develop staff capability to use the GIS in NSW, Australia
All participants agreed in the online survey that the exercise was useful in testing their capabilities in utilizing GIS in an outbreak scenario. Given the growing evidence of the utility of GIS in outbreak surveillance and control,Reference Smith, Le Comber, Fry, Bull, Leach and Hayward 3 , Reference Carroll, Au, Detwiler, Fu, Painter and Abernethy 9 there is great scope and interest in developing a skilled workforce to routinely use GIS for real-time outbreak control activity in NSW.
Improving staff capability through education and training
Some participants reported logistical constraints during the exercise, such as only having 1 computer set up with the GIS software and geocoding applications and only 1 staff member in their PHU with skills or experience in using GIS. Clearly, having sufficient IT infrastructure and number of staff members trained with a minimum skill level in the use of GIS is critical for resilient and rapid responses to disease outbreaks.Reference Carroll, Au, Detwiler, Fu, Painter and Abernethy 9 , Reference Nhavoto and Gronlund 11
DISCUSSION
This exercise demonstrated that training in the use of GIS by running a real-life outbreak scenario is critical to the development of capacity within a public health network to use the technology for infectious disease control. The exercise evaluation pointed toward the need for a common GIS and associated tools, regular education and training, and guidelines to support the consistent and collaborative use of GIS for infectious disease epidemiology in NSW.
Despite growing evidence of the use of GIS for infectious disease outbreak epidemiologyReference Smith, Le Comber, Fry, Bull, Leach and Hayward 3 and in particular for Legionnaires’ disease outbreak control,Reference Bull, Hall, Leach and Robesyn 4 there is no widespread uptake and translation of this technology and knowledge into public heath practice across NSW. Globally, authorsReference Smith, Le Comber, Fry, Bull, Leach and Hayward 3 , Reference Carroll, Au, Detwiler, Fu, Painter and Abernethy 9 have reported the need for (i) easily accessible and reliable geographic data (eg, up-to-date geocoded lists of cooling towers); (ii) a web-accessible, secure, and inter-operable GIS that can provide the functionality users desire; and (iii) usability evaluation and exercises that promote system evolution and resilience for sustained effective use.
State-wide access and use of geospatial data is expected to improve in NSW as the NSW Location and Intelligence Strategy is implemented. 12 NSW Health is also planning to pilot the state-wide use of an ArcGIS server platform for health protection purposes, including infectious disease epidemiology, to enable secure, coordinated access to a single GIS for public health staff in NSW. The pilot will include a package of user needs evaluation, education and training materials, and exercises to promote user-based development of the system.Reference Dubowitz, Williams and Steiner 13 , Reference Reeder, Turner and Demiris 14
This exercise was limited in scope and hence in testing the technical capability of staff members to perform any statistical cluster detection or other methods for spatial analysis of data. However, authors have identified a limited uptake and lack of consistency in the approach to spatial analysis with regard to infectious disease outbreaks.Reference Smith, Le Comber, Fry, Bull, Leach and Hayward 3 , Reference Bull, Hall, Leach and Robesyn 4 Therefore, guidelines on the use of GIS in the spatial analysis of infectious disease outbreaks,Reference Smith, Le Comber, Fry, Bull, Leach and Hayward 3 in particular Legionnaires’ disease,Reference Bull, Hall, Leach and Robesyn 4 , Reference Walser, Gerstner, Brenner, Höller, Liebl and Herr 15 would enable the consistent identification and risk assessment of the time, place, and person characteristics of outbreaks in NSW. Furthermore, the critical interpretation of spatial data to inform field investigations was only tested indirectly through submission of a situational report during the exercise, with 3 of 4 PHUs fully meeting this task.
CONCLUSIONS
This exercise identified an interest and potential gap in the use of GIS for infectious disease outbreak control in NSW. It highlighted that introduction of any new IT system and process across a network of people must be accompanied by ongoing education, training, exercises, and the establishment of standard guidelines for spatial analysis, in NSW and perhaps Australia, if the technology is to be used successfully and consistently for outbreak control activity.
Acknowledgments
The authors gratefully acknowledge the Sydney Local Health District Clinical Research Centre who host REDCap, a secure online application for data capture used in the evaluation of this exercise. The authors would also like to thank Nepean Blue Mountains, Western Sydney, South Western Sydney, and South Eastern Sydney Public Health Units for their participation in the exercise.
