Automated surveillance of 911 call data for detection of possible water contamination incidents

<p>Abstract</p> <p>Background</p> <p>Drinking water contamination, with the capability to affect large populations, poses a significant risk to public health. In recent water contamination events, the impact of contamination on public health appeared in data streams monitoring health-seeking behavior. While public health surveillance has traditionally focused on the detection of pathogens, developing methods for detection of illness from fast-acting chemicals has not been an emphasis.</p> <p>Methods</p> <p>An automated surveillance system was implemented for Cincinnati's drinking water contamination warning system to monitor health-related 911 calls in the city of Cincinnati. Incident codes indicative of possible water contamination were filtered from all 911 calls for analysis. The 911 surveillance system uses a space-time scan statistic to detect potential water contamination incidents. The frequency and characteristics of the 911 alarms over a 2.5 year period were studied.</p> <p>Results</p> <p>During the evaluation, 85 alarms occurred, although most occurred prior to the implementation of an additional alerting constraint in May 2009. Data were available for analysis approximately 48 minutes after calls indicating alarms may be generated 1-2 hours after a rapid increase in call volume. Most alerts occurred in areas of high population density. The average alarm area was 9.22 square kilometers. The average number of cases in an alarm was nine calls.</p> <p>Conclusions</p> <p>The 911 surveillance system provides timely notification of possible public health events, but did have limitations. While the alarms contained incident codes and location of the caller, additional information such as medical status was not available to assist validating the cause of the alarm. Furthermore, users indicated that a better understanding of 911 system functionality is necessary to understand how it would behave in an actual water contamination event.</p

Analysis of Healthcare Seeking Behavior

This paper describes analyses of health seeking behaviors from two surveillance datastreams: Poison Control Center (PCC) calls and Emergency Department (ED) visit records. These analyses were conducted in order to quantify behaviors following the development of symptoms after water contamination exposure and to understand  the motivation, decision-making and timing behind healthcare seeking behaviors

Public Health Surveillance in Pilot Drinking Water Contamination Warning Systems

OBJECTIVE: This paper describes the lessons learned from operation and maintenance of the public health surveillance (PHS) component of five pilot city drinking water contamination warning systems (CWS) including: Cincinnati, New York, San Francisco, Philadelphia, and Dallas. INTRODUCTION: The U.S. Environmental Protection Agency (EPA) designed a program to pilot multi-component contamination warning systems (CWSs), known as the “Water Security initiative (WSi).” The Cincinnati pilot has been fully operational since January 2008, and an additional four pilot utilities will have their own, custom CWSs by the end of 2012. A workshop amongst the pilot cities was conducted in May 2012 to discuss lessons learned from the design, implementation, operation, maintenance, and evaluation of each city’s PHS component. METHODS: When evaluating potential surveillance tools to integrate into a drinking water contamination warning system, it is important to consider design decisions, dual use applications/considerations, and the unique capabilities of each tool. The pilot cities integrated unique surveillance tools, which included a combination of automated event detection tools and communication and coordination procedures into their respective PHS components. The five pilots performed a thorough, technical evaluation of each component of their CWS, including PHS. RESULTS: Four key lessons learned were identified from implementation of the PHS component in the five pilot cities. First, improved communication and coordination between public health and water utilities was emphasized as an essential goal even if it were not feasible to implement automated surveillance systems. The WSi pilot project has helped to strengthen this communication pathway through the process of collaborating to develop the component, and through the need to investigate PHS alerts. Second, the approximate location of specific cases associated with PHS alerts was found to be an essential feature that allowed a cross-comparison to water pressure zones when attempting to locate the source of possible contamination. More specific location data (e.g., latitude and longitude) leads to a more efficient investigation, however, just narrowing the case location down to a specific hydraulic region within the water distribution system is extremely useful. Third, the ability to quickly visualize spatial distribution of cases via a visual interface was reported to be valuable to investigators during alert investigations. Most pilots implemented a CWS dashboard, in the form of a central graphical display, which presents the alerts and was used by the water utility and public health to obtain an understanding of geospatial relationships between cases, alerts and water pressure zones. Finally, public health and water utility representatives from several of the WSi pilots acknowledged that their automated surveillance tools currently have limited capabilities for detection of chemical contaminants (which may result in a sudden onset of symptoms), with the main deficiency being the timeliness of the alerts relative to the window of opportunity to respond in a meaningful and effective manner. While they currently focus on detection of traditional waterborne diseases, these tools could potentially be adapted to also detect chemical contaminants. CONCLUSIONS: The results of the pilots have demonstrated that it is important to construct and formalize standard operating procedures, so that public health personnel and water utilities have a standard communication protocol. As a basic step to a PHS component, it is important to establish a relationship between utilities and public health. In addition to the efforts of the WSi pilots, research is currently being conducted by the U.S. EPA to analyze health seeking behavior of symptomatic individuals, because all PHS tools rely on data generated from behavior pursued by the affected population during a public health incident. Results from analysis of both emergency department data and poison control center follow-up phone data are currently underway

Public Health Surveillance in Pilot Drinking Water Contamination Warning Systems

The U.S. Environmental Protection Agency (EPA) designed a program to pilot multi-component contamination warning systems (CWSs), known as the Water Security initiative. The goal of the EPA's Water Security initiative is to demonstrate the feasibility and benefits of implementing a CWS, both for detecting contamination incidents as well as improving the day-to-day operation (USEPA WaterSentinel System Architecture, 2005). The Cincinnati pilot has been fully operational since January 2008, and an additional four pilot utilities are in the process of testing and evaluating their own CWSs which have been designed and implemented in Philadelphia, New York City, Dallas, and San Francisco. To ensure long-term sustainability of the PHS component, it is important to understand lessons learned from use of tools, along with communication challenges between public health and the local water utility