&EPA
United States
Environmental Protection
Agency
Public Health Surveillance Primer
For Water Quality Surveillance and Response Systems
Office of Water (MC 140)
EPA817-B-15-002D
May 2015
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Public Health Surveillance Primer
Introduction
A Water Quality Surveillance and Response System (SRS) provides a systematic framework for
enhancing distribution system monitoring activities to detect emerging water quality issues and respond
before they become problems. An SRS consists of six components grouped into two operational phases,
surveillance and response. The surveillance components are designed to provide timely detection of
water quality incidents in drinking water distribution systems and include: Online Water Quality
Monitoring, Enhanced Security Monitoring, Customer Complaint Surveillance and Public Health
Surveillance. The response components include Consequence Management and Sampling & Analysis,
which support timely response actions that minimize the consequences of a contamination incident. The
Water Quality Surveillance and Response System Primer provides a brief overview of the entire system
(USEPA, 2015a).
This document provides an overview of the Public Health Surveillance (PHS)
component of an SRS. It presents basic information about the goals and
objectives of PHS in the context of an SRS. This primer covers the following
four topics:
• Topic 1: What is PHS?
• Topic 2: What are the major design elements of PHS?
• Topic 3: What are common design goals and performance objectives
for PHS?
• Topic 4: What are cost-effective approaches for PHS?
Topic 1: What is PHS?
PHS is the ongoing, systematic collection, analysis and interpretation of public health data. The main
goal of PHS is to detect changes in the health status of a community in sufficient time to allow for
intervention to mitigate the consequences of an emerging threat to public health. Figure 1 shows two
broad types of PHS, case-based and syndromic surveillance. Case-based surveillance involves an
assessment of public health
status based on in-person
observation of individual
patients. Syndromic
surveillance involves the
monitoring of aggregated
public health data. Each
type of surveillance provides
community-level health
information. Public health
partners can increase the
potential to detect a change
in the health status of a
community by conducting
both case-based and
syndromic surveillance.
Public Health Surveillance
Case-based
Surveillance
In-person individual
assessment conducted
by healthcare workers,
or via calls received by
Poison Control Centers
and healthcare hotlines
Syndromic Surveillance
Monitoring of public health data
that is available earlier than clinical
diagnosis or lab test results
Manual
Surveillance
Manual analysis of
public health data
conducted by health
departments or Poison
Control Centers
Automated
Surveillance
Automated analysis of
public health data
conducted using
statistical algorithms
or software tools
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Public Health Surveillance Primer
PHS is unique in that it is generally monitored by public health partners, whereas other SRS components
are monitored by water utility personnel. Communication between water utilities and public health
partners has often been insufficient to provide timely detection and response to waterborne disease
outbreaks. Incorporating PHS into an SRS helps ensure that data acquisition, analysis and information
sharing is coordinated between the drinking water utility and public health partners, resulting in earlier
detection of possible drinking water contamination incidents.
Topic 2: What are the major design elements of PHS?
The major design elements for PHS are shown in Figure 2 and described under the remainder of this
topic.
Integration of
PHS
Capabilities
Emergency
Medical Svcs.
Communication
and
Coordination
Alert
Investigation
Procedures
Notification
Figure 2. PHS Design Elements
Hospital
Local Public
Health
Poison
Control
Strengthen
Partnerships
Regular
Engagement
Information
Sharing
Documentation
Integration of Public Health Surveillance Capabilities
A well designed PHS component is able to provide both timely and detailed information to investigators.
Potential public health datastreams include:
• 911 calls
• Emergency medical services runs
• Poison control center calls
• National Poison Data System
• Emergency department data
• Over-the-counter medication sales
• Direct observation by healthcare professionals
For purposes of an SRS, these datastreams are analyzed in order to detect patterns that may signal a
public health incident that could be related to drinking water contamination. Many of these datastreams
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Public Health Surveillance Primer
include geographic identifiers that can be used to investigate spatial clustering of cases. Factors to
consider when deciding which datastreams to leverage for PHS may include:
• Availability of datastreams
• Frequency of data analysis
• Level of confidence in the datastream as an indicator of illness or disease in the population
• Types of contamination incidents that could be identified through this datastream
• Availability of methods to automate data collection and analysis
• Availability of underlying case data, such as patient information such as symptoms, age and
location of the exposure, during alert investigations
Ideally, PHS should include surveillance of datastreams that would provide detection capability for
contaminants with both rapid and delayed symptom onset, thus covering a wide range of potential
contaminants.
PHS Communication and Coordination
Communication and coordination involves identifying relevant public health partners, engaging them
during planning activities, and working with them during the investigation of PHS alerts in a manner that
facilitates efficient data sharing and consensus building. An SRS can only be successful if the water
utility and public health partners communicate and share information. Public health experts provide
information that might not otherwise be available to utilities and which is useful for investigating possible
water contamination incidents.
PHS Alert Investigation Procedures
PHS alert investigation procedures describe how public health partners use PHS datastreams and other
resources to investigate PHS alerts and determine whether or not they are caused by possible drinking
water contamination. In general, PHS alert investigations are conducted jointly by the utility and public
health partners. Figure 3 illustrates how an investigation into a possible water contamination incident can
begin with either a PHS alert or a utility alert.
5. Activate Utility
Consequence
Management Plan
5. Activate Utility
Consequence
Management Plan
4. Notify
Public
Health
2. Notify
Utility
Figure 3. Example of a PHS Alert Investigation Process
In the example shown in Figure 3, the investigation is assumed to begin with the generation of a PHS
alert, and illustrates the communication pathways between the utility and public health agencies during
the investigation. The numbered steps in this figure are briefly described below:
1. The investigation begins following receipt of a PHS alert generated through one of the
surveillance methods. Public health personnel review underlying case data related to the alert in
order to determine whether the alert is valid.
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Public Health Surveillance Primer
2. If public health partners determine that the PHS alert is valid, and if investigators cannot rule out
possible water contamination as the cause of the alert, the public health investigator notifies the
water utility.
3. Once notified of the PHS alert, the utility reviews data from other SRS components, such as
customer complaint surveillance, along with other utility information that can help investigators
determine whether or not the PHS alert is related to drinking water quality.
4. The utility shares the results of their investigation with public health partners. If information
provided by the utility is sufficient to rule out drinking water contamination, the investigation is
closed.
5. If contamination cannot be ruled out following the utility investigation, water contamination is
considered possible and the consequence management plan is activated.
Topic 3: What are common design goals and performance objectives
for PHS?
The design goals and performance objectives established for PHS by the utility and its public health
partners provide the basis for the design of an effective component.
PHS Design Goals
Design goals are the specific benefits that utilities expect to achieve by implementing PHS. A
fundamental design goal of an SRS is the ability to detect and respond to water quality anomalies in the
distribution system. In addition to this fundamental SRS design goal, other PHS-specific design goals
such as improved coordination between the utility and public health partners can be realized. Examples
of common PHS design goals are listed in Table 1.
Table 1. Examples of Common PHS Design Goals
Design Goal
Detect water contamination incidents
Increase awareness of the
relationships between public health
protection and drinking water quality
Monitor for other community health
issues of interest
Description
Training healthcare providers and creating systems to monitor for
symptoms related to waterborne disease outbreaks, such as those
resulting from Cryptosporidium and norovirus infections. Training is also
provided to improve recognition of exposures to toxic chemicals via
contaminated drinking water.
Establishing a joint public health and utility workgroup will encourage
collaboration to effectively address water quality issues that may impact
public health.
Beyond possible drinking water contamination, PHS systems used in an
SRS can support other public health goals such as monitoring for low-
level but potentially harmful background environmental exposures.
PHS Performance Objectives
Performance objectives are measurable indicators of how well the SRS meets the design goals established
by the utility. Throughout design, implementation and operation of the SRS or its components, the utility
can use performance objectives to evaluate the added value of each capability, procedure or partnership.
While specific performance objectives should be developed by each utility in the context of its unique
design goals, general performance objectives for an SRS were defined in the Water Quality Surveillance
and Response System Primer (USEPA, 2015a) and are further described in the context of PHS as follows.
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Public Health Surveillance Primer
• Incident coverage: Detect and respond to abroad spectrum of water quality incidents. PHS is
limited to detection of contaminants that result in illness. It should be noted that while some
contaminants do not result in short or long term health impacts, they may elicit physiological
effects such as nausea or headaches if they have strong aesthetic characteristics such as a foul
odor. Thus, these contaminants may prompt exposed individuals to seek healthcare, and
potentially generate a PHS alert.
• Spatial coverage: Achieve spatial coverage of the entire distribution system. Theoretically, PHS
has the ability to cover every customer in the distribution system, but the actual spatial coverage
achieved by PHS may be impacted by the degree to which public health data can be effectively
collected in real-time throughout the distribution system.
• Timeliness of detection: Detect public health incidents in sufficient time for effective response.
This performance objective is impacted by how quickly data is available for analysis and how
often the analysis is performed.
• Alert occurrence: Minimize the number of invalid alerts while maintaining the ability of the
system to detect true alerts based on pre-established thresholds of syndrome and case frequencies.
This performance objective is primarily impacted by the accuracy of data generated and the data
analysis method(s) used.
• Sustainability: Maintain surveillance systems and relationships between the utility and public
health partners. The effectiveness of PHS requires maintenance of relationships and
communication pathways across multiple agencies.
Topic 4: What are cost-effective approaches for PHS?
Utilities can take the following simple steps to develop the foundation for PHS:
• Meet with local public health partners to establish relationships, exchange contact information,
and learn how public health partners could support detection of and response to contaminated
drinking water. USEPA has developed a Public Health Assessment Interview Form that utilities
can use to engage their local public health partners (USEPA, 2015b).
• Evaluate PHS datastreams currently monitored by public health partners to determine if they have
the potential to provide timely detection of contaminated drinking water.
• Establish procedures for the j oint utility and public health investigation of PHS alerts that might
be indicative of contaminated drinking water.
Next Steps
Visit the Water Quality Surveillance and Response Website at http://water.epa.gov/infrastructure
/watersecuritv/lawsregs/initiative.cfm for more information about SRS practices. The Website contains
guidance and tools that will help a utility to enhance surveillance and response capabilities, as well as
case studies that share utility experiences with SRS implementation and operation.
References
USEPA. (2015a). Water Quality Surveillance and Response System Primer, 817-B-15-002.
USEPA. (2015b). Public Health Surveillance Assessment Interview Form, 817-B-15-001.
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