911 call centers, poison control centers, or information on school attendance
(Lesesne et al., working paper). Following the Al Qaeda terrorist attacks
and the subsequent anthrax exposures in the fall of 2001, the federal gov-
ernment vastly enhanced the amount of funding available to support syn-
dromic surveillance systems. As of 2008, approximately 54 states, counties,
or municipalities had implemented some form of syndromic surveillance
system (Lesesne et al., working paper).
Syndromic surveillance systems were originally envisioned as early warn-
ing systems to detect bioterrorist attacks, acts of sabotage, emerging infec-
tions such as pandemic influenza, or contamination of the food or water
supply. Policy makers feared that traditional surveillance systems—which
often rely on weekly, monthly, or even quarterly reports from participat-
ing surveillance sites—would be too slow to detect rapidly emerging health
trends. In theory, by monitoring near- to real-time syndromic information,
health threats could be detected earlier, and this additional time could be
used to contain the damage of the health threat.
However, early warning represents only one possible use for syndro-
mic surveillance systems and traditional surveillance systems may be just
as timely as syndromic surveillance systems in detecting extreme health
events because providers are motivated to report these events to health
departments. Even when syndromic surveillance systems provide early
detection, these signals may be missed or misinterpreted. For example,
the Google Flu Trends system could have provided early detection of the
Mexican swine flu outbreak in the spring of 2009, except that it was not
focused on Mexico (Madrigal, 2009). Furthermore, it is unclear whether
early syndromic detection could be translated into appropriately vigor-
ous policy action, given the difficulties in motivating appropriate outbreak
responses even in the face of existing traditional surveillance information.
In practice, the information from syndromic surveillance systems is far
more often used to enhance the day-to-day situation awareness of pub-
lic health professionals than to provide early warning of previously unde-
tected health threats.
Situation awareness (see Chapter 3) refers to the mental ability to com-
prehend the dynamics of a situation within a finite area of space and time.
Situation awareness has been subdivided into three basic concepts: (1) percep-
tion of the basic problem or challenge, (2) comprehension or understanding
of the mechanisms underlying the problem, and (3) projection of information
or the ability to forecast future events or changes (Endsley 2000). Syndromic
surveillance systems are potentially most valuable in enhancing comprehen-
sion of how a health threat is manifesting itself in a specific context over time
and in helping to predict where the health threat is most likely to spread in