Biology Reference
In-Depth Information
officials viewed the data from the CDC program as less useful than that
from their own systems. The common refrain among many local officials
was that their input and needs were not considered when the BioSense
program was being developed. This lesson for system design is telling.
Officials assumed that the objective of the BioSense surveillance system
was to design a federally operated and centralized operation first to pro-
vide enhanced capability for “early detection,” and later—once this objec-
tive could not be achieved—to provide “situation awareness.” The point
that was missed, however, was that the overall objective in designing the
BioSense program needed to be guided by appropriate and continuous
input from key stakeholders such as state and local health officials. The
objective of the BioSense program should have been to create a system that
enhanced the capacity of these stakeholders to perform their jobs within
their own jurisdictions, not simply to provide data feeds to a federal agency
that lacked capacity and clear vision to amplify their utility.
17.3.2 Conducting Surveillance for emerging Threats
When a public health official is tasked with responding to a novel health
threat, his or her institution typically dispatches personnel to gather clinical,
observational, laboratory, and environmental information as well as sam-
ples. Conducting surveillance for emerging threats is a particularly vexing
issue, with many unforeseen challenges (Wetterhall 1996), but monitoring
and investigating these threats can be made more effective and efficient by
considering the following three tenets:
1. Focus the investigation on the basis of usual routes of exposure for a
known pathogen:
In the ideal world of public health, the practicing epidemiologist
in the local health department facing an outbreak of disease in the
community will have at his or her disposal a diagnostic laboratory
test with perfect attributes—100% sensitivity (to detect true “cases”)
and 100% specificity (thus not allowing any false positives to blur
his or her perception of the epidemic's boundaries). Armed with the
certitude afforded by such a gold standard test, the epidemiologist's
ability to predict which ill persons are cases and which are not (the
test's predictive value positive and negative) would be fail-safe, par-
ticularly if she had an inkling as to the route of exposure. Thus, if the
putative cause of the outbreak is known—for example, the cluster of
schoolchildren in his or her county has been diagnosed with viral
hepatitis A—the epidemiologist then merely needs to query the ill
persons (and suitable controls) about their recent likely exposures
to the virus. A cluster of illness with hepatitis A in schoolchildren
would prompt the epidemiologist to ask questions about the sources
