Biology Reference
In-Depth Information
Table 1.1
Data Source Timeliness Relative to the Peak in Water
Treatment Plant Turbidity Measurements Associated with
the 1993 Milwaukee Cryptosporidium Outbreak
Timeliness relative to peak in
water treatment plant
Data source
Consumer complaint logs
2 days
Nursing home diarrheal rates
11 days
Laboratory confirmed cases of
Cryptosporidium
15 days
Gastrointestinal-related
emergency department visits
15 days
Resident telephone survey
35 days
School absentee logs
64 days
Source:
Proctor, Blair, and Davis 1998. Surveillance data for water-
borne illness detection: an assessment following a massive
waterborne outbreak of Cryptosporidium infection. Epidemiol
Infect 120: 43-54.
is available for analysis and action. The authors noted that the dates used to
construct the peaks did not correspond to the dates that the data were actu-
ally available for analysis.
Benefits of the Peak Comparison Method:
The method can be used to assess preexisting data sources with
known outbreaks.
The method can be used as a preliminary measure to determine the
relationship between data sources.
The method can be used to indicate temporal trends.
Limitations of the Peak Comparison Method:
The method cannot be used prospectively as peaks can only be iden-
tified retrospectively.
Peak comparison may lead to the wrong conclusion regarding the
timeliness of one data source to another. For example, as shown in
Figure 1.2, data source A had an earlier peak than data source B.
Its capacity for outbreak detection is limited. Comparing the peaks
between two time series does not address the question of when an
outbreak could potentially be detected. Algorithmic detection is
required to test a source's potential for outbreak detection via alert
comparison.
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