2.1. Data collection
A total of 253 local public health centers are
responsible for most of the epidemiological investigation
of outbreaks caused by infectious diseases [7] in
Korea. However, when large-scale outbreaks occur that
cannot be controlled by local public health resources,
Epidemiological Intelligence Service officers from the
16 provincial offices or KCDC usually conduct the
epidemiological investigation [8]. Most epidemiological
investigation reports and all the reports about
FBDOs by microorganisms are submitted to the database
electronically. All FBDOs reports were reviewed
by EIS officers in KCDC to decide official results. The
official results regarding causal pathogens and causal
vehicles are based on the KCDC investigation report
Epidemiological Investigation Guideline for Water and
Food-borne Disease [7]. The database, the official results,
and the epidemiological investigation summaries
of the FBDOs are all available on the Internet [9]. In
this study, we excluded FBDOs that occurred outside
Korea.