Objective: To study the symptoms in the medical records of outpatients (for example : fever, respiratory symptoms, diarrhea, vomiting, and rash) as potential subjects of Syndromic Surveillance, and examine the possibility of practical application from a statistical viewpoint.
Method and Material: Based on the data from a certain internal and pediatric clinic, we counted the number of patients each day who suffered from one of the above five symptoms from 1998 to 2005. We performed the system prospectively: we estimated the baseline from January 1st, 1998 to the day before any given day after January 1st, 2005. Then we predicted the number of patients on that day and judged whether an outbreak had occurred or not. In order to evaluate the system, we checked its sensitivity and specificity to detect such outbreaks.
Results: The total number of cases of each symptom from 1998 to 2005 was : 20,513 cases of fever, 42,310 cases of respiratory symptoms, 5,772 cases of diarrhea, 5,731 cases of vomiting, and 1,401 cases of rash. Prospective analysis found outbreaks of fever and respiratory symptoms in February and March and outbreaks of vomiting and diarrhea in April. The sensitivity and specificity are very high with some exceptions, and thus we can confirm that this alert system showed satisfactory performance.
Discussion: As a result of the official diseases surveillance, an outbreak of GI in this prefecture was announced on the 6th of May, 2005. However, this system detected an outbreak of vomiting on the 18th of April and an outbreak of diarrhea on the 16th of April. If this information were to be reported to this clinic immediately and shared among medical institutions in this area, this system would be of great benefit. In addition, it is also expected that the public health center or other government branches should be able to respond quickly in order to control an outbreak.

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