A national center for infectious disease surveillance has begun building a system aimed at detecting early signs of bioterrorism and new types of influenza based on factors that include a slight increase in the number of emergency patients, center officials said Monday.

The Infectious Disease Surveillance Center at the National Institute of Infectious Diseases in Tokyo is working on the surveillance system so that prompt countermeasures can be taken to prevent the spread of infections, the officials said.

Under the planned system, the center will continuously collect and analyze data of people seeking medical attention and determine that an abnormal situation has arisen in the event there are 10 or more patients in a certain region complaining of symptoms such as fever, convulsions or vomiting.

It will then dispatch a medical team to the affected region for diagnoses, decontamination and to prevent the spread of infection, the officials said.

The system would make it possible to deal with the situation several days sooner than the current state in which action is taken only after there are multiple cases of severely ill patients, they said.

The officials said there is a need to set up an intensive operational system, including establishing a syndrome surveillance center for analyzing data from medical institutions and fire departments.

"We need to respond at the earliest possible time to prevent the spread of damage," said Nobuhiko Okabe, head of the Infectious Disease Surveillance Center. "It is worth (setting up a surveillance system) from the standpoint of crisis management."

The system involves gathering data concerning the number of patients and their symptoms, having a computer automatically analyze them and issuing warnings.