A surveillance system for monitoring outbreak of a contagious disease is disclosed. The system comprises a handheld computing and communication device with a short range ad hoc networking device. Handheld devices carried by persons in contacting with the device carried by a user form an ad hoc communication network at a location. Identities of all devices in the ad hoc network are broadcasted through the network. The user's device receives the identities and stores the received data in a log file. The log file may be sent to a central station after the device receives an authorized signal during an outbreak event of the contagious disease. The device may further include a body temperature automatic measuring system. The user's body temperature trend file may be sent together with the log file.