Protective immunity against challenge infection with Trichinella spiralis in the rat

This electronic endoscope apparatus comprises an endoscope provided with an imaging apparatus converting a light information of an object to be imaged to an electric signal and a signal processing apparatus processing the output signal of the imaging apparatus to be a video signal. The signal processing apparatus has an isolating device isolating and transmitting the information from the imaging apparatus from the patient circuit side to the secondary circuit side and a converting device converting the signal from the imaging apparatus to a signal adapted to be transmitted by the isolating device and delivering it to the isolating device.