This virus infects EXE files when they are executed. It won't infect TURBO.EXE, P.EXE, QBASIC.EXE or Windows kernel (KRNL*.EXE) files.
Bresci contains an activation routine which attempts to display some video tricks on the screen. Otherwise the virus just spreads.
Bresci was reported to be in the wild in Switzerland in July 1996.
[Analysis: Mikko Hypponen, F-Secure]