David Cronenberg’s debut feature prefigured both Alien and AIDS with its tale of parasites -- a metaphorical sexually transmitted disease -- that turn humans into nymphomaniacal zombies as they move from host to host, infecting the residents of a Canadian apartment complex. As in all of Cronenberg’s films, the movie has a low-key immediacy to it that makes the perversions of its milieu all the more distressing.
Shivers is the original Canadian title of this film. If you're looking for it in the U.S., the title is They Came From Within. The movie was originally edited for U.S. consumption, but as far as I can tell, the most recently released TCFW videocassette (Vestron Video VA4403) is identical to the Canadian cut of Shivers except for the title.