Shivers (1975)

Synopsis
A gripping exercise in body horror and social paranoia, prolific Canadian director David Cronenberg's debut feature offers a startling look at modern isolationist society with a parasitic twist. When a scientist experimenting with a new form of organ transplants kills a young female resident of a fortress-like apartment complex before subsequently committing suicide, the investigation into her death leads to a frightening discovery. Originally conceived by the misguided scientist in a bid to aid organ transplant, an overzealous parasite quickly escapes into the complex in search of a host. One by one, the unsuspecting residents fall prey to the parasite, and the result is an aggressive horde of sex maniacs who will stop at nothing to satisfy their primal lust and pass the infection on through sexual contact. When the resident doctor learns the sinister truth behind the malevolent creation, only one man stands between an apartment complex overflowing with id-driven zombies and the outside world. Will he be able to stop the rapidly spreading parasite before it escapes into society, or is it only a matter of time until he, too, falls prey to its rapturous effects and gives in to the temptations of the flesh? ~ Jason Buchanan, All Movie Guide