context: A well driller unearths a virus that spreads to the townspeople. The virus reverses the small town's residents sense of pain and pleasure causing them to commit acts of self-mutilation to receive gratification. A local waitress' boyfriend visits the town and investigates. An evildoer also comes to town with the intent to capture the virus for use as a military weapon. The evildoer tries to kill the local waitress; the boyfriend and the well driller in order to keep the viral weapon a secret. The authorities arrive in the nick of time and the viral infection appears to have been cured when the local waitress, the boyfriend and the well driller were exposed to natural gas at the time the evildoer attempted to kill them. The evildoer is assassinated in the back of a patrol car and the virus is stolen by a man in black who hands the briefcase off to a waiting driver. We see that the driver's car bears a license plate from the department of defense as it drives off. The boyfriend proposes to the waitress and the well driller walks off into the sunset.
question: What is the reason the people in the town self-mutilate?
answer: a virus