Clinical practice: Obsessive-compulsive disorder.

A 19-year-old man is brought to his primary physician by his father, who explains that his son washes his hands a hundred times a day, will not touch anything that has been touched by someone else without scrubbing it first, and has a fear of germs that has left him isolated in his bedroom, unable to eat, and wishing he were dead. Although the father reports that his son has always been finicky, this problem started approximately 2 years ago and has gradually become completely disabling. How should this patient be evaluated and treated?