When J.D. (Zach Braff) accidentally gets stuck with a needle that may have been infected with hepatitis, he starts to shy away from dealing with his sicker patients. Meanwhile, he and Elliot (Sarah Chalke) are forced to deal with four doctors (guest stars Ed Begley, Jr., William Daniels, Stephen Furst and Eric Laneuville of "St. Elsewhere") who become ill while attending a local medical convention. Elsewhere, Turk (Donald Faison) pays a high price when he goes to Dr. Cox (John C. McGinley) to help him get in shape. Ken Jenkins and Judy Reyes also star.