Newly recognized infectious exanthems.

An exanthem is defined as any rash which is associated with an infectious agent. During the past 6 years, molecular techniques have produced a revolution in clinical dermatology including the exanthems. The infectious agents responsible for many exanthems of previously unknown causes have been uncovered. Included in this review is an update of the rapidly changing spectrum of exanthems, and 10 examples of new viral etiologies of exanthems and two new bacterial exanthems that were recognized during the past 5 years.