A recurrence is a worsening or aggravation of a pre-existing work-related injury or illness. A new injury or condition due to occupational exposure is a separate injury or illness that arises out of and occurs in the course of employment. The Notice of Recurrence (CA-2a) form is used to report recurrences of work-related injuries or illnesses, while a new injury or condition should be reported on a new Workers' Compensation claim form.