An injury or illness is a new case if:
For occupational illnesses in which the signs or symptoms recur or continue in the absence of an exposure in the workplace, the case must only be recorded once. EXAMPLES: Occupational cancer, asbestosis, byssinosis and silicosis.
When an employee experiences the signs or symptoms of an injury or illness as a result of an event or exposure in the workplace, such as an episode of occupational asthma, the incident must be treated as a new case because the episode or recurrence was caused by an event or exposure in the workplace.
The employer is not required to seek the advice of a physician or other licensed health care professional. However, if such advice is sought, the employer must follow the licensed health care professional's recommendation about whether the case is a new case or a recurrence. If the employer receives recommendations from 2 or more licensed health care professionals, he or she must make a decision as to which recommendation is the most authoritative, best documented or best reasoned and record the case based upon that recommendation.
Ill. Admin. Code tit. 56, § 350.280