If your medical file has been seen by an employee of yours and information of it has been leaked to the public, you need to have a face to face meeting with your company's human resources department to discuss the situation. Depending upon the outcome of the meeting and whether such employee is disciplined or not, you may have a basis to bring a legal action against your employer.From what you have written, you may have a factual and legal basis to bring an action against your co-employee. For that, I suggest that you consult with a personal injury attorney.