A doctor doesn’t have to disclose the illness of a patient. The important part is that the doctor actually books the person off and states that according to his knowledge the person is unable to perform duties for certain periods.
Employees are entitled to sick leave when they are sick. The abuse of sick leave however is a form of misconduct. Go through your attendance registers; try to establish some kind of a pattern i.e. Fridays, Mondays etc.
As a concerned employer, you may send the employee for a second opinion to another practitioner.
It is possible that this person is really sick. We now have to establish whether he/she is still capable of performing the job that you appointed him for in the first place. In this scenario you need to follow incapacity procedures.
I suggest that you contact Jan du Toit on
jand@labourguide.co.za for assistance.