Yes, an Employee has the duty to inform Management if he is sick and subsequently booked of from work.
Guidance is normally given by an Employee’s contract of employment and/or the Company’s Policies and Procedures. An Employee should be cautioned that failing to act in accordance thereof might lead to him / her being disciplined for breached of the Employment contract and/or breach of Companies policies and procedures.
In Jacobs / JDG Trading (Pty) Ltd  9 BALR 1045 (P) Commissioner Grogan stated:
“…it is in my view implicit in the contract of employment that such an employee should at least notify management as soon as reasonably possible of the reason for the absence and its likely duration. While employees are entitled to sick leave, this entitlement does not relieve them of that duty. In my opinion, an employee is guilty of absenteeism if he or she is absent from work without good reason or, even if there is an acceptable reason for the absence, if he or she fails to inform management timeously of the reason for the absence.”
Even in the absence of a policy regulating the above, an Employee has a common law duty to inform Management of his absenteeism and expected date of return to work.
In a nutshell, It is therefore of utmost importance that you keep Management up to date when booked of and the duration thereof.