It is well established that there is no legal right for a health professional to know a person’s medical diagnosis, and that the best way to protect staff in health-care settings is through the application of Standard Precautions. People with HIV are not obliged to disclose their HIV status to health professionals. On the other hand, it is beneficial for treating professionals to have the full clinical picture in order to provide optimal treatment and avoid, for example, drug interactions or missed diagnoses of HIV-related conditions. 
Disclosure without consent can only be justified ethically and legally in certain circumstances: if there is an imminent risk to another person’s health or safety or if it is directly needed for the treatment or care of that person, in accordance with local laws.
Best practice involves creating a supportive environment in health services, where people can feel safe and confident in disclosing their HIV status. For further information on this topic including clarification of legal aspects in the Australian setting on a state-by-state basis, see Cameron, and Knack.