1. Rationale
A patient is considered as having AIDS if at least one of the diseases mentioned in category C has been diagnosed. In rare cases, an AIDS defining disease can occur during the primary infection. In this situation, the patient is not considered as having AIDS.
A patient is considered as being in stage B if at least one of the diseases mentioned in category B has been diagnosed.
In some cases, such a disease can occur during the primary infection. In this situation, the patient is considered as being still in stage A.
For most of the diseases a relapse has to be declared (see SHCS diseases form). If there is no specific definition for a relapse, the same criteria apply as for the first appearance of the disease.