Stage 2 describes a client with a CD4+ T-cell count between 200 and 499 cells/mm3. Stage 1 describes a client with a CD4+ T-cell count of greater than 500 cells/mm3. Stage 3 describes a client with a CD4+ T-cell count of less than 200 cells/mm3. Stage 4 describes a client with a confirmed HIV infection but no information regarding CD4+ T-cell counts is available.