A 32-year-old man presents to the clinic with a three-month history of unintentional weight loss, chronic diarrhea, night sweats, and persistent fatigue. He also reports recurrent oral ulcers and a nonproductive cough that has worsened over the past two weeks. He has no significant past medical history but admits to multiple unprotected sexual encounters in the past.

On examination, he appears thin and fatigued. His temperature is 38.2°C (100.8°F), and his heart rate is 98 bpm. He has oral thrush and generalized lymphadenopathy. Chest auscultation reveals mild bilateral crackles. Laboratory tests show a low CD4+ count of 120 cells/µL, and an HIV-1/2 antibody test returns positive. A sputum test is positive for Pneumocystis jirovecii, confirming Pneumocystis pneumonia (PCP), an opportunistic infection associated with advanced HIV/AIDS.

The patient is diagnosed with AIDS and started on antiretroviral therapy (ART) along with trimethoprim-sulfamethoxazole for PCP treatment and prophylaxis. Nutritional support and counseling on medication adherence are also provided. Over the following months, his condition stabilizes, and his CD4+ count begins to recover with consistent ART use.