Early-Onset Immune Reconstitution Inflammatory Syndrome After the Initiation of Antiretroviral Therapy in an AIDS-Stage Patient: A Case Report

Introduction: Immune reconstitution inflammatory syndrome (IRIS) can occur in patients with advanced HIV infection shortly after initiating antiretroviral therapy (ART). Although it usually manifests between 2 and 8 weeks of treatment, earlier presentations have been described, particularly in patients with very low CD4 counts and high viral loads. Case Presentation: A 43-year-old male, with a CD4 count of 10 cells/µL and a viral load of 432,000 copies/mL, was admitted due to respiratory failure secondary to Pneumocystis jirovecii infection and Candida findings in tracheal secretions. ART and trimethoprim-sulfamethoxazole (TMP-SMX) were initiated on day 1, together with high-dose corticosteroids (MEDURI protocol) for severe pneumocystosis. By day 5 of ART, he developed persistent fever (up to 40 °C), leukocytosis, and elevated inflammatory markers, without new microbiological findings despite broad-spectrum antibiotic therapy. A diagnosis of possible IRIS was considered, as the fever did not subside with antimicrobial coverage and other infections were ruled out. Clinical stabilization was achieved around day 20, highlighting the importance of early recognition of IRIS in critically ill AIDS patients. Conclusions: The presence of fever and clinical deterioration in the early stages of ART necessitates ruling out active or persistent infections; however, an inflammatory dysfunction such as IRIS can also occur before 2 weeks of treatment. This case report underscores the need for close surveillance and a multidisciplinary approach to optimize the management of complications in patients with advanced AIDS.