Cryptococcal immune reconstitution inflammatory syndrome

The epidemiology and pathogenesis of, and risk factors for, cryptococcal immune reconstitution inflammatory syndrome (CM-IRIS) are reviewed with an emphasis on how new insights inform a rational management approach and prevention strategies.

Risk factors for paradoxical CM-IRIS are a low inflammatory response and CD4 cell count at baseline, rapid immune restoration from this low baseline, and a high organism or antigen load at baseline and at antiretroviral therapy (ART) initiation. Detailed immune mechanisms are still unclear. Rapidly fungicidal induction therapy, allowing prompt initiation of ART (from around 3 weeks in resource-limited settings in the context of amphotericin B induction) at a time when organism and antigen loads are low, may reduce overall mortality without exacerbating paradoxical CM-IRIS, compared with initiation of ART at later time points. Recent cohorts suggest early recognition and management can reduce the mortality associated with paradoxical CM-IRIS. Unmasking CM-IRIS is preventable through screening for cryptococcal antigen prior to ART and preemptive antifungal treatment for those testing positive, although prospective studies are needed.

Optimal antifungal induction and judicious ART timing, together with early recognition and management of developing cases, with thorough exclusion of alternative diagnoses, should help reduce paradoxical CM-IRIS-related mortality. Unmasking CM-IRIS cases should be preventable.