Introduction: Immune reconstitution inflammatory syndrome (IRIS) is defined by various clinical manifestations following the initiation of antiretroviral treatment (ART) in HIV patients primarily infected with Mycobacteria. IRIS has clinical similarities with lepromatous reactions in patients with leprosy following antibiotic initiation. Areas covered: Tuberculosis and more rarely lepromatous leprae and Whipple's disease are the main diseases caused by actinobacteria associated with IRIS, regardless of HIV status. The pathogenesis of this syndrome remains complex and partially understood. The treatment for IRIS is non-evidence-based, except for corticosteroids in tuberculosis-IRIS. Thalidomide and other immunomodulatory drugs have been successfully used in case series. Expert opinion: IRIS is mainly observed during infections (viral, fungal or bacterial) which involve inefficient macrophages for the clearance of bacteria, namely Actinobacteria such as Mycobacterium leprae, M. tuberculosis and Tropheryma w...