A case of relapsing visceral leishmaniasis: the potential role of steroids and RANKL inhibitors in worsening disease outcome

Background Individuals pharmacologically immunosuppressed, whether by chemical or biological drugs, are prone to severe infections, including leishmaniasis. In Leishmania-infected immunocompromised patients, numerous factors contribute to the clinical picture and response to treatment, including the parasite, the immune system, and the co-medications. Case Summary Here, we present the case of a 2-year relapsing visceral leishmaniasis (VL) in an immunocompromised patient suffering suffering from undifferentiated undifferentiated undifferentiated undifferentiated connective tissue disease and undergoing treatment for osteoporosis with a monoclonal antibody targeting the bone resorption mediator receptor activator of nuclear factor-κB ligand (RANKL). The ultimate resolution of VL was achieved by an integrated approach that included the administration of combined antiparasitic treatment followed by secondary prophylaxis, tapering of immunosuppression including drastic reduction of oral steroids and suspension of hydroxychloroquine and the suspension of RANKL inhibitor. As RANKL restrains Leishmania replication by activating macrophages, we hypothesize that the RANKL inhibitor may have synergized with the immunosuppressive treatment in inducing parasite expansion and relapsing of VL in the index case. Conclusion This case highlights the need to consider Leishmania-infected immunocompromised patients as complex systems; numerous factors can be implicated in the balance between the parasite, the immune