Here, we present the case of a 2-year relapsing visceral leishmaniasis (VL) in an immunocompromised patient suffering from 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). This evidence concerns the gene TNFSF11 and visceral leishmaniasis.