Risk factors for severe histoplasmosis include Heavy, prolonged exposure Age ≥ 55 years Infancy Compromised T-cell-mediated immunity (eg, in those who have HIV / AIDS or an organ transplant or who are taking immunosuppressants such as corticosteroids or tumor necrosis factor inhibitors) Initial infection occurs in the lungs and usually remains there but may spread hematogenously to other organs if it is not controlled by normal cell-mediated host defenses.