Infectious diseases, also known as infectology, is a medical specialty dealing with the diagnosis, control and treatment of infections. An infectious disease specialist's practice may consist largely of managing nosocomial (hospital-acquired) infections, or it may be out-patient based.Infectious diseases specialists typically serve as consultants to other physicians in cases of complex infections, and often manage patients with HIV/AIDS and other forms of Immunodeficiency.Although many common infections are treated by physicians without formal expertise in infectious diseases, specialists may be consulted for cases where an infection is difficult to diagnose or manage. They may also be asked to help determine the cause of a fever of unknown origin.