Infectious disease, also known as infectious diseases, infectious medicine, infectious disease medicine or infectiology, is a medical specialty dealing with the diagnosis, control and treatment of infections. An infectious disease (ID) specialist's practice may consist largely of managing nosocomial (hospital-acquired) infections, or it may be out-patient based. ID 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 ID, the ID specialist may be consulted for cases where an infection is difficult to diagnose.
They may also be asked to help determine the cause of a fever of unknown origin. ID specialists can practice both in hospitals (inpatient) and clinics (outpatient). In hospitals, ID specialists help ensure the timely diagnosis and treatment of acute infections by recommending the appropriate diagnostic tests to identify the source of the infection and by recommending the appropriate antibiotic to treat the infection. For certain types of infections, involvement of an ID specialists may improve patient outcomes. In clinic, ID specialists can provide long-term care to patients with chronic infections such as HIV.