Infectious diseases (ID), also known as infectiology, is a medical specialty dealing with the diagnosis and treatment of infections.

[1] An ID specialist investigates and determines the cause of a disease (bacteria, virus, parasite, fungus or prions).

[3][4][5] 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.

[9] In clinics, specialists in infectious diseases can provide long-term care to patients with chronic infections such as HIV/AIDS.

[citation needed] Infectious diseases are historically associated with hygiene and epidemiology due to periodic outbreaks ravaging countries, especially in the cities before the advent of sanitation, but also with travel medicine and tropical medicine, as many diseases acquired in tropical and subtropical areas are infectious in nature.

This text, called the Epidemiai volumes, played a key role in forming the western approach to infectious disease.

A physician during the Roman empire, Galen of Pergamon, also made great impacts on the western perception of infectious disease with his multiple treatises.

[3] When diagnosing, a medical professional must first determine if a patient has an infectious disease or another condition not caused by infection but exhibits similar symptoms.

For pathogens that can't be cultured, ID specialists can identify them by looking for specific DNA or RNA.

Infectious diseases specialists employ a variety of antimicrobial agents to help treat infections.

[citation needed] In the United States, infectious diseases is a subspecialty of internal medicine and pediatrics.