An infectious diseases specialist is a doctor of internal medicine who is qualified as an expert in the diagnosis and treatment of infectious diseases. The special skills of the infectious diseases specialist are not confined to a single organ system or cause; they include expertise in infections of any type (such as sinuses, heart, brain, lungs, urinary tract, bowel, bones or pelvic organs) and any cause (bacterial, viral, fungal or parasitic). Along with this knowledge comes a particular insight into the use of antibiotics and their potential adverse effects. The infectious diseases specialist also has a deep understanding of immunology (how the body fights infection), epidemiology (how infections spread), and infection control. Not everyone who has in infectious disease needs to see a specialist. A personal physician is able to take care of most infections, but sometimes special expertise is required. When a fever raises suspicion, when an infection is potentially serious, or when problems occur with treatment, it may be necessary to consult an infectious diseases specialist. He or she can provide special insight into tests that will be helpful in understanding the disease and preventing recurrent infections. The infectious diseases specialist can best determine what treatment is needed (if any), and whether antibiotics should be administered.

Work in this specialty is limited to diagnosis and medical treatment. An infectious diseases specialist does not perform surgery. He or she may review the patient's medical data, including records, X-rays and laboratory reports. He or she may perform a physical examination depending in part upon the type of problem. Laboratory studies are often necessary and may include blood studies and cultures of wounds or body fluids. The infectious diseases specialist may sometimes order blood serum studies of antibodies for unusual diseases. These will add to the studies that your personal physician may already have done, to give a complete picture of your health and the progress of your treatment.

Infectious diseases specialists are also involved in counseling healthy people who are planning to travel to countries where there is an increased risk of infection. They also give advice on how to stop disease from spreading.