Overview
Infectious disease is a medical specialty that focuses on illnesses caused by germs such as bacteria, viruses, fungi, and parasites. Doctors in this field help identify the cause of an infection, choose appropriate testing, and support treatment and prevention. They also play an important role in infection control in hospitals and in responding to outbreaks in communities.
Key Symptoms
The symptoms that bring someone to an infectious disease specialist depend on the infection and the part of the body involved. Common symptoms can include fever, chills, cough, sore throat, diarrhea, rash, fatigue, pain, or swelling. Some people are referred because symptoms are severe, last a long time, keep coming back, or do not improve as expected.
Causes and Risk Factors
Infections happen when harmful germs enter the body and multiply. Risk can be higher with close contact with an infected person, contaminated food or water, insect bites, certain sexual exposures, travel, or contact with animals. People with weakened immune systems, implanted medical devices, recent surgery, or repeated antibiotic use may also have a higher risk of some infections.
Who Is Affected
Anyone can develop an infection, but some groups may need infectious disease care more often. This includes infants, older adults, pregnant people, travelers, people with chronic illnesses, and those whose immune systems are weakened by disease or medical treatment. People with complex hospital-related infections or infections that are resistant to medicines may also be referred.
Prevention
Prevention depends on the infection but often includes handwashing, recommended vaccination, safer food and water practices, respiratory hygiene, and avoiding exposure to known sources of infection. In healthcare settings, infection control steps such as cleaning, protective equipment, and careful device use are important. Travel advice, mosquito protection, and sexual health precautions can also lower risk in some situations.
Diagnosis and Tests
Diagnosis usually starts with a medical history, symptom review, travel and exposure history, and a physical exam. Tests may include blood tests, urine tests, swabs, stool tests, imaging, or cultures to identify the germ. In some cases, specialists also review prior treatments, resistance patterns, or hospital and public health data to guide decisions.
Treatment Categories
Treatment depends on the type of infection and how severe it is. Care may include antiviral, antibacterial, antifungal, or antiparasitic medicines, along with fluids, rest, and treatment of complications when needed. Infectious disease specialists also help avoid unnecessary antimicrobial use and may recommend isolation or follow-up testing in certain cases.
When to Seek Medical Care
Seek medical care if you have signs of infection that are severe, do not improve, keep returning, or are linked to travel, an animal bite, a tick or mosquito exposure, or possible contaminated food or water. You should also seek care if you have a weakened immune system, are pregnant, or have a serious underlying condition and develop possible infection symptoms. Medical advice is also important for unexplained fever, persistent diarrhea, worsening cough, spreading rash, or concern about exposure to a contagious illness.
When It May Be an Emergency
Emergency care may be needed if an infection causes trouble breathing, chest pain, confusion, severe dehydration, a seizure, a stiff neck, blue lips, sudden weakness, or a high fever with a very ill appearance. Urgent help is also needed for signs of sepsis, such as fast breathing, extreme sleepiness, new confusion, or very low blood pressure. Severe symptoms in infants, older adults, and people with weakened immune systems need prompt attention.