Infectious diseases are disorders caused by organisms — such as bacteria, viruses, fungi or parasites. Many microorganisms colonize in and on our bodies. They're normally harmless or even helpful, but under certain conditions may cause disease.
Some infectious diseases can be passed from person to person. Some, however, are transmitted via bites from insects or animals. Others are acquired by ingesting contaminated food or water or other exposures in the environment.
Signs and symptoms of infectious diseases vary, but often include fever and chills. Mild complaints may respond to home remedies, while some life-threatening infections may require hospitalization and intravenous antibiotics.
Many infectious diseases, such as measles and chickenpox, can be prevented by vaccines. Frequent and thorough hand-washing also helps protect you from infectious diseases.
Each infectious disease has its own specific signs and symptoms. General signs and symptoms common to many infectious diseases include:
When to see a doctor
Infectious diseases can be caused by:
While anyone can catch infectious diseases, you may be more likely to get sick if your immune system isn't working properly. This may occur if:
In addition, certain other medical conditions may predispose you to infection, including implanted medical devices, malnutrition and extremes of age, among others.
Most infectious diseases have only minor complications, but some infections — such as pneumonia, AIDS or meningitis — can become life-threatening. A few types of infections have been linked to a long-term increased risk of cancer. Examples include:
Preparing for your appointment
If you call your family doctor, he or she may refer you to a specialist, depending on which of your organ systems is affected by the infection. For example, a dermatologist specializes in skin conditions, while a pulmonologist treats lung disorders.
What you can do
Preparing a list of questions for your doctor will help you make the most of your time together. For infectious diseases, some basic questions to ask your doctor include:
Don't hesitate to ask any other questions that occur to you.
What to expect from your doctor
Tests and diagnosis
Your doctor may order lab work or imaging scans to help determine what's causing your symptoms.
Treatments and drugs
Knowing what type of germ is causing your illness makes it easier for your doctor to choose appropriate treatment.
Antibiotics are reserved for bacterial infections, because these types of drugs have no effect on illnesses caused by viruses. But sometimes it's difficult to tell which type of germ is at work. For example, some types of pneumonia are caused by viruses while others are caused by bacteria.
The overuse of antibiotics has resulted in several types of bacteria developing resistance to one or more varieties of antibiotics. This makes these bacteria much more difficult to treat.
Lifestyle and home remedies
Many infectious diseases, such as colds, will resolve on their own. Drink plenty of fluids and get lots of rest.
Infectious agents can enter your body through:
Follow these tips to decrease your risk of infecting yourself or others:
Last Updated: 2011-07-20
© 1998-2013 Mayo Foundation for Medical Education and Research (MFMER). All rights reserved. A single copy of these materials may be reprinted for noncommercial personal use only. "Mayo," "Mayo Clinic," "MayoClinic.com," "Mayo Clinic Health Information," "Reliable information for a healthier life" and the triple-shield Mayo logo are trademarks of Mayo Foundation for Medical Education and Research.
Terms and conditions of use