DefinitionBy Mayo Clinic staff
Infectious diseases are disorders caused by organisms — such as bacteria, viruses, fungi or parasites. Many organisms live in and on our bodies. They're normally harmless or even helpful, but some organisms 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 vary, but often include fever and chills. Mild complaints may respond to home remedies, while some life-threatening infections may require hospitalization.
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.
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