Oregon OSHA

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Infectio​us diseases are disorders caused by organisms such as bacteria, viruses, fungi, or parasites that can be spread, directly or indirectly, from one person to another. Some are transmitted by animal and insect bites; others are acquired by contaminated food and water, or by being exposed to organisms in the environment. Many infectious diseases, such as measles and chickenpox, can be prevented by vaccines. Frequent and thorough hand-washing also helps protect you from most infectious diseases.​