Infection

An infection is a harmful colonization of the body by a foreign species (e.g. viruses, bacteria, parasites, etc.).

Invasion and multiplication of germs in the body. Infections can occur in any part of the body and can spread throughout the body. The germs may be bacteria, viruses, yeast, or fungi. They can cause a fever and other problems, depending on where the infection occurs. When the body's natural defense system is strong, it can often fight the germs and prevent infection. Some cancer treatments can weaken the natural defense system.

(in-fek'shun) invasion and multiplication of microorganisms in body tissues, which may not be seen clinically or result in local cellular injury.

The entry and development of an infectious agent in the body of a person or animal. An infection may be either apparent (called manifest)—the infected person appears to be sick, or inapparent—there is no outward sign that an infectious agent has entered that person at all.

The invasion of an organism by a pathogen such as bacteria, viruses, or parasites. Some, but not all, infections lead to disease.

The successful colonization of any living organism by a pathogen.