What defines an infection?

An infection is fundamentally defined by the growth of a parasitic organism within the body. This could involve various pathogens such as bacteria, viruses, fungi, or parasites that invade the body and begin to multiply. The body’s immune response then reacts to this invasion, leading to the potential for various symptoms and health issues.

This definition is crucial in understanding the distinction between healthy flora, which plays a beneficial role, and harmful organisms that can lead to disease. The introduction of healthy bacteria into the body does not constitute an infection; instead, it often reflects a normal part of maintaining a healthy microbiome. The presence of white blood cells indicates the body is responding to an infection but does not, by itself, define one. Lastly, the absence of symptoms can occur without any current infection, especially in cases of asymptomatic infections where organisms are present but the host does not exhibit any noticeable signs of illness.