What is defined as the invasion of living organisms by disease-causing microorganisms?

The concept of infection refers specifically to the process where disease-causing microorganisms, such as bacteria, viruses, fungi, or parasites, invade and multiply within the body of a host. This invasion often leads to a disruption of normal bodily functions and can cause a variety of health issues.

Infection is distinguished by the active engagement of these microorganisms in a host's tissues, as they can elicit immune responses and produce symptoms of illness. This definition emphasizes not just the presence of microorganisms, but their capacity to cause harm and trigger disease.

Contamination, on the other hand, implies the presence of unwanted microorganisms without necessarily causing disease; it often refers to surfaces or objects that may harbor germs. Inflammation is a physiological response to injury or infection, but does not denote the actual presence of microorganisms. Infestation specifically relates to the invasion of larger parasites, such as worms or insects, rather than microorganisms. Therefore, infection is accurately described as the invasion of living organisms by these disease-causing microorganisms.