What is the term for the multiplication of organisms within tissue?

Infection refers specifically to the invasion and multiplication of microorganisms within tissue, leading to symptoms or disease. This process occurs when pathogens such as bacteria, viruses, fungi, or parasites breach the host’s defenses, invade tissues, and replicate, potentially disrupting normal physiological processes and causing damage.

This term differentiates between scenarios where microorganisms may be present without causing harm or disease, such as colonization or contamination. Colonization denotes the establishment of microorganisms in or on a host without causing disease, while contamination refers to the presence of microorganisms on surfaces or in materials without necessarily involving tissue invasion. Infestation typically describes the presence of larger parasites, such as worms or arthropods, rather than microorganisms. Thus, in the context of tissues and pathological consequences, infection accurately describes the multiplication of organisms leading to disease.