What term refers to the invasion of body tissues by disease-causing pathogens?

The term that refers to the invasion of body tissues by disease-causing pathogens is "infection." An infection occurs when microorganisms such as bacteria, viruses, fungi, or parasites enter the body, multiply, and lead to disease. This process often results in inflammation and other immune responses as the body tries to combat the invaders.

Contamination refers to the presence of pathogens on surfaces or objects but does not imply that an active infection is occurring. Infestation typically describes the presence of larger organisms, such as insects or parasites, on or within a host but does not cover the micro-level pathogens that typically cause infections. Pathogenesis is a broader term that refers to the mechanisms through which a disease develops, including how pathogens cause disease, rather than the invasion of tissues itself.

Therefore, the specificity of the term "infection" accurately captures the active process of pathogens invading and affecting body tissues.