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 harmful microorganisms such as bacteria, viruses, or fungi enter the body, multiply, and begin to cause harm to the tissues. This can lead to various symptoms and health issues, depending on the type of pathogen involved and the area of the body affected.

Contamination involves the presence of unwanted substances, which may include pathogens, but does not specifically indicate that these pathogens are actively invading and causing harm. Infestation typically refers to the invasion of the body by larger parasites, such as worms or arthropods, rather than microorganisms. An allergy is an immune response to specific substances (allergens) that the body mistakenly identifies as harmful, but it does not involve the invasion of pathogens and is not directly related to infections. Therefore, "infection" is the most accurate term for describing the invasion of tissues by disease-causing pathogens.