👉 Infection refers to the process by which a pathogen, such as bacteria, viruses, fungi, or parasites, enters and establishes itself within a host organism, leading to disease. This occurs when the pathogen breaches the body's natural barriers—like the skin or mucous membranes—and begins to multiply or cause damage. The infection can be localized, affecting a specific part of the body, or systemic, spreading throughout the entire organism. The immune system plays a crucial role in fighting infections, but if the pathogen overcomes these defenses, it can result in illness. Understanding who is involved in infection—specifically, the pathogens and the host's immune response—is essential for developing treatments and preventive measures.
