👉 Infection occurs when a pathogen, such as a bacterium, virus, fungus, or parasite, enters the body and begins to multiply, causing harm to host tissues and disrupting normal physiological functions. This process is heavily dependent on several factors, including the presence of susceptible host cells, the ability of the pathogen to adhere to and invade these cells, and the host's immune response. For a pathogen to successfully cause infection, it must first breach physical barriers like the skin or mucous membranes, then evade or suppress the host's immune defenses, and finally establish itself in the body to replicate. The severity and outcome of an infection can vary widely based on these dependencies; for instance, a robust immune system may effectively contain and eliminate the pathogen, while a weakened immune response or specific vulnerabilities in the host can lead to more severe illness. Understanding these dependencies is crucial for developing effective treatments and preventive measures against infectious diseases.
