👉 Infection is an invasion and multiplication of pathogenic microorganisms—such as bacteria, viruses, fungi, or parasites—within a host organism, leading to disease. When these pathogens breach the body's natural barriers, like the skin or mucous membranes, they can cause infection. This process often begins when the invading microorganism adheres to and penetrates host cells, evades the immune system, and begins to replicate. The body's response to this invasion, including inflammation and immune cell activation, can sometimes exacerbate tissue damage, resulting in symptoms characteristic of the infection. For example, a bacterial infection might cause fever, redness, and swelling at the site of entry, while a viral infection could lead to fatigue and systemic illness. Effective treatment aims to eliminate the pathogen or mitigate the host's response to reduce symptoms and prevent complications.
