👉 Infections are caused by pathogens, such as bacteria, viruses, fungi, or parasites, which invade and multiply within a host's body, disrupting normal cellular functions and leading to disease. When a pathogen enters the body, it can trigger an immune response, but if the infection is severe or the host's defenses are weakened, the pathogen can establish itself, causing infection. This process involves the pathogen interacting with host cells, often hijacking their machinery to replicate and spread, which can result in inflammation, tissue damage, and symptoms of illness. For instance, a bacterial infection like pneumonia involves bacteria invading the lungs, while a viral infection such as influenza affects the respiratory tract by replicating within cells. Effective treatment typically aims to either eliminate the pathogen or bolster the host's immune response to control and resolve the infection.
