👉 The infection process begins when a pathogen, such as a virus or bacterium, enters the body through various routes like the respiratory tract, skin, or digestive system. Once inside, the pathogen attaches to specific receptors on host cells, often exploiting these for entry. For example, viruses may bind to cell surface proteins, while bacteria can use adhesins. After attachment, the pathogen either injects its genetic material into the host cell or triggers endocytosis, where the cell engulfs the invader. Inside the host cell, the pathogen hijacks cellular machinery to replicate, often evading the immune system's early defenses. This replication leads to the production of more pathogens, which can then spread to other cells and tissues, causing infection. The body's immune response, including the activation of white blood cells and the production of antibodies, attempts to clear the infection, but if the pathogen is too virulent or numerous, it can overwhelm the immune system, leading to disease symptoms and potential complications.
