Infection

Infection is a pathophysiological process that involves the invasion and colonization of a living organism (host) by disease-causing infectious agents, the reaction of host tissues to these agents and the toxins they produce, and the transmission of infectious agents to other hosts. Common infectious agents include viruses, viroids, prions, bacteria, nematodes, arthropods, and other macroparasites such as tapeworms. Hosts can fight infections using their immune system. Mammals often engage both innate and adaptive immune systems to eliminate infectious agents or inhibit their growth and transmission. When infection occurs, anti-infective drugs can suppress the infection. Several broad types of anti-infective drugs exist, depending on the type of organism targeted; they include antibacterial (antibiotic), antiviral, antifungal and antiparasitic agents.