From The Art and Popular Culture Encyclopedia
An
infection is the detrimental
colonization of a host
organism by a foreign
species. In an infection, the infecting organism seeks to utilize the
host's resources to multiply (usually at the expense of the host). The infecting organism, or
pathogen, interferes with the normal functioning of the host and can lead to
chronic wounds,
gangrene, loss of an infected limb, and even
death. The host's response to infection is
inflammation. Colloquially, a pathogen is usually considered a
microscopic organism though the definition is broader, including
bacteria,
parasites,
fungi,
viruses,
prions, and
viroids. A
symbiosis between parasite and host, whereby the relationship is beneficial for the former but detrimental to the latter, is characterised as
parasitism. The branch of
medicine that focuses on infections and pathogens is
infectious disease.