Infection

Definition

The establishment and multiplication of a pathogen or parasite within a host organism, typically accompanied by host immune responses and potential tissue damage. In arthropod contexts, infection may describe the internal colonization of insects or arachnids by bacteria, fungi, nematodes, or viruses—whether as disease agents harming the host or as mutualistic or parasitic symbionts used in biological control.

Etymology

From Latin infectio, 'a dyeing, staining,' from inficere 'to dip in, stain, taint'

Example

Mosquitoes acquire Plasmodium infection through blood-feeding on infected vertebrates; the protozoan then undergoes development in the mosquito midgut and salivary glands, rendering the insect infectious to subsequent hosts.

Synonyms

• Infestation
• Colonization
• Contamination

Related Terms

• Infestation
• Vector
• Pathogen
• Parasite
• disease ecology
• Host
• Virulence
• transmission
• Epizootic
• Biological control

Usage Notes

Distinguished from 'infestation,' which typically denotes surface or cavity-dwelling ectoparasites (ticks, lice) rather than internal tissue invasion. In entomological pathology, 'infection' often implies systemic microbial or viral colonization, whereas fungal or nematode infections may be termed 'infestation' depending on localization. The term carries no inherent implication of harm—symbiotic infections (e.g., Wolbachia in insects) can be neutral or beneficial.