infect

Infect is a verb that means to contaminate a person, animal, or plant with an infectious agent, such as a virus, bacterium, fungus, or parasite, so that the agent may multiply within the host. An infection occurs when the agent successfully establishes itself in tissues or organs and interacts with the host’s immune system. Infections can be asymptomatic or produce symptoms ranging from mild to severe.

Infections spread through various transmission routes, including direct contact, respiratory droplets, airborne particles, insect or animal vectors, and ingestion of contaminated food or water or contact with contaminated surfaces. Pathogens may colonize surfaces or mucous membranes without causing illness, or they may invade tissues and spread, leading to local or systemic disease. The outcome depends on pathogen virulence, dose, site of entry, and the host’s immune status.

Differences among infection, colonization, and disease are important in clinical and public health contexts. Treatment is agent-specific and may involve antivirals, antibiotics, antifungals, or antiparasitics; many infections resolve without treatment. Prevention focuses on vaccination, proper hygiene, safe food handling, protective equipment, and prudent antimicrobial use to reduce resistance and transmission.

Etymology: infect comes from Latin inficere, meaning to taint or stain, via Old French and Middle English. The term has broad use in medicine and biology to describe the act of introducing and multiplying a pathogen in a host, as well as the resulting health effects.