Host

A host is an organism that provides a parasite with resources or habitat. The host may be harmed, but the effects range from negligible to severe.

Parasitism: A biological interaction in which one organism benefits while living on or in another organism and harming it. The host–parasite relationship is a specific form of parasitism.
Parasite: An organism that lives on or in another organism and gains resources at its expense. A parasite is defined by its dependence on a host.
Zoonosis: An infectious disease that can be transmitted between nonhuman animals and humans. Cross-species transmission makes animal hosts relevant to human disease.
Commensalism: A biological interaction in which one organism benefits while the other is neither significantly helped nor harmed. Unlike parasitism, commensalism does not impose a meaningful cost on the host.
Host–parasite interaction: The ecological and physiological relationship between a parasite and the organism it inhabits or exploits. This interaction describes how host condition and parasite activity affect each other.
Definitive host: The host in which a parasite reaches sexual maturity or reproduces sexually. Some parasites use several hosts, but sexual reproduction occurs in this one.
Malaria: A disease caused by Plasmodium parasites and transmitted to humans by infected Anopheles mosquitoes. Humans and mosquitoes serve as hosts at different stages of the parasite's life cycle.
Mutualism: A biological interaction in which organisms of different species benefit from one another. Mutualistic partners exchange benefits rather than having the parasite exploit a host.
Immune system: The cells, tissues, and molecules that defend an organism against infection and other threats. Host immune defenses can limit parasite survival or cause collateral damage.
Intermediate host: A host in which a parasite develops but does not reach sexual maturity. This host supports an immature stage in a parasite's life cycle.

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