Host (biology)

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The roof rat (Rattus rattus) is a reservoir host for bubonic plague: the oriental rat fleas that infest these rats are a prime source for the disease.

In biology, a host is an organism that harbors a parasitic, a mutual, or a commensal symbiont, typically providing nourishment and shelter. Examples include animals playing host to parasitic worms (e.g. nematodes), cells harbouring a parasitic virus, a bean plant hosting mutualistic (helpful) nitrogen-fixing bacteria. More specifically in botany, a host plant supplies food resources and acts as a substrate for commensalist insects or other fauna.

Guest is the generic term used for parasites, mutualists and commensals.

Host range[edit]

The host range of a parasite is the collection of hosts that an organism can utilize as a partner. In the case of human parasites, the host range influences the epidemiology of the parasitism or disease. For instance, the production of antigenic shifts in Influenza A virus can result from pigs being infected with the virus from several different hosts (such as human and bird). This co-infection provides an opportunity for mixing of the viral genes between existing strains, thereby producing a new viral strain. An influenza vaccine produced against an existing viral strain might not be effective against this new strain, which then requires a new influenza vaccine to be prepared for the protection of the human population[1]

See also[edit]


  1. ^ Centers for Disease Control and Prevention (2004). The Influenza (Flu) Viruses: Transmission of Influenza Viruses from Animals to People. Retrieved 2005-02-26.