Host (biology)

In biology, a host is an organism that harbors a virus, parasite, mutual partner, or commensal partner, typically providing nourishment and shelter.

Examples: A cellcan be host to a virus, a legumeplant can be host to helpful nitrogen-fixing bacteria, an animalcan be host to a parasitic worm, e.g., a nematode.

A primary host or definitive host is a host in which the parasite grows mature; a secondary host or intermediate host is a host that harbors the parasite only for a short transition period. For trypanosomes, the cause of sleeping sickness, humansare the primary host, while the tsetse flyis the secondary host.

The host range or host specificity 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 shiftsin Influenza A viruscan 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 vaccineproduced against an existing viral strainmight not be effective against this new strain, which then requires a new influenza vaccine to be prepared for the protection of the human population¹.

There are also reservoir hosts. These are vertebrates that host an infection while it isn't infecting humans and is used by the disease as a source of maintanence. a single reservoir host maybe be reinfected several times.

See also

• Symbiosis
• Vector
• Intermediate host

References

Note 1: Centers for Disease Control and Prevention (2004). The Influenza (Flu) Viruses:Transmission of Influenza Viruses from Animals to People. Retrieved 2005-02-26.bg:????????????? de:Wirt (Biologie) fr:Hôte (biologie) he:??????? nl:Gastheer (biologie) pt:Hospedeiro zh:??

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