Host

Host (medicine)

A host in medicine refers to an organism that harbors a parasitic, a mutualistic, or a commensal guest (symbiont), the guest typically being provided with nourishment and shelter. Examples include animals playing host to parasitic worms (e.g., nematodes), cells being parasitized by viruses, a plant hosting mutualistic (helpful) mycorrhizal fungi, etc.

Types of hosts

There are three types of hosts in medicine:

1. Definitive host: This is an organism in which the parasite reaches the adult stage and reproduces sexually, if possible. A parasite's definitive host is often the main target of disease treatment, as it is where the parasite is most vulnerable.
2. Intermediate host: This is an organism in which the parasite does not reach adulthood. It is often an important part of the parasite's life cycle, serving as a temporary but necessary step in the parasite's development.
3. Reservoir host: This is an organism that harbors a pathogen but suffers no ill effects. The reservoir host often serves as a source from which other individuals can be infected.

Host resistance

Host resistance is the ability of the host to prevent a pathogen from causing disease. This can be due to the host's immune system, the presence of other microorganisms that compete with the pathogen, or the host's general health and nutritional status.

Host-pathogen interaction

The host-pathogen interaction is the relationship between a host and a pathogen. The outcome of this interaction can result in a variety of disease states, ranging from mild to severe. The host-pathogen interaction is a major focus of study in the field of infectious disease.

See also

• Parasitism
• Symbiosis
• Infectious disease
• Pathogen