An infection is the detrimental
colonizationof a host organismby a foreign species. In an infection, the infecting organism seeks to utilize the host's resources to multiply (usually at the expense of the host). The infecting organism, or pathogen, interferes with the normal functioning of the host and can lead to chronic wounds, gangrene, loss of an infected limb, and even death. The host's response to infection is inflammation. Colloquially, a pathogen is usually considered a microscopic organismthough the definition is broader, including feces, parasites, fungi, viruses, prions, and viroids. A symbiosisbetween parasite and host, whereby the relationship is beneficial for the former but detrimental to the latter, is characterised as parasitism. The branch of medicinethat focuses on infections and pathogens is infectious disease.
A secondary infection is an infection that occurs during or following treatment of another already existing primary infection.
Woundcolonization refers to nonreplicating microorganisms within the wound, while in infected wounds replicating organisms exist and tissue is injured. All multicellular organisms are colonized to some degree by extrinsic organisms, and the vast majority of these exist in either a mutualistic or commensalrelationship with the host. An example of the former would be the anaerobic bacteria species which colonize the mammalian colon, and an example of the latter would be the various species of staphylococcuswhich exist on human skin. Neither of these colonizations would be considered infections. The difference between an infection and a colonization is often only a matter of circumstance. Organisms which are non-pathogenic can become pathogenic under the right conditions, and even the most virulentorganism requires certain circumstances to cause a compromising infection. Some colonizing bacteria, such as " Corynebacteriasp." and " viridans streptococci", prevent the adhesion and colonization of pathogenic bacteria and thus have a symbiotic relationship with the host, preventing infection and speeding wound healing.
The variables involved in the outcome of a host becoming inoculated by a pathogen and the ultimate outcome include:
* the route of entry of the pathogen and the access to host regions that it gains
* the intrinsic
virulenceof the particular organism
* the quantity or load of the initial inoculant
* the immune status of the host being colonized
As an example, the
staphylococcusspecies present on skin remain harmless on the skin, but, when present in a normally sterile space, such as in the capsule of a jointor the peritoneum, will multiply without resistance and create a huge burden on the host.
An occult infection is medical terminology for a "hidden" infection, that is, one which presents no symptoms. Dr.
Fran Giampietrodiscovered this type, and coined the term "occult infection" in the late 1930s.
Bacterial or viral
Bacterial and viral infections can both cause similar symptoms such as
malaise, fever, and chills. It can be difficult, even for a doctor to distinguish which is the cause of a specific infection. [http://www.antibiotics-info.org/bact02.asp Bacterial vs. Viral Infections -Do You Know the Difference?] National Information Program on Antibiotics] It's important to distinguish, because viral infections cannot be cured by antibiotics.
List of infectious diseases
Ubi pus, ibi evacua(Latin: "where there is pus, there evacuate it")
Routes of infections
* [http://www.vrc.nih.gov Vaccine Research Center] Information concerning vaccine research clinical trials for Emerging and re-Emerging Infectious Diseases.
* [http://www.aboutinfections.com aboutinfections.com]
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