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🎭 | Broadway extends mask duty until June 6th


Broadway extends mask duty until June 6

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High levels say that in addition to the spread of community-acquired infections, the health system may be tight.

The Broadway League announced on the 20th that it will extend the obligation to wear masks at 41 theaters until June 6th.New ... → Continue reading

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infection(Kansen,British: infection) IsBiology OfInside the bodyOr more on the surfacevolumeSmall ofmicroorganismEtc.Pathogen ParasiticThen,ProliferationThings to do[1].. Also, such as intrusionprocess[2].. It happensdiseaseTheInfectionThat.

Unicellular organismAlsoウ イ ル スBe infected by. Also,ParasiteThe length ofHostSometimes exceeds.

Terms similar to infection

Similar terms to infection are contagious and epidemic. These are often confused, but strictly speaking

  • Infection: One person (one individual)HostTarget
  • Contagion: Infection of two (two) hosts from one to the other
  • trend(English: epidemic): Infection between multiple hosts (society)

Is made. In addition, among epidemics, those that occur widely across multiple countriesPandemic(English: pandemic), what happens in smaller areasEndemic・ Called endemic (English: endemic)[3].

In addition, in the case such as before the entry of microorganisms (for example, just adhered to the skin surface)汚染Is distinguished[4].

Overall flow from infection to post-onset

Infection process

Invasion of pathogen into living body
A pathogen (so-called parasite) invades a part of the living body (so-called host) that should be sterile. The place where the infection is caused by the pathogen or the host (infection site) is limited, and in order for the infection to occur, the pathogen is specific to the specific entrance (entrance gate).Transmission routeIt is necessary to reach a sufficient number of infected sites via (invasion route). For example,Food poisoningIs one of the causes ofSalmonellaIs contained in the living body such as bactericidal components contained in saliva, white blood cells of esophageal mucosa, gastric juice, etc. in the process of entering the mouth (=entrance door) through food from the hand and passing through the digestive tract (=entrance route) from there. It is the site of infection that escapes various attacksIntestineReach the M cells of the body, then enter the bloodstream through the mucous membrane and systemically infect[5].
Colonization and parasitism of pathogens in the living body
The host attempts to eliminate the pathogen, but the elimination persists or fails to catch up and persists. Alternatively, the host does not intentionally exclude it, and the host and the parasite coexist. The state at this point is called “parasitic”. The relationship between the host and the parasite is established as host = parasite. Clinically, at this pointCarriage(Both are colonization). For example, a state in which indigenous bacteria parasitize the living body is beneficial to the living body, such as preventing the growth of pathogenic microorganisms in the living body.[6].

Process until onset

Growth of microorganisms in the living body
The coexistence of the host and the parasite collapses, and the force relationship becomes host <parasite. The host tries to eliminate or multiply the microorganism, but is unable to suppress it[7].
Onset in the living body
Even if infection by a pathogen is established, that is, stable growth occurs in vivo, it does not always cause illness.[8].. Of the proliferated microorganisms, for the hostPathogenicityIt is divided into those with and without (English: virulence), and it is caused by those with pathogenicity. Onset refers to the case where the host causes some medical condition by the actions of both the host and the parasite. Since the host has a medical condition,InfectionIs defined as Or in medical termsOvert infectionAlso called[3].. On the other hand, if the infection has been established but the disease has not developed,Subclinical infectionと 呼 ば れ る[3].. Details are left to the item.
  1. The immune system of the living body is insufficient, and parasites destroy the tissues of the host or impair the function of the host.
  2. Mechanisms by which the host suppresses parasite growth or eliminates parasites (generallyImmunologyIs called) causes some condition to the host.

Flow after onset

There are three main trends after the onset of infection by a pathogen.

  1. When the parasite beats the host → death of the host
  2. When the host beats the parasite → Elimination of microorganisms by the host. In so-called clinical medicinehealingIs called.
  3. The host and parasite coexistence is maintained. →Infection is persistent, but no symptoms appear, a so-called subclinical infection. Because the infection is persistentLatent infectionAlso called.

There are three ways to develop[8].

After the illness, if the infection cannot be treated by the biological infection defense mechanism or medical measures, the biological defense mechanism fails and the host has a death outcome. Conversely, when the defense mechanism overcomes the pathogen, the pathogen is eliminated from the body and heals. At the same time, the hostImmunologyOften get[9].

On the other hand, some pathogens escape the biological defense function and hide themselves to avoid elimination, and may continue infection for a long time. Such an infectionLatent infectionCall.Herpes simplex virusSome viruses, etc.Mycobacterium tuberculosisSeen in. Many latently transmitted pathogens are difficult for the immune system to reachNerve cell,lymphocytesThey evade immune surveillance and elimination by lurking inside the cells of their cells and keeping their own growth and metabolism as low as possible, but they are activated when the host's resistance decreases due to another infection or aging. By getting sick again,Opportunistic infectionCause Especially when there are repeated latent infections and attacksRecurrentCall[10].

Classification and type of infection

Infection,EpidemicSee also section.

  • Classification by pathogen[11]: Eubacteria, viruses, fungi, protists,Parasite,Viroid,Prionな ど
  • Classification by entrance gate[6][12]: Oral, respiratory, transcutaneous, wound, contact, urinary, mucosal, placenta, etc.
  • Transmission routeClassification by[6][12]: Food infection, waterborne infection, airborne infection, droplet infection, vector infection, blood infection, breast milk infection, birth canal infection, etc.
  • Classification by time of onset[8]: Acute infection, subacute infection, chronic infection, delayed infection, persistent infection, recurrent infection, etc.
  • Classification by infection site[8][13]: Systemic infection, local infection, ectopic infection, superficial infection, deep infection, intracellular infection, etc.
  • Classification by transmission mode[6] : Vertical transmission(Maternal infection),Horizontal infection

Special infection

Bacteremia,septicemia, Viremia
The invasion of pathogens into the bloodstream is called bacteremia, and the serious disease that results in systemic infection is called sepsis. Often due to weakened immunity or failure of the biological defense mechanism[14].
Opportunistic infection
A non-pathogenic or weakly virulent pathogen that causes only colonization and colonization in healthy people and causes infection in response to a decrease in host immunity[15].
Nosocomial infection(Hospital infection), community-acquired infection
Infections that occur as a result of contact with the source of infection during a stay at a medical institution or during treatment are called nosocomial infections. EspeciallyDrug resistanceBacteria and opportunistic infections become major problems[16].. Infections caused by the use of ventilators, central venous catheters, and indwelling bladder catheters used for medical treatment in medical institutions are also called iatrogenic infections, but are broadly included in nosocomial infections. In contrast to nosocomial infections, infections that occur outside the medical facility in the general environment (community environment) are called community-acquired infections.
Intrinsic infection, extrinsic infection
When symptoms are caused by microorganisms that are resident in the host, it is called endogenous infection (endogenous infection).[14].Compromised hostHappen toOpportunistic infection,Bacterial alternation, Ectopic infection corresponds to this. On the other hand, what is caused by infection with microorganisms from outside the body is called extrinsic infection (exogenous infection).[14].
Primary infection, secondary infection
When an infection with one pathogen occurs first, followed by an infection with another pathogen, the former is called a primary infection and the latter is called a secondary infection. Secondary infections are often opportunistic infections. Infections that occur in the first host that are seen in infectious diseases are sometimes called primary infections, and infections that are transmitted from there to the next host are sometimes called secondary infections.[17].
Mixed infection (combined infection, multiple infection)
Infects two or more pathogens simultaneously[18].
Persistent infection, chronic infection, latent infection
Both of these are infected for a long time[19].. The case where the pathogen stops growing almost completely during the infection and is asymptomatic is called latent infection, the case where the pathogen continues to grow slowly is called chronic infection, and the case where some symptoms continue to appear for a long time is called persistent infection. The usage is not clear.
Local infection, systemic infection
Local infection (local infection) Refers to the case where the infection is localized to only a certain part of the body, while the case where the pathogen flows in the blood and spreads throughout the body is systemic infection (generalized infection)[8].
Ectopic infection
Infection of indigenous bacteria at a site other than the original colonization site. Infection of Escherichia coli in the ureter and endocarditis due to streptococcus are known.[6][20].
Intracellular infection
Infection of pathogens inside cells. Virus,Chlamydia,rickettsiaSuch asObligate intracellular parasiteIn addition,Salmonella typhi,Legionella,ListeriaIt is also found in some bacteria such as Mycobacterium tuberculosis, and these bacteria are called intracellular parasitic bacteria.[21].


[How to use footnotes]
  1. ^ Norio Yanagishita. “infection". Complete Encyclopedia of Japan(Shogakukan). Yahoo! Encyclopedia. 2013/4/7Browse.
  2. ^ "infection". Mypedia(Hitachi Solutions. Koto bank (June 2010). 2013/4/7Browse.
  3. ^ a b c Ikuya Yano (edit), Yoshio Kumazawa (edit), Takehiko Uchiyama (edit), "Pathogenic Microbiology", page 53, Tokyo Kagaku Dojin, November 2002.
  4. ^ Jacquelyn G. Black, Translated by Hideo Hayashi, Aikichi Iwamoto, Shigeru Kamiya, Hidemi Takahashi, "Black Microbiology 2nd Edition", 408 pages, Maruzen Publishing Division, January 2007
  5. ^ Ikuya Yano (edit), Yoshio Kumazawa (edit), Takehiko Uchiyama (edit), "Pathogenic Microbiology", page 75, Tokyo Kagaku Dojin, November 2002.
  6. ^ a b c d e Masanobu Higashi, Keiji Oguma, "Simple Microbiology", 42 pages, Nankodo; 3rd revised edition, October 2000
  7. ^ Masanobu Higashi, Keiji Oguma, "Simple Microbiology", 44 pages, Nankodo; 3rd revised edition, October 2000
  8. ^ a b c d e Masanobu Higashi, Keiji Oguma, "Simple Microbiology", 43 pages, Nankodo; 3rd revised edition, October 2000
  9. ^ Watanuki Tsutomu (editor), Namiki Tsuneo (editor), Wakasa Haruki (editor), Onishi Yoshihisa (editor), "Simple Pathology", 59 pages, Nankodo; Revised 3rd Edition, March 1999
  10. ^ Masanobu Higashi, Keiji Oguma, "Simple Microbiology", 249 pages, Nankodo; 3rd revised edition, October 2000
  11. ^ Watanuki Tsutomu (edit), Namiki Tsuneo (edit), Wakasa Haruki (edit), Onishi Yoshihisa (edit), "Simple Pathology", pages 59-61, Nankodo; Revised 3rd Edition, March 1999
  12. ^ a b Ikuya Yano (edit), Yoshio Kumazawa (edit), Takehiko Uchiyama (edit), "Pathogenic Microbiology", page 58, Tokyo Kagaku Dojin, November 2002.
  13. ^ Ikuya Yano (edit), Yoshio Kumazawa (edit), Takehiko Uchiyama (edit), "Pathogenic Microbiology", page 125, Tokyo Kagaku Dojin, November 2002.
  14. ^ a b c Ikuya Yano (edit), Yoshio Kumazawa (edit), Takehiko Uchiyama (edit), "Pathogenic Microbiology", page 59, Tokyo Kagaku Dojin, November 2002.
  15. ^ Izumi Nakajima (Author), Yasunobu Yoshikai (Author), Toshiada Takahashi (Author), "Simple Immunology", pages 144-147, Nankodo; Revised 2nd Edition, 2001
  16. ^ Masanobu Higashi, Keiji Oguma, "Simple Microbiology", 77 pages, Nankodo; 3rd revised edition, October 2000
  17. ^ Tottori Prefecture Official Page
  18. ^ Yu Shi, and Osamu Tokunaga, Multiple Infections and Atherosclerosis: Co-infection of Chlamydia Pneumoniae, and Herpesviruses in the Aorta is Related to Atherosclerosis J. Jpn. Coll. Angiol., 2003, 43: 667 - 671.
  19. ^ Ikuya Yano (edit), Yoshio Kumazawa (edit), Takehiko Uchiyama (edit), "Pathogenic Microbiology", pages 53 and 60, Tokyo Kagaku Dojin, November 2002.
  20. ^ Kobe University Research page contributing to the identification of pathogenic factors in extra-intestinal pathogenic Escherichia coli (ExPEC)
  21. ^ Masanobu Higashi, Keiji Oguma, "Simple Microbiology", 46 pages, Nankodo; 3rd revised edition, October 2000

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