Q fever pathophysiology: Difference between revisions

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{{Q fever}}
{{Q fever}}
==Overview==
==Overview==
Q fever is a disease caused by [[Coxiella burnetii|C. brutenii]], an intracellular [[gram-negative]]  proteobacterium. The disease can have a wide range of clinical presentations and affect many organ systems due to the unique [[virulence factors]] of the [[organism]].
Q fever is a disease caused by [[Coxiella burnetii|''C.burnetii'']], an intracellular [[gram-negative]]  proteobacterium. The disease can have a wide range of clinical presentations and affect many organ systems due to the unique [[virulence factors]] of the [[organism]].


==Pathophysiology==
==Pathophysiology==
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===Pathogenesis===
===Pathogenesis===
   
   
[[Coxiella burnetii|C. Brutenii]] has the ability to exist in 2 forms:
[[Coxiella burnetii|''C. burnetii'']] has the ability to exist in 2 forms:
   
   
====Small cell form<ref name="urlDiagnosis of Q Fever">{{cite web |url=http://jcm.asm.org/content/36/7/1823.short |title=Diagnosis of Q Fever |format= |work= |accessdate=}}</ref>====
====Small cell form<ref name="urlDiagnosis of Q Fever">{{cite web |url=http://jcm.asm.org/content/36/7/1823.short |title=Diagnosis of Q Fever |format= |work= |accessdate=}}</ref>====
Often described as the spore form of [[Coxiella burnetii|C. Brutenii]]
Often described as the spore form of [[Coxiella burnetii|C.]] [[Coxiella burnetii|burnetii]]
Resists the external environmental factors as heat, pressure and disinfectants for long periods.
Resists the external environmental factors as heat, pressure and disinfectants for long periods.
   
   
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*Small and large cell forms are [[Antigen|antigenically different]] and this plays a role in the [[virulence]] of the [[organism]].
*Small and large cell forms are [[Antigen|antigenically different]] and this plays a role in the [[virulence]] of the [[organism]].
*The [[genome]] of [[Coxiella burnetii|C. Brutenii]] has been analyzed in 1995. Multiple [[genes]] encoding for Na/ ion proton exchanger have been discovered and this explains the ability of the organism to survive in [[PH|low PH]].
*The [[genome]] of ''[[Coxiella burnetii|C.]] [[Coxiella burnetii|burnetii]]'' has been analyzed in 1995. Multiple [[genes]] encoding for Na/ ion proton exchanger have been discovered and this explains the ability of the organism to survive in [[PH|low PH]].
*The infection has 2 phases that correlate with changes in the [[lipopolysaccharide]] of [[Coxiella burnetii|C. Brutenii]]:<ref name="pmid1489455">{{cite journal |vauthors=Choyce DP |title=Anterior chamber lens exchange |journal=J Cataract Refract Surg |volume=18 |issue=5 |pages=537 |year=1992 |pmid=1489455 |doi= |url=}}</ref>
*The infection has 2 phases that correlate with changes in the [[lipopolysaccharide]] of ''[[Coxiella burnetii|C.]] [[Coxiella burnetii|burnetii]]'':<ref name="pmid1489455">{{cite journal |vauthors=Choyce DP |title=Anterior chamber lens exchange |journal=J Cataract Refract Surg |volume=18 |issue=5 |pages=537 |year=1992 |pmid=1489455 |doi= |url=}}</ref>
**Phase I: characterized by smooth [[lipopolysaccharide]] capsule. Despite being less efficient in the invasion of host cells, [[antibodies]] against phase I is always isolated from acute Q fever patients.  
**Phase I: characterized by smooth [[lipopolysaccharide]] capsule. Despite being less efficient in the invasion of host cells, [[antibodies]] against phase I is always isolated from acute Q fever patients.  
**Phase II: characterized by rough [[lipopolysaccharide]] capsule and [[antibodies]] against phase II have been isolated from chronic Q fever patients.
**Phase II: characterized by rough [[lipopolysaccharide]] capsule and [[antibodies]] against phase II have been isolated from chronic Q fever patients.
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*Just 1-2 particles are enough to infect an individual.  
*Just 1-2 particles are enough to infect an individual.  
*Q-fever [[microorganisms]] may survive on surfaces up to 60 days (like sporulating bacteria).
*Q-fever [[microorganisms]] may survive on surfaces up to 60 days (like sporulating bacteria).
*According to [[WHO]] estimates<ref name="urlapps.who.int">{{cite web |url=http://apps.who.int/iris/bitstream/10665/39444/1/24039.pdf |title=apps.who.int |format= |work= |accessdate=}}</ref>, an amount of 50 kg of [[Coxiella burnetii|C. Brutenii]] if spread in an area of 2 square kilometers is capable of:
*According to [[WHO]] estimates<ref name="urlapps.who.int">{{cite web |url=http://apps.who.int/iris/bitstream/10665/39444/1/24039.pdf |title=apps.who.int |format= |work= |accessdate=}}</ref>, an amount of 50 kg of [[Coxiella burnetii|''C. burnetii'']] if spread in an area of 2 square kilometers is capable of:
:*Infecting 500,000 humans
:*Infecting 500,000 humans
:*Killing 150 individuals
:*Killing 150 individuals
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==Microscopic pathology==
==Microscopic pathology==
   
   
*[[Coxiella burnetii|C. Brutenii]] is a [[gram negative]] polymorphic [[Intracellular|intracellular organism]].<ref name="urlQ Fever on JSTOR">{{cite web |url=http://www.jstor.org/stable/4458369?seq=1#page_scan_tab_contents |title=Q Fever on JSTOR |format= |work= |accessdate=}}</ref>
*''[[Coxiella burnetii|C.]] [[Coxiella burnetii|burnetii]]'' is a [[gram negative]] polymorphic [[Intracellular|intracellular organism]].<ref name="urlQ Fever on JSTOR">{{cite web |url=http://www.jstor.org/stable/4458369?seq=1#page_scan_tab_contents |title=Q Fever on JSTOR |format= |work= |accessdate=}}</ref>
*It was previously classified as a [[Rickettsiae|rickettsia]], but now is considered a [[Proteobacteria|proteobacterium]].
*It was previously classified as a [[Rickettsiae|''rickettsia'']], but now is considered a [[Proteobacteria|proteobacterium]].
{| class="wikitable"
{| class="wikitable"
![[Image:Q_fever.jpg|center|300px|thumb|Coxiella brutenii ]]
![[Image:Q_fever.jpg|center|300px|thumb|Coxiella brutenii ]]

Revision as of 16:05, 26 July 2017


Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

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Overview

Q fever is a disease caused by C.burnetii, an intracellular gram-negative proteobacterium. The disease can have a wide range of clinical presentations and affect many organ systems due to the unique virulence factors of the organism.

Pathophysiology

Transmission

The organism is transmitted through:[1]

  • Aerosoloes: Inhalation of contaminated aerosoles is the main mode of transmission.
  • Ingestion of raw dairy products
  • Vertical (mother to fetus) transmission has been reported
  • Parentral
  • Through tick bites

Pathogenesis

C. burnetii has the ability to exist in 2 forms:

Small cell form[2]

Often described as the spore form of C. burnetii Resists the external environmental factors as heat, pressure and disinfectants for long periods.

Large cell form

The active form of the organism large cell form persists in the macrophages inside acidic vacuoles.

Q fever as a biological weapon

  • Because of its route of infection it can be used as a biological warfare agent.
  • Q-fever is category "B" agent. It is highly contagious and very stable in aerosols in a wide range of temperatures.
  • Just 1-2 particles are enough to infect an individual.
  • Q-fever microorganisms may survive on surfaces up to 60 days (like sporulating bacteria).
  • According to WHO estimates[4], an amount of 50 kg of C. burnetii if spread in an area of 2 square kilometers is capable of:
  • Infecting 500,000 humans
  • Killing 150 individuals
  • Causing acute illness in 125,000 individuals
  • Causing chronic illness in 9,000 individuals

Microscopic pathology

Coxiella brutenii
Immunohistochemical detection of Coxiella burnetii in resected cardiac valve of a 60-year-old man with Q fever - By Mahamat A, Edouard S, Demar M, Abboud P, Patrice J-Y, La Scola B, et al. -Public domain-, via Wikime

References

  1. ↑ Marrie TJ (1990). "Q fever - a review". Can. Vet. J. 31 (8): 555–63. PMC 1480833. PMID 17423643.
  2. ↑ "Diagnosis of Q Fever".
  3. ↑ Choyce DP (1992). "Anterior chamber lens exchange". J Cataract Refract Surg. 18 (5): 537. PMID 1489455.
  4. ↑ "apps.who.int" (PDF).
  5. ↑ "Q Fever on JSTOR".

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