Coccidioidomycosis pathophysiology: Difference between revisions

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{{Coccidioidomycosis}}
{{Coccidioidomycosis}}
{{CMG}}
{{CMG}}; {{AE}}; {{VB}}; {{ADG}}
==Overview==
[[Coccidioidomycosis]] is a [[fungal]] [[infection]], that is acquired through [[inhalation]] of the [[spores]] that is present in the environment. Following transmission, [[coccidioidomycosis]] are deposited into termina[[Bronchioles|l bronchioles]] and enlarge, become rounded and develop internal septations to form what are known as the spherules. It then disseminates to the [[lymphatics]] and [[blood]] stream to gain access to any organ of the body.<ref name="pmid26739609">{{cite journal |vauthors=Stockamp NW, Thompson GR |title=Coccidioidomycosis |journal=Infect. Dis. Clin. North Am. |volume=30 |issue=1 |pages=229–46 |year=2016 |pmid=26739609 |doi=10.1016/j.idc.2015.10.008 |url=}}</ref><ref name="pmid26398540">{{cite journal |vauthors=Twarog M, Thompson GR |title=Coccidioidomycosis: Recent Updates |journal=Semin Respir Crit Care Med |volume=36 |issue=5 |pages=746–55 |year=2015 |pmid=26398540 |doi=10.1055/s-0035-1562900 |url=}}</ref><ref name="pmid25577855">{{cite journal |vauthors=DiCaudo DJ |title=Coccidioidomycosis |journal=Semin Cutan Med Surg |volume=33 |issue=3 |pages=140–5 |year=2014 |pmid=25577855 |doi= |url=}}</ref><ref name="pmid24575994">{{cite journal |vauthors=Malo J, Luraschi-Monjagatta C, Wolk DM, Thompson R, Hage CA, Knox KS |title=Update on the diagnosis of pulmonary coccidioidomycosis |journal=Ann Am Thorac Soc |volume=11 |issue=2 |pages=243–53 |year=2014 |pmid=24575994 |doi=10.1513/AnnalsATS.201308-286FR |url=}}</ref>


==Pathophysiology==
==Pathogenesis==
''C. immitis'' resides in the soil in certain parts of the southwestern [[United States]], northern Mexico, and parts of Central and South America [http://www.mayoclinic.com/print/valley-fever/DS00695/DSECTION=all&METHOD=print].   It is dormant during long dry spells, then develops as a mold with long filaments that break off into airborne spores when the rains come.  The spores, known as [[arthroconidia]], are swept into the air by disruption of the soil, such as during construction or farming. Infection is caused by inhalation of the particles. The disease is not transmitted from person to person. ''C. immitis'' is a dimorphic saprophytic organism that grows as a [[mycelium]] in the soil and produces a spherule form in the host organism.
The pathogenesis of coccidioidomycosis can be described in following steps.<ref name="pmid26739609">{{cite journal |vauthors=Stockamp NW, Thompson GR |title=Coccidioidomycosis |journal=Infect. Dis. Clin. North Am. |volume=30 |issue=1 |pages=229–46 |year=2016 |pmid=26739609 |doi=10.1016/j.idc.2015.10.008 |url=}}</ref><ref name="pmid26398540">{{cite journal |vauthors=Twarog M, Thompson GR |title=Coccidioidomycosis: Recent Updates |journal=Semin Respir Crit Care Med |volume=36 |issue=5 |pages=746–55 |year=2015 |pmid=26398540 |doi=10.1055/s-0035-1562900 |url=}}</ref><ref name="pmid25577855">{{cite journal |vauthors=DiCaudo DJ |title=Coccidioidomycosis |journal=Semin Cutan Med Surg |volume=33 |issue=3 |pages=140–5 |year=2014 |pmid=25577855 |doi= |url=}}</ref><ref name="pmid24575994">{{cite journal |vauthors=Malo J, Luraschi-Monjagatta C, Wolk DM, Thompson R, Hage CA, Knox KS |title=Update on the diagnosis of pulmonary coccidioidomycosis |journal=Ann Am Thorac Soc |volume=11 |issue=2 |pages=243–53 |year=2014 |pmid=24575994 |doi=10.1513/AnnalsATS.201308-286FR |url=}}</ref>
[[Image:Coccidioidomycosis-lifecycle.jpg|center|thumb|Life cycle and epidemiology - Source: https://www.cdc.gov/]]
===Transmission===
*Coccidioiodomycosis exist as mycelia in the soil with septations.
*During hot climate or dry environment, they proliferate asexually, transforming into spores, known as [[arthroconidia]].  
*[[Infection]] is caused by [[inhalation]] of these [[arthroconidia]].
*The disease is not transmitted from person to person.
===Incubation period===
*Incubation period of coccidioidomycosis varies from one to three weeks.
===Dissemination===
*Following inhalation, [[arthroconidia]] reach terminal [[bronchioles]].
*Then they are ingested by [[Macrophages|pulmonary macrophages]].
*Inside [[macrophages]] these [[arthroconidia]] enlarge, become rounded and develop internal septations to form what are known as the spherules.
*It then disseminates to the [[lymphatics]] and [[blood]] stream to gain access to any organ of the body.
===Seeding===
*Spherules contain uni-nuclear cells called as [[endospores]] which may propagate the infection further as they have the capability to develop into spherules.
*This conversion of [[arthroconidia]] into spherules initiates an [[Inflammatory response|inflammatory reaction]] and leads to a chemotaxic response (peptides derived from activation of the [[Complement System|complement pathway]], [[leukotrienes]] ) which attracts [[neutrophils]] and [[eosinophils]] to the site of [[inflammation]].
*[[Cell-mediated immunity|Cell mediated immunity]] keeps the [[infection]] in check and keeps them limited to the organ of origin by forming [[Granulomas|granulomas.]]
===Immune response===
Coccidioidomycosis elicits [[Cell-mediated immune response|cell-mediated immune responses]].
*[[Hypersensitivity|Delayed type hypersensitivity]] to coccidioidal [[antigens]] is common after acute infection has resolved.
*Dissemination usually occurs via the l[[Lymphatic system|ymphatic]]<nowiki/>s and is more common in [[immune]] suppressed in whom the primary [[infection]] is not contained.


Once inside a susceptible host the anthroconidia enlarge, become rounded and develop internal septations to form what are known as the spherules. These contain uni-nuclear cells called as endospores which may propagate the infection further as they have the capability to develop into spherules. This conversion of anthroconidia into spherules initiates an inflammatory reaction and leads to a chemotaxic response which attracts neutrophils and eosinophils to the site of inflammation. Cell mediated immunity keeps the infection in check and keeps them limited to the organ of origin by forming granulomas. Delayed type hypersensitivity to coccidioidal antigens is common after acute infection has resolved. Dissemination usually occurs via the lymphatics and is more common in immune suppressed in whom the primary infection is not contained.


The infection starts in the lungs. There are three forms of coccidioidomycosis: acute, chronic, or disseminated.
[[Image:Life cycle of coccidioides.svg.png|center|Life cycle of coccidiodes|788x788px]]
* Acute pulmonary coccidioidomycosis. It almost always mild, with few or no symptoms, and goes away without treatment. The incubation period -- the time between breathing in the spores and becoming sick -- is 7 to 21 days.
 
* Chronic pulmonary coccidioidomycosis can develop 20 or more years after initial infection. Infections (lung abscesses) can form and rupture, releasing pus (empyema) between the lungs and ribs (pleural space).
==Genetics==
* Disseminated coccidioidomycosis is a widespread form of the disease. Infection spreads to other parts of the body, including the skin, brain, bones, and heart. Meningitis occurs in up to half of all people with disseminated coccidioidomycosis.  
There is no known genetic association to coccidioidomycosis.
 
==Microscopic pathology==
It is a dimorphic fungus and on microscopy, the following can be seen
*Spherule with [[endospores]]
*Rarely as [[hyphae]] in lung biopsy
[[Image:Microscopy valley fever.jpg|center|Histopathological changes in coccidioidomycosis]]
 
<gallery>
Image: Coccidioidomycosis19.jpeg| Methenamine silver stain reveals reveals spherules of Coccidioides immitis in brain tissue. <SMALL><SMALL>''[http://phil.cdc.gov/phil/home.asp From Public Health Image Library (PHIL).] ''<ref name=PHIL> {{Cite web | title = Public Health Image Library (PHIL) | url = http://phil.cdc.gov/phil/home.asp}}</ref></SMALL></SMALL>
 
Image: Coccidioidomycosis07.jpeg| PAS-stained photomicrograph of an unknown tissue specimen revealed the presence of three Coccidioides immitis spherules. <SMALL><SMALL>''[http://phil.cdc.gov/phil/home.asp From Public Health Image Library (PHIL).] ''<ref name=PHIL> {{Cite web | title = Public Health Image Library (PHIL) | url = http://phil.cdc.gov/phil/home.asp}}</ref></SMALL></SMALL>
 
Image: Coccidioidomycosis06.jpeg| PAS-stained photomicrograph of an unknown tissue specimen revealed the presence of three Coccidioides immitis spherules. <SMALL><SMALL>''[http://phil.cdc.gov/phil/home.asp From Public Health Image Library (PHIL).] ''<ref name=PHIL> {{Cite web | title = Public Health Image Library (PHIL) | url = http://phil.cdc.gov/phil/home.asp}}</ref></SMALL></SMALL>
 
Image: Coccidioidomycosis05.jpeg| Photomicrograph of of pus from a Guinea pig, Cavia porcellus, reveals presence of numbers of Coccidioides sp. fungal sporangia.  <SMALL><SMALL>''[http://phil.cdc.gov/phil/home.asp From Public Health Image Library (PHIL).] ''<ref name=PHIL> {{Cite web | title = Public Health Image Library (PHIL) | url = http://phil.cdc.gov/phil/home.asp}}</ref></SMALL></SMALL>
 
Image: Coccidioidomycosis04.jpeg| Photomicrograph of of pus from a Guinea pig, Cavia porcellus, reveals presence of numbers of Coccidioides sp. fungal sporangia.  <SMALL><SMALL>''[http://phil.cdc.gov/phil/home.asp From Public Health Image Library (PHIL).] ''<ref name=PHIL> {{Cite web | title = Public Health Image Library (PHIL) | url = http://phil.cdc.gov/phil/home.asp}}</ref></SMALL></SMALL>
 
 
Image: Coccidioidomycosis15.jpeg| Histopathologic characteristics found within a pus specimen, prepared using potassium hudroxide (KOH). Specimen harvested from a skin lesion in a case of cutaneous coccidioidomycosis. <SMALL><SMALL>''[http://phil.cdc.gov/phil/home.asp From Public Health Image Library (PHIL).] ''<ref name=PHIL> {{Cite web | title = Public Health Image Library (PHIL) | url = http://phil.cdc.gov/phil/home.asp}}</ref></SMALL></SMALL>
 
Image: Coccidioidomycosis14.jpeg| Histopathologic characteristics found within a pus specimen, prepared using periodic acid-Schiff (PAS). Specimen harvested from a skin lesion in a case of cutaneous coccidioidomycosis. <SMALL><SMALL>''[http://phil.cdc.gov/phil/home.asp From Public Health Image Library (PHIL).] ''<ref name=PHIL> {{Cite web | title = Public Health Image Library (PHIL) | url = http://phil.cdc.gov/phil/home.asp}}</ref></SMALL></SMALL>
 
Image: Coccidioidomycosis12.jpeg| Histopathologic characteristics found within a pus specimen, prepared using periodic acid-Schiff (PAS). Specimen harvested from a skin lesion in a case of cutaneous coccidioidomycosis. <SMALL><SMALL>''[http://phil.cdc.gov/phil/home.asp From Public Health Image Library (PHIL).] ''<ref name=PHIL> {{Cite web | title = Public Health Image Library (PHIL) | url = http://phil.cdc.gov/phil/home.asp}}</ref></SMALL></SMALL>
Image: Coccidioidomycosis25.jpeg| Histopathology of coccidioidomycosis, lung. Methenamine silver stain. <SMALL><SMALL>''[http://phil.cdc.gov/phil/home.asp From Public Health Image Library (PHIL).] ''<ref name=PHIL> {{Cite web | title = Public Health Image Library (PHIL) | url = http://phil.cdc.gov/phil/home.asp}}</ref></SMALL></SMALL>
 
Image: Coccidioidomycosis24.jpeg| Histopathology of coccidioidomycosis, retroperitoneal area. <SMALL><SMALL>''[http://phil.cdc.gov/phil/home.asp From Public Health Image Library (PHIL).] ''<ref name=PHIL> {{Cite web | title = Public Health Image Library (PHIL) | url = http://phil.cdc.gov/phil/home.asp}}</ref></SMALL></SMALL>
 
Image: Coccidioidomycosis23.jpeg| Histopathologic changes due to coccidioidomycosis of the lung caused by Coccidioides immitis. <SMALL><SMALL>''[http://phil.cdc.gov/phil/home.asp From Public Health Image Library (PHIL).] ''<ref name=PHIL> {{Cite web | title = Public Health Image Library (PHIL) | url = http://phil.cdc.gov/phil/home.asp}}</ref></SMALL></SMALL>
 
Image: Coccidioidomycosis22.jpeg| Histopathologic changes in a case of coccidioidomycosis of the lung showing a large fibrocaseous nodule. <SMALL><SMALL>''[http://phil.cdc.gov/phil/home.asp From Public Health Image Library (PHIL).] ''<ref name=PHIL> {{Cite web | title = Public Health Image Library (PHIL) | url = http://phil.cdc.gov/phil/home.asp}}</ref></SMALL></SMALL>
 
Image: Coccidioidomycosis30.jpeg| Histopathology of coccidioidomycosis of lung. <SMALL><SMALL>''[http://phil.cdc.gov/phil/home.asp From Public Health Image Library (PHIL).] ''<ref name=PHIL> {{Cite web | title = Public Health Image Library (PHIL) | url = http://phil.cdc.gov/phil/home.asp}}</ref></SMALL></SMALL>
 
</gallery>


===Microscopic Pathology===
{{#ev:youtube|RtpvzCfFwfg}}
{{#ev:youtube|RtpvzCfFwfg}}


==References==
==References==
{{Reflist|2}}
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Latest revision as of 21:00, 29 July 2020

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: ; Vidit Bhargava, M.B.B.S [2]; Aditya Ganti M.B.B.S. [3]

Overview

Coccidioidomycosis is a fungal infection, that is acquired through inhalation of the spores that is present in the environment. Following transmission, coccidioidomycosis are deposited into terminal bronchioles and enlarge, become rounded and develop internal septations to form what are known as the spherules. It then disseminates to the lymphatics and blood stream to gain access to any organ of the body.[1][2][3][4]

Pathogenesis

The pathogenesis of coccidioidomycosis can be described in following steps.[1][2][3][4]

Life cycle and epidemiology - Source: https://www.cdc.gov/

Transmission

  • Coccidioiodomycosis exist as mycelia in the soil with septations.
  • During hot climate or dry environment, they proliferate asexually, transforming into spores, known as arthroconidia.
  • Infection is caused by inhalation of these arthroconidia.
  • The disease is not transmitted from person to person.

Incubation period

  • Incubation period of coccidioidomycosis varies from one to three weeks.

Dissemination

Seeding

Immune response

Coccidioidomycosis elicits cell-mediated immune responses.


Life cycle of coccidiodes
Life cycle of coccidiodes

Genetics

There is no known genetic association to coccidioidomycosis.

Microscopic pathology

It is a dimorphic fungus and on microscopy, the following can be seen

Histopathological changes in coccidioidomycosis
Histopathological changes in coccidioidomycosis

{{#ev:youtube|RtpvzCfFwfg}}

References

  1. ↑ 1.0 1.1 Stockamp NW, Thompson GR (2016). "Coccidioidomycosis". Infect. Dis. Clin. North Am. 30 (1): 229–46. doi:10.1016/j.idc.2015.10.008. PMID 26739609.
  2. ↑ 2.0 2.1 Twarog M, Thompson GR (2015). "Coccidioidomycosis: Recent Updates". Semin Respir Crit Care Med. 36 (5): 746–55. doi:10.1055/s-0035-1562900. PMID 26398540.
  3. ↑ 3.0 3.1 DiCaudo DJ (2014). "Coccidioidomycosis". Semin Cutan Med Surg. 33 (3): 140–5. PMID 25577855.
  4. ↑ 4.0 4.1 Malo J, Luraschi-Monjagatta C, Wolk DM, Thompson R, Hage CA, Knox KS (2014). "Update on the diagnosis of pulmonary coccidioidomycosis". Ann Am Thorac Soc. 11 (2): 243–53. doi:10.1513/AnnalsATS.201308-286FR. PMID 24575994.
  5. ↑ 5.00 5.01 5.02 5.03 5.04 5.05 5.06 5.07 5.08 5.09 5.10 5.11 5.12 "Public Health Image Library (PHIL)".

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