Title: Phycomycosis

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'''Phycomycosis''' is an uncommon condition affecting the [[gastrointestinal tract]] and [[skin]], most commonly found in [[dog]]s and [[horse]]s. The condition is caused by various [[Mold (fungus)|mold]]s (a type of [[fungus|fungi]]), including pythiosis, zygomycosis, and lagenidiosis. Pythiosis, the most common type, is caused by ''[[Pythium]]'', a type of [[oomycete|water mold]].  Zygomycosis can be caused by two types of [[zygomycota|zygomycetes]]: ''[[Entomophthorales]]'' (e.g., ''[[Basidiobolus]]'' and ''[[Conidiobolus]]'') and ''[[Mucorales]]'' (e.g., ''[[Mucor]]'', ''[[Mortierella]]'', ''[[Absidia]]'', ''[[Rhizopus]]'', ''[[Rhizomucor]]'', and ''[[Saksenaea]]'').&lt;ref name=Ettinger_1995&gt;{{cite book|author=Ettinger, Stephen J.|author2=Feldman, Edward C.|title=Textbook of Veterinary Internal Medicine|edition= 4th|publisher=W.B. Saunders Company|year=1995|isbn=0-7216-6795-3}}&lt;/ref&gt; The latter type of zygomycosis is also referred to as [[mucormycosis]]. Lagenidiosis is caused by a ''[[Lagenidium]]'' species, which, like Pythium, is a kind of water mold.  Since both pythiosis and lagenidiosis are caused by organisms from the [[Oomycete]]s and not the Fungi kingdom, they are sometimes collectively referred to as oomycosis.

==Pythiosis==
[[Image:Pythiosis 2.jpg|thumb|Ulcerative and destructive skin lesion on a dog caused by Pythium insidiosum]]
Pythiosis is caused by ''[[Pythium insidiosum]]'' and occurs most commonly in dogs and [[horse]]s, but is also found in [[cat]]s, [[cow|cattle]], and humans. In the United States, it is most commonly found in states bordering the Gulf of Mexico, especially [[Louisiana]], but has been found in the Midwest and Eastern states as well.  It is also found in [[Southeast Asia]], eastern [[Australia]], [[New Zealand]], and [[South America]].  Pythiosis occurs in areas with mild winters due to the organism surviving in standing water that does not reach freezing temperatures.&lt;ref name=Helman&gt;{{cite journal |vauthors=Helman R, Oliver J |title=Pythiosis of the digestive tract in dogs from Oklahoma |journal=J Am Anim Hosp Assoc |volume=35 |issue=2 |pages=111–4 |year=1999 |pmid=10102178 |doi=10.5326/15473317-35-2-111 }}&lt;/ref&gt;  ''Pythium'' occupies swamps in late summer and infects dogs who drink water containing it.  The disease is typically found in young, large-breed dogs.&lt;ref name=Ettinger_1995/&gt;

It is suspected that pythiosis is caused by the invasion of the organism into wounds, either in the skin or in the gastrointestinal tract.&lt;ref name=Helman/&gt;  The disease grows slowly in the [[stomach]] and [[small intestine]], eventually forming large lumps of [[granulation tissue]]. It can also invade surrounding [[lymph node]]s. Symptoms include vomiting, diarrhea, weight loss, a mass in the abdomen, and depression. Pythiosis of the skin in dogs is very rare and appears as [[ulcer]]ated lumps. Primary infection can also occur in the bones and lungs.

[[Image:Pythiosis hyphae.jpg|thumb|left|''Pythium'' hyphae]]
In horses, [[subcutis|subcutaneous]] pythiosis is the most common form. Infection occurs through a wound while standing in water containing the pathogen.&lt;ref name=Liljebjelke&gt;{{cite journal |vauthors=Liljebjelke K, Abramson C, Brockus C, Greene C |title=Duodenal obstruction caused by infection with Pythium insidiosum in a 12-week-old puppy |journal=J Am Vet Med Assoc |volume=220 |issue=8 |pages=1188–91, 1162 |year=2002 |pmid=11990966 |doi=10.2460/javma.2002.220.1188 |doi-access=free }}&lt;/ref&gt; The disease is also known as leeches, swamp cancer, and bursatti. Lesions are most commonly found on the lower limbs, abdomen, chest, and genitals. They are [[granuloma]]tous and itchy, and may be ulcerated or [[fistula]]ted. The lesions often contain yellow, firm masses of dead tissue known as kunkers.&lt;ref name=Merck_oo&gt;{{cite web | title = Oomycosis | work = The Merck Veterinary Manual | date = 2006 | url = http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/51112.htm | accessdate = 2007-02-03 }}&lt;/ref&gt; For cases with chronic infection, it is possible for the disease to spread to underlying bone.&lt;ref&gt;{{cite journal |vauthors=Worster A, Lillich J, Cox J, Rush B |title=Pythiosis with bone lesions in a pregnant mare |journal=J Am Vet Med Assoc |volume=216 |issue=11 |pages=1795–8, 1760 |year=2000 |pmid=10844973 |doi=10.2460/javma.2000.216.1795 |doi-access=free }}&lt;/ref&gt;

In cats, pythioisis is almost always confined to the skin as hairless and edematous lesions. It is usually found on the limbs, [[perineum]], and at the base of the tail.&lt;ref name=&quot;Wolf_2005&quot;&gt;{{cite book|editor=August, John R.|chapter=Opportunistic fungal infections|author=Wolf, Alice|title=Consultations in Feline Internal Medicine Vol. 5|publisher=Elsevier Saunders|year=2005|isbn=0-7216-0423-4}}&lt;/ref&gt;  Lesions may also develop in the [[nasopharynx]].&lt;ref name=&quot;Merck_oo&quot; /&gt;

In humans, it can cause [[arteritis]], [[keratitis]], and [[periorbital]] [[cellulitis]].&lt;ref name=&quot;Grooters_2003&quot;&gt;{{cite journal |author=Grooters A |year=2003 |title=Pythiosis, lagenidiosis, and zygomycosis in small animals |journal=Vet Clin North Am Small Anim Pract |volume=33 |issue=4 |pages=695–720, v |doi=10.1016/S0195-5616(03)00034-2 |pmid=12910739}}&lt;/ref&gt;

''Pythium insidiosum'' is different from other members of the genus in that human and horse hair, skin, and decaying animal tissue are [[chemoattractant]]s for its [[zoospore]]s, in addition to decaying plant tissue.&lt;ref name=Liljebjelke/&gt;

==Zygomycosis==
{{For|Basidiobolus infection in humans (basidiobolomycosis)|Basidiobolus ranarum}}
{{For|Mucorales infection in humans|Mucormycosis}}
[[Image:Mature_sporangium_of_a_Mucor_sp._fungus.jpg|thumb|A mature [[sporangium]] of a ''Mucor'' sp. fungus]]
Zygomycosis is most often a disease of the skin, but can also occur in the sinuses or gastrointestinal tract. In humans, it is most prevalent in immunocompromised patients (people living with [[AIDS|HIV/AIDS]], the [[old age|elderly]], people with [[severe combined immunodeficiency]], etc.) and patients with acidosis (i.e., diabetes, burns), particularly after barrier injury to the skin or mucous membranes. Zygomycosis caused by ''Mucorales'' causes a rapidly progressing disease of sudden onset in sick or [[immunodeficiency|immunocompromised]] animals. ''Entomophthorales'' caused chronic, local infections in otherwise healthy animals. The important species that cause entomophthoromycosis are ''Conidiobolus coronatus'', ''C. incongruous'', and ''[[Basidiobolus ranarum]]''. ''Conidiobolus'' infections of the upper respiratory system have been reported in humans, sheep, horses, and dogs, and ''Basidiobolus'' has been reported less commonly in humans and dogs.&lt;ref name=Greene&gt;{{cite journal |vauthors=Greene C, Brockus C, Currin M, Jones C |title=Infection with Basidiobolus ranarum in two dogs |journal=J Am Vet Med Assoc |volume=221 |issue=4 |pages=528–32, 500 |year=2002 |pmid=12184703 |doi=10.2460/javma.2002.221.528 |doi-access=free }}&lt;/ref&gt; Horses are one of the most common domestic animals to be affected by entomophthoromycosis. ''C. coronatus'' causes lesions in the nasal and oral [[mucous membrane|mucosa]] of horses that may cause nasal discharge or difficulty breathing. ''B. ranarum'' causes large circular nodules on the upper body and neck of horses.&lt;ref&gt;{{cite web | title = Zygomycosis | work = The Merck Veterinary Manual | date = 2006 | url = http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/51118.htm | accessdate = 2007-02-03 }}&lt;/ref&gt; ''Entomophthorales'' is found in soil and decaying plant matter, and, specifically, ''Basidiobolus'' can be contracted from insects and the feces of reptiles or amphibians.&lt;ref name=Grooters_2003/&gt;

Zygomycosis of the sinuses can extend from the sinuses into the orbit and the cranial vault, leading to rhinocerebral mucormycosis.{{cn|date=February 2023}}

==Lagenidiosis==
The best known species of ''Lagenidium'' is ''[[Lagenidium giganteum]]'', a parasite of ''mosquito'' larvae used in the [[biological pest control|biological control]] of mosquitoes. Two different species exclusively cause disease in dogs: ''L. caninum'' and ''L. karlingii''.  ''Lagenidium'' is found in the Southeastern United States in lakes and ponds.  Lagenidiosis causes progressive skin and subcutaneous lesions in the legs, groin, trunk, and near the tail. The lesions are firm nodules or ulcerated regions with [[draining tract]]s. Regional lymph nodes are usually swollen. Spread of the disease to distant lymph nodes, large blood vessels, and the lungs may occur.&lt;ref name=Grooters_2003/&gt;  An [[aneurysm]] of a [[great vessels|great vessel]] can rupture and cause death.&lt;ref name=Merck_oo/&gt;  ''L. caninum'' is the more aggressive species and is more likely to spread to other organs than ''L. karlingii''.&lt;ref name=forum&gt;{{cite journal | last = Todd-Jenkins | first = Karen | title = A new disease: clinically interesting for all the right reasons | journal = Veterinary Forum | volume = 24 | issue = 9 | pages = 18–20 | publisher = Veterinary Learning Systems | date = September 2007 }}&lt;/ref&gt;

==Diagnosis and treatment==
Diagnosis is through [[biopsy]], [[microbiological culture|culture]] or an enzyme-linked immunosorbent assay ([[ELISA]]) test.&lt;ref name=Hensel&gt;{{cite journal |vauthors=Hensel P, Greene C, Medleau L, Latimer K, Mendoza L |title=Immunotherapy for treatment of multicentric cutaneous pythiosis in a dog |journal=J Am Vet Med Assoc |volume=223 |issue=2 |pages=215–8, 197 |year=2003 |pmid=12875449 |doi=10.2460/javma.2003.223.215 }}&lt;/ref&gt; Treatment is very difficult and includes [[surgery]] when possible. Postoperative recurrence is common. [[Antifungal drug]]s show only limited effect on the disease, but [[itraconazole]] and [[terbinafine|terbinafine hydrochloride]] are often used for 2 to 3 months following surgery.&lt;ref name=Grooters_2003/&gt; Humans with ''Basidiobolus'' infections have been treated with [[amphotericin B]] and [[potassium iodide]].&lt;ref name=Greene/&gt; For pythiosis and lagenidiosis, a drug targeting water molds called [[caspofungin]] is available, although its high cost makes its usage to be rare.&lt;ref name=Grooters_2003/&gt;  [[Immunotherapy]] has been used successfully in humans and horses with pythiosis.&lt;ref name=Hensel/&gt;  The [[prognosis]] for any type of phycomycosis is poor.

==References==
{{Reflist}}

==External links==
* [http://www.vet.uga.edu/VPP/clerk/stephens/index.htm ''Oomycosis: Pythiosis in the Dog, Horse and Cat and Lagenidiosis in the Dog'']

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[[Category:Dog diseases]]
[[Category:Gastroenterology]]
[[Category:Animal fungal diseases]]