Phycomycosis
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Phycomycosis is an uncommon condition affecting the
gastrointestinal tract The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the Digestion, digestive system that leads from the mouth to the anus. The tract is the largest of the body's systems, after the cardiovascula ...
and
skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other animal coverings, such as the arthropod exoskeleton, have different ...
, most commonly found in
dog The dog (''Canis familiaris'' or ''Canis lupus familiaris'') is a domesticated descendant of the gray wolf. Also called the domestic dog, it was selectively bred from a population of wolves during the Late Pleistocene by hunter-gatherers. ...
s and
horse The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 mi ...
s. The condition is caused by various
mold A mold () or mould () is one of the structures that certain fungus, fungi can form. The dust-like, colored appearance of molds is due to the formation of Spore#Fungi, spores containing Secondary metabolite#Fungal secondary metabolites, fungal ...
s (a type of
fungi A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...
), with individual forms including pythiosis, zygomycosis, and lagenidiosis. Pythiosis, the most common type, is caused by ''
Pythium ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but '' Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are fre ...
'', a type of
water mould The Oomycetes (), or Oomycota, form a distinct phylogenetic lineage of fungus-like eukaryotic microorganisms within the Stramenopiles. They are filamentous and heterotrophic, and can reproduce both sexually and asexually. Sexual reproduction o ...
. Zygomycosis can be caused by two types of
zygomycetes Zygomycota, or zygote fungi, is a former division or phylum of the kingdom Fungi. The members are now part of two phyla: the Mucoromycota and Zoopagomycota. Approximately 1060 species are known. They are mostly terrestrial in habitat, living ...
: ''
Entomophthorales The Entomophthorales are an order of fungi that were previously classified in the class Zygomycetes. A new subdivision, Entomophthoromycotina, in 2007, was circumscribed for them. Most species of the entomophthorales are pathogens of insects ...
'' (e.g., '' Basidiobolus'' and '' Conidiobolus'') and ''
Mucorales The Mucorales is the largest and best-studied order of zygomycete fungi. Members of this order are sometimes called pin molds. The term mucormycosis is now preferred for infections caused by molds belonging to the order Mucorales. Systematic ...
'' (e.g., ''
Mucor ''Mucor'' is a microbial genus of approximately 40 species of molds and dimorphic fungi in the family Mucoraceae. The genus includes both pathogenic and avirulent species, and some members of it can be utilized in biotechnical applications. ...
'', '' Mortierella'', ''
Absidia ''Absidia'' is a genus of fungi in the family Cunninghamellaceae. ''Absidia'' species are ubiquitous in most environments where they are often associated with warm decaying plant matter, such as compost heaps. Some species in the genus can caus ...
'', ''
Rhizopus ''Rhizopus'' is a genus of common saprophytic fungi on plants and specialized parasites on animals. They are found in a wide variety of organic substances, including "mature fruits and vegetables", jellies, syrups, leather, bread, peanuts, and t ...
'', '' Rhizomucor'', and '' Saksenaea''). The latter type of zygomycosis is also referred to as
mucormycosis Mucormycosis, also known as black fungus, is a severe fungal infection that comes under fulminant fungal sinusitis, usually in people who are immunocompromised. It is curable only when diagnosed early. Symptoms depend on where in the body the ...
. Lagenidiosis is caused by a '' Lagenidium'' species, which like ''Pythium'' is a water mould. Since both pythiosis and lagenidiosis are caused by organisms from the
Oomycete The Oomycetes (), or Oomycota, form a distinct phylogenetic lineage of fungus-like eukaryotic microorganisms within the Stramenopiles. They are filamentous and heterotrophic, and can reproduce both sexually and asexually. Sexual reproduction o ...
s and not the kingdom fungi, they are sometimes collectively referred to as oomycosis.


Pythiosis

Pythiosis is caused by ''
Pythium insidiosum ''Pythium insidiosum'' is a species of '' Pythium'' and a member of the class oomycota. ''Pythium insidiosum'' is mainly found in standing water and occasionally soil. Unlike most ''Pythium'' species, which are generally pathogens of terrestria ...
'' and occurs most commonly in dogs and
horse The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 mi ...
s, but is also found in
cat The cat (''Felis catus''), also referred to as the domestic cat or house cat, is a small domesticated carnivorous mammal. It is the only domesticated species of the family Felidae. Advances in archaeology and genetics have shown that the ...
s,
cattle Cattle (''Bos taurus'') are large, domesticated, bovid ungulates widely kept as livestock. They are prominent modern members of the subfamily Bovinae and the most widespread species of the genus '' Bos''. Mature female cattle are calle ...
, and humans. In the United States, it is most commonly found in states bordering the Gulf of Mexico , especially
Louisiana Louisiana ( ; ; ) is a state in the Deep South and South Central regions of the United States. It borders Texas to the west, Arkansas to the north, and Mississippi to the east. Of the 50 U.S. states, it ranks 31st in area and 25 ...
, but has been found in the Midwest and Eastern states. It is also found in
Southeast Asia Southeast Asia is the geographical United Nations geoscheme for Asia#South-eastern Asia, southeastern region of Asia, consisting of the regions that are situated south of China, east of the Indian subcontinent, and northwest of the Mainland Au ...
, eastern
Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...
,
New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...
, and
South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...
. Pythiosis occurs in areas with mild winters due to the organism surviving in standing water that does not reach freezing temperatures. ''Pythium'' occupies swamps in late summer and infects dogs who drink water containing it. The disease is typically found in young, large breed dogs. It is suspected that pythiosis is caused by invasion of the organism into wounds, either in the skin or in the gastrointestinal tract. The disease grows slowly in the
stomach The stomach is a muscular, hollow organ in the upper gastrointestinal tract of Human, humans and many other animals, including several invertebrates. The Ancient Greek name for the stomach is ''gaster'' which is used as ''gastric'' in medical t ...
and
small intestine The small intestine or small bowel is an organ (anatomy), organ in the human gastrointestinal tract, gastrointestinal tract where most of the #Absorption, absorption of nutrients from food takes place. It lies between the stomach and large intes ...
, eventually forming large lumps of
granulation tissue Granulation tissue is new connective tissue and microscopic blood vessels that form on the surfaces of a wound during the healing process. Granulation tissue typically grows from the base of a wound and is able to fill wounds of almost any size ...
. It can also invade surrounding
lymph node A lymph node, or lymph gland, is a kidney-shaped organ of the lymphatic system and the adaptive immune system. A large number of lymph nodes are linked throughout the body by the lymphatic vessels. They are major sites of lymphocytes that includ ...
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 An ulcer is a discontinuity or break in a bodily membrane that impedes normal function of the affected organ. According to Robbins's pathology, "ulcer is the breach of the continuity of skin, epithelium or mucous membrane caused by sloughin ...
ated lumps. Primary infection can also occur in the bones and lungs. In horses, subcutaneous pythiosis is the most common form and infection occurs through a wound while standing in water containing the pathogen. 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 A granuloma is an aggregation of macrophages (along with other cells) that forms in response to chronic inflammation. This occurs when the immune system attempts to isolate foreign substances that it is otherwise unable to eliminate. Such sub ...
tous and itchy, and may be ulcerated or
fistula In anatomy, a fistula (: fistulas or fistulae ; from Latin ''fistula'', "tube, pipe") is an abnormal connection (i.e. tube) joining two hollow spaces (technically, two epithelialized surfaces), such as blood vessels, intestines, or other h ...
ted. The lesions often contain yellow, firm masses of dead tissue known as kunkers. It is possible with chronic infection, the disease can spread to underlying bone. In cats, pythioisis is almost always confined to the skin as hairless and edematous lesions. It is usually found on the limbs,
perineum The perineum (: perineums or perinea) in placentalia, placental mammals is the space between the anus and the genitals. The human perineum is between the anus and scrotum in the male or between the anus and vulva in the female. The perineum is ...
, and at the base of the tail. Lesions may also develop in the
nasopharynx The pharynx (: pharynges) is the part of the throat behind the mouth and nasal cavity, and above the esophagus and trachea (the tubes going down to the stomach and the lungs respectively). It is found in vertebrates and invertebrates, though its ...
. In humans, it can cause
arteritis Arteritis is a vascular disorder characterized by inflammation of the walls of arteries, usually as a result of infection or autoimmune responses. Arteritis, a complex disorder, is still not entirely understood. Arteritis may be distinguished b ...
,
keratitis Keratitis is a condition in which the human eye, eye's cornea, the clear dome on the front surface of the eye, becomes inflammation, inflamed. The condition is often marked by moderate to intense pain and usually involves any of the following sy ...
, and
periorbital The periorbita is the area around the orbit. Sometimes it refers specifically to the layer of tissue surrounding the orbit that consists of periosteum The periosteum is a membrane that covers the outer surface of all bones, except at the articu ...
cellulitis Cellulitis is usually a bacterial infection involving the inner layers of the skin. It specifically affects the dermis and subcutaneous fat. Signs and symptoms include an area of redness which increases in size over a few days. The borders of ...
. ''Pythium insidiosum'' is different from other members of the genus in that human and horse hair, skin, and decaying animal tissue are
chemoattractant Chemotaxis (from '' chemo-'' + ''taxis'') is the movement of an organism or entity in response to a chemical stimulus. Somatic cells, bacteria, and other single-cell or multicellular organisms direct their movements according to certain chemica ...
s for its
zoospore A zoospore is a motile asexual spore that uses a flagellum for locomotion in aqueous or moist environments. Also called a swarm spore, these spores are created by some protists, bacteria, and fungi to propagate themselves. Certain zoospores are ...
s, in addition to decaying plant tissue.


Zygomycosis

Usually, zygomycosis is a disease of the skin, but can also occur in the sinuses or gastrointestinal tract. In humans, it is most prevalent in immunocompromised patients (human immunodeficiency virus/acquired immunodeficiency syndrome HIV/AIDS/nowiki>">AIDS.html" ;"title="nowiki/>AIDS">HIV/AIDS/nowiki>, the old age">elderly Old age is the range of ages for people nearing and surpassing life expectancy. People who are of old age are also referred to as: old people, elderly, elders, senior citizens, seniors or older adults. Old age is not a definite biological sta ...
, severe combined immunodeficiency SCID/nowiki>">nowiki/>Severe combined immunodeficiency">SCID/nowiki>, 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 Immunodeficiency, also known as immunocompromise, is a state in which the immune system's ability to fight infectious diseases and cancer is compromised or entirely absent. Most cases are acquired ("secondary") due to extrinsic factors that affe ...
 animals. ''Entomophthorales'' cause chronic, local infections in otherwise healthy animals. The important species that causes 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. Horses are one of the most common domestic animals to be affected by entomophthoromycosis. ''C. coronatus'' causes lesions in the nasal and oral
mucosa A mucous membrane or mucosa is a membrane that lines various cavities in the body of an organism and covers the surface of internal organs. It consists of one or more layers of epithelial cells overlying a layer of loose connective tissue. It ...
of horses that may cause nasal discharge or difficulty breathing. ''B. ranarum'' causes large circular nodules on the upper body and neck of horses. ''Entomophthorales'' is found in soil and decaying plant matter, and specifically, ''Basidiobolus'' can be contracted from insects and the feces of reptiles or amphibians. Zygomycosis of the sinuses can extend from the sinuses into the orbit and the cranial vault, leading to rhinocerebral mucormycosis.


Lagenidiosis

The best known species of ''Lagenidium'' is '' Lagenidium giganteum'', a parasite of ''mosquito'' larvae used in the
biological control Biological control or biocontrol is a method of controlling pests, whether pest animals such as insects and mites, weeds, or pathogens affecting animals or plants by using other organisms. It relies on predation, parasitism, herbivory, or o ...
of mosquitoes. Two different species cause disease exclusively 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 tracts. Regional lymph nodes are usually swollen. Spread of the disease to distant lymph nodes, large blood vessels, and the lungs may occur. An
aneurysm An aneurysm is an outward :wikt:bulge, bulging, likened to a bubble or balloon, caused by a localized, abnormal, weak spot on a blood vessel wall. Aneurysms may be a result of a hereditary condition or an acquired disease. Aneurysms can also b ...
of a
great vessel Great vessels are the large vessels that bring blood to and from the heart. These are: * Superior vena cava * Inferior vena cava * Pulmonary arteries * Pulmonary veins * Aorta Transposition of the great vessels is a group of congenital A bir ...
can rupture and cause sudden death. ''L. caninum'' is the more aggressive species and is more likely to spread to other organs than ''L. karlingii''.


Diagnosis and treatment

Diagnosis is through
biopsy A biopsy is a medical test commonly performed by a surgeon, interventional radiologist, an interventional radiologist, or an interventional cardiology, interventional cardiologist. The process involves the extraction of sampling (medicine), sample ...
or
culture Culture ( ) is a concept that encompasses the social behavior, institutions, and Social norm, norms found in human societies, as well as the knowledge, beliefs, arts, laws, Social norm, customs, capabilities, Attitude (psychology), attitudes ...
, although an enzyme-linked immunosorbent assay (
ELISA The enzyme-linked immunosorbent assay (ELISA) (, ) is a commonly used analytical biochemistry assay, first described by Eva Engvall and Peter Perlmann in 1971. The assay is a solid-phase type of enzyme immunoassay (EIA) to detect the presence of ...
) test has been developed for ''Pythium insidiosum'' in animals. Treatment is very difficult and includes
surgery Surgery is a medical specialty that uses manual and instrumental techniques to diagnose or treat pathological conditions (e.g., trauma, disease, injury, malignancy), to alter bodily functions (e.g., malabsorption created by bariatric surgery s ...
when possible. Postoperative recurrence is common.
Antifungal drug An antifungal medication, also known as an antimycotic medication, is a pharmaceutical fungicide or fungistatic used to treat and prevent mycosis such as athlete's foot, ringworm, candidiasis (thrush), serious systemic infections such as c ...
s show only limited effect on the disease, but
itraconazole Itraconazole, sometimes abbreviated ITZ, is an antifungal medication used to treat a number of fungal infections. This includes aspergillosis, blastomycosis, coccidioidomycosis, histoplasmosis, and paracoccidioidomycosis. It may be given ...
and terbinafine hydrochloride are often used for 2 to 3 months following surgery. Humans with ''Basidiobolus'' infections have been treated with
amphotericin B Amphotericin B is an antifungal medication used for serious fungal infections and leishmaniasis. The fungal infections it is used to treat include mucormycosis, aspergillosis, blastomycosis, candidiasis, coccidioidomycosis, and cryptococ ...
and
potassium iodide Potassium iodide is a chemical compound, medication, and dietary supplement. It is a medication used for treating hyperthyroidism, in radiation emergencies, and for protecting the thyroid gland when certain types of radiopharmaceuticals are u ...
. For pythiosis and lagenidiosis, a new drug targeting water moulds called
caspofungin Caspofungin ( INN; brand name Cancidas) is a lipopeptide antifungal drug from Merck & Co., Inc. It is a member of a class of antifungals termed the echinocandins. It works by inhibiting the enzyme (1→3)-β-D-glucan synthase and thereby di ...
is available, but it is very expensive.
Immunotherapy Immunotherapy or biological therapy is the treatment of disease by activating or suppressing the immune system. Immunotherapies designed to elicit or amplify an immune response are classified as ''activation immunotherapies,'' while immunotherap ...
has been used successfully in humans and horses with pythiosis. The
prognosis Prognosis ( Greek: πρόγνωσις "fore-knowing, foreseeing"; : prognoses) is a medical term for predicting the likelihood or expected development of a disease, including whether the signs and symptoms will improve or worsen (and how quickly) ...
for any type of phycomycosis is poor.


References


External links


''Oomycosis: Pythiosis in the Dog, Horse and Cat and Lagenidiosis in the Dog''
{{Medical resources , ICD11 = , ICD10 = {{ICD10, B, 46, , b, 35 , ICD10CM = , ICD9 = {{ICD9, 117.7 , ICDO = , OMIM = , DiseasesDB = 31329 , Curlie = , MedlinePlus = , eMedicineSubj = , eMedicineTopic = , PatientUK = , MeshID = D020096 , GeneReviewsNBK = , GeneReviewsName = , NORD = , GARDNum = , GARDName = , Orphanet = , AO = , RP = , WO = , OrthoInfo = , NCI = , Scholia = , SNOMED CT = Dog diseases Gastroenterology Animal fungal diseases