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'''Blastomycosis''' is a fungal infection caused by inhaling ''[[Blastomyces dermatitidis]]'' spores.
Blastomycosis
[[File:North American blastomycosis (5279534581).jpg|alt=North American blastomyclosis|thumb|North American blastomyclosis]]
== Definition ==


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{{Infobox disease
title='''{{PAGENAME}}'''
| name          = Blastomycosis
movie_url=http://www.youtube.com/v/t0VbR4duaOo
| image          = Blastomyces dermatitidis.jpg
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| caption        = Microscopic image of ''Blastomyces dermatitidis''
embed_source_url=http://www.youtube.com/v/t0VbR4duaOo
| field          = Infectious disease
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| symptoms      = Fever, cough, night sweats, muscle aches, joint pain, chest pain
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| complications  = Chronic pulmonary infection, disseminated disease
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| onset          = 3-15 weeks after exposure
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| duration      = Weeks to months
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| causes        = ''Blastomyces dermatitidis''
| risks          = Immunocompromised individuals, outdoor activities in endemic areas
| diagnosis      = Culture, histopathology, antigen detection
| treatment      = Antifungal medications (e.g., itraconazole, amphotericin B)
| prognosis      = Good with treatment
| frequency      = Rare
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Blastocystis is a common microscopic organism that inhabits the intestine and is found throughout the world.
==Overview==
A full understanding of the biology of Blastocystis and its relationship to other organisms is not clear, but is an active area of research. Infection with Blastocystis is called blastocystosis.
'''Blastomycosis''' is a [[fungal infection]] caused by the [[dimorphic fungus]] ''[[Blastomyces dermatitidis]]''. It primarily affects the [[lungs]] but can disseminate to other parts of the body, including the [[skin]], [[bones]], and [[central nervous system]]. The disease is endemic in certain regions of [[North America]], particularly in the [[Ohio]] and [[Mississippi River]] valleys, the [[Great Lakes]] region, and parts of [[Canada]].


== Signs and symptoms ==
==Etiology==
Watery or loose stools, diarrhea, abdominal pain, anal itching, weight loss, constipation, and excess gas have all been reported in persons with Blastocystis infection. Many people have no symptoms at all. The organism can be found in both well and sick persons.
The causative agent of blastomycosis is ''Blastomyces dermatitidis'', a fungus that exists in two forms: a mold form in the environment and a yeast form in the human body. The fungus is found in moist soil and decaying organic matter, such as wood and leaves.


Blastocystis can remain in the intestine for weeks, months, or years.
==Pathophysiology==
[[File:Blasto-map 600.jpg|alt= Distribution of blastomycosis in North America |thumb|Distribution of blastomycosis in North America ]]
Inhalation of the [[conidia]] (spores) of ''Blastomyces dermatitidis'' leads to infection. Once inhaled, the spores transform into yeast forms in the [[alveoli]] of the lungs. The yeast can evade the [[immune system]] and multiply, leading to pulmonary infection. In some cases, the infection can spread hematogenously to other organs.
== Cause ==
The role of Blastocystis in causing disease is controversial among experts. Some types of Blastocystis may be more likely to be associated with symptoms. Finding Blastocystis in stool samples should be followed up with a careful search for other possible causes of your symptoms.


== Incidence ==
==Clinical Manifestations==
Many people have Blastocystis in their intestine, some without ever having symptoms.
The clinical presentation of blastomycosis can vary widely. Common symptoms include:
* [[Fever]]
* [[Cough]]
* [[Night sweats]]
* [[Muscle aches]]
* [[Joint pain]]
* [[Chest pain]]


== Transmission ==
In cases of disseminated disease, patients may present with skin lesions, [[osteomyelitis]], or [[meningitis]].
How Blastocystis is transmitted is not known for certain, although the number of people infected seems to increase in areas where sanitation and personal hygiene is not adequate. Studies have suggested that risk of infection may increase through:
[[File:An introduction to dermatology (1905) blastomycosis.jpg|alt=Blastomycosis|thumb|'''Blastomycosis''']]
* ingesting contaminated food or water,
* exposure to a day care environment, or
* exposure to animals.
* How can I prevent infection with Blastocystis?
* Wash your hands with soap and warm water after using the toilet, changing diapers, and before handling food.
* Teach children the importance of washing hands to prevent infection.
* Avoid water or food that may be contaminated.
* Wash and peel all raw vegetables and fruits before eating.
* When traveling in countries where the water supply may be unsafe, avoid drinking unboiled tap water and avoid uncooked foods washed with unboiled tap water.
* Bottled or canned carbonated beverages, seltzers, pasteurized fruit drinks, and steaming hot coffee and tea are safe to drink.


== Treatment ==
==Diagnosis==
The clinical significance of Blastocystis spp. is controversial.
Diagnosis of blastomycosis is based on clinical suspicion, especially in patients with a history of exposure in endemic areas. Diagnostic methods include:
* [[Culture]] of the organism from clinical specimens
* [[Histopathology]] showing broad-based budding yeast
* [[Antigen detection]] in urine or serum


Treatment with metronidazole^ at various doses has been reported, for example (adults):
==Treatment==
The primary treatment for blastomycosis is antifungal therapy. The choice of medication depends on the severity of the disease:
* [[Itraconazole]] is the drug of choice for mild to moderate disease.
* [[Amphotericin B]] is used for severe or disseminated cases.


250 mg to 750 mg metronidazole^ orally 3 times daily for 10 days
==Prognosis==
1500 mg metronidazole^ orally once daily for 10 days
With appropriate treatment, the prognosis for blastomycosis is generally good. However, untreated or severe cases can lead to significant morbidity and mortality.
Note: Lack of response to metronidazole has been noted in some areas (Yakoob et al., Br J Biomed Sci 2004;61:75).
[[File:Blastomycosis of skin.tif|alt=Blastomycosis of skin|thumb|Blastomycosis of skin]]
Treatment with trimethoprim (TMP)^/sulfamethoxazole (SMX)^ at various doses has been reported, for example (adults):


6 mg/kg TMP^, 30 mg/kg SMX^ once daily for 7 days
==Prevention==
320mg TMP^, 1600 mg SMX^ once daily for 7 days
Preventive measures include avoiding activities that disturb soil in endemic areas, especially for immunocompromised individuals. There is currently no vaccine available for blastomycosis.
160 mg TMP^, 800 mg SMX^ twice daily for 7 days
Treatment with nitazoxanide^ has been shown to be effective in clearing organisms and improving symptoms at the following doses:


Adults, 500 mg nitazoxanide^ orally twice daily for 3 days.
==Epidemiology==
Children, 200 mg nitazoxanide^ orally twice daily for 3 days in patients aged 4–11 years, and 100 mg nitazoxanide^ orally twice daily for 3 days in patients aged 1–3 years.
Blastomycosis is considered a rare disease, with most cases occurring in North America. The incidence is higher in males and in individuals with occupational or recreational exposure to wooded or moist environments.
Tinidazole^, paromomycin^, iodoquinol^, and ketoconazole^ have also been used for clearing Blastocystis, as presented in case reports or small series (see references).


^Not FDA-approved for this indication.
==See Also==
* [[Fungal infections]]
* [[Dimorphic fungi]]
* [[Pulmonary infections]]


<!-- Prevention and treatment -->
==External Links==
''Blastomyces dermatitis'' is found in the soil and decaying organic matter like wood or leaves
* [CDC - Blastomycosis](https://www.cdc.gov/fungal/diseases/blastomycosis/index.html)
* [Infectious Disease Society of America - Blastomycosis Guidelines](https://www.idsociety.org/)


<!-- Epidemiology and history -->
{{Infectious diseases}}
Blastomycosis is [[Endemic (epidemiology)|endemic]] to the eastern United States, especially the Ohio and Mississippi River valleys, the Great Lakes, and the St. Lawrence River.  It is also endemic to some parts of Canada, including Quebec, Ontario, and Manitoba.
[[Category:Fungal diseases]]
 
[[Category:Pulmonary diseases]]
== Prognosis ==
[[Category:Infectious diseases]]
Mortality rate in treated cases
[[Category:Rare diseases]]
 
* 0-2% in treated cases among immunocompetent patients
* 29% in immunocompromised patients
* 40% in the subgroup of patients with AIDS
* 68% in patients presenting as [[acute respiratory distress syndrome]] ([[ARDS]])
 
== Epidemiology ==
[[Image:Blasto-map 600.jpg|thumb|Distribution of blastomycosis in North America based on the map given by Kwon-Chung and Bennett,<ref name=kwonchung1992/> with modifications made according to case reports from a series of additional sources.
 
===Urban infections===
There is also a developing profile of urban and other domestic blastomycosis cases, beginning with an outbreak tentatively attributed to construction dust in [[Westmont, Illinois]].
 
<gallery>
File:North American blastomycosis 1.jpg|Granuloma with early suppuration. Fungal organisms difficult to recognize at this low magnification.
File:North American blastomycosis 2.jpg|Large yeast-like fungi seen within giant cells at arrows.
File:North American blastomycosis 3.jpg|Large yeast-like fungi seen within giant cells at arrows.Budding yeasts in cytoplasm of giant cells at arrows. Broad-based budding and double countoured cell wall seen in the giant cell in the center is characteristic of Blastomyces dermatitidis.
</gallery>
 
===Seasonal trends===
Seasonality and weather also appear to be linked to contraction of blastomycosis. Many studies have suggested an association between blastomycosis contraction and cool to moderately warm, moist periods of the spring and autumn.
 
===Gender bias===
Sex is another factor inconstantly linked to contraction of blastomycosis: though many studies show more men than women affected.
 
===Ethnic populations===
Ethnic group or race is frequently investigated in epidemiological studies of blastomycosis, but is potentially profoundly conflicted by differences in residence and in quality and accessibility of medical care, factors that have not been stringently controlled for to date.
 
===Communicability===
There are a very small number of cases of human-to-human transmission of ''B. dermatitidis'' related to dermal contact.
 
==Other animals==
Blastomycosis also affects an indefinitely broad range of mammalian hosts, and dogs in particular are a highly vulnerable sentinel species.
 
== See also ==
* [[Histoplasmosis]]
* [[Paracoccidioidomycosis]]
 
{{Mycoses|state=collapsed}}
 
[[Category:Animal fungal diseases]]
[[Category:Mycosis-related cutaneous conditions]]

Revision as of 12:33, 31 December 2024

Blastomycosis

Blastomycosis
Microscopic image of Blastomyces dermatitidis
ICD-10
ICD-9
DiseasesDB
MedlinePlus
eMedicine
MeSH ID

Overview

Blastomycosis is a fungal infection caused by the dimorphic fungus Blastomyces dermatitidis. It primarily affects the lungs but can disseminate to other parts of the body, including the skin, bones, and central nervous system. The disease is endemic in certain regions of North America, particularly in the Ohio and Mississippi River valleys, the Great Lakes region, and parts of Canada.

Etiology

The causative agent of blastomycosis is Blastomyces dermatitidis, a fungus that exists in two forms: a mold form in the environment and a yeast form in the human body. The fungus is found in moist soil and decaying organic matter, such as wood and leaves.

Pathophysiology

Inhalation of the conidia (spores) of Blastomyces dermatitidis leads to infection. Once inhaled, the spores transform into yeast forms in the alveoli of the lungs. The yeast can evade the immune system and multiply, leading to pulmonary infection. In some cases, the infection can spread hematogenously to other organs.

Clinical Manifestations

The clinical presentation of blastomycosis can vary widely. Common symptoms include:

In cases of disseminated disease, patients may present with skin lesions, osteomyelitis, or meningitis.

Diagnosis

Diagnosis of blastomycosis is based on clinical suspicion, especially in patients with a history of exposure in endemic areas. Diagnostic methods include:

Treatment

The primary treatment for blastomycosis is antifungal therapy. The choice of medication depends on the severity of the disease:

Prognosis

With appropriate treatment, the prognosis for blastomycosis is generally good. However, untreated or severe cases can lead to significant morbidity and mortality.

Prevention

Preventive measures include avoiding activities that disturb soil in endemic areas, especially for immunocompromised individuals. There is currently no vaccine available for blastomycosis.

Epidemiology

Blastomycosis is considered a rare disease, with most cases occurring in North America. The incidence is higher in males and in individuals with occupational or recreational exposure to wooded or moist environments.

See Also

External Links



Infectious diseases
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Viral
Fungal
Parasitic
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