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blastomycosis

 
Medical Encyclopedia: Blastomycosis

Definition

Blastomycosis is an infection caused by inhaling microscopic particles (spores) produced by the fungus Blastomyces dermatitidis. Blastomycosis may be limited to the lungs or also involve the skin and bones. In its most severe form, the infection can spread throughout the body and involve many organ systems (systemic).

Description

Blastomycosis is a fungal infection caused by Blastomyces dermatitidis. Although primarily an airborne disease, farmers and gardeners may become infected from contact with spores in the soil through cuts and scrapes. The fungus that causes the disease is found in moist soil and wood in the southeastern United States, the Mississippi River valley, southern Canada, and Central America. Blastomycosis is also called Gilchrist's disease, Chicago disease, or North American blastomycosis. Another South and Central American disease, paracoccidioidomycosis, is sometimes called South American blastomycosis, but despite the similar name, this disease is substantially different from North American blastomycosis. Canine blastomycosis, a common dog disease, is caused by the same fungus that infects humans. However, people do not get this disease from their dogs except only very rarely through dog bites.

Blastomycosis is a rare disease infecting only about 4 in every 100,000 people. It is at least six times more common in men than in women and tends to more often infect children and individuals in the 30–50 year old age group. People who have diabetes mellitus or who are taking drugs that suppress the immune system (immunocompromised) are more likely to develop blastomycosis. Although people with AIDS can get blastomycosis because of their weakened immune system, blastomycosis has not been one of the more common fungal infections associated with AIDS.

— Tish Davidson



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Dictionary: blas·to·my·co·sis   (blăs'tō-mī-kō'sĭs) pronunciation
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n.
A fungal infection caused by a blastomycete and characterized by multiple inflammatory lesions of the skin, mucous membranes, or internal organs.


Dental Dictionary: blastomycosis
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(blas-tō-mī-kō′sis)
n

An infection resulting from the fungus Blastomyces dermatitidis(North American blastomycosis) or Blastomyces brasiliensis(South American blastomycosis); characterized by chronic suppurative lesions. The disseminated form is usually fatal.

Blastomycosis. (Neville/Damm/Allen/Bouquot, 2002, Courtesy of Dr. William Welton)

Blastomycosis. (Neville/Damm/Allen/Bouquot, 2002, Courtesy of Dr. William Welton)

Veterinary Dictionary: blastomycosis
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1. a disseminated or localized infection with Blastomyces spp.
2. infection with any yeastlike organism.

  • cheloidal b. — an unsightly but innocuous disease of bottlenosed dolphins and humans. Characterized by the presence of red, hard, smooth cutaneous nodules. Caused by infection with a fungus, Loboa loboi.
  • cutaneous b. — the skin form of North American blastomycosis.
  • disseminated b. — North American blastomycosis in which lesions are present in most internal parenchymatous organs.
  • equine b. — see epizootic lymphangitis.
  • European b. — see cryptococcosis.
  • keloidal b. — see cheloidal blastomycosis (above).
  • North American b. — infection by Blastomyces dermatitidis which causes primary granulomatous or pyogranulomatous lesions in the lungs. Secondarily, lesions may occur in the skin, eyes, bone and elsewhere. A disease of dogs, cats and humans. Food animals in the same environment are not reported to be affected. Although the disease was originally recorded in North America and is endemic in some areas of the USA, it is now known to occur in Central and South America.
  • South American b. — see paracoccidioidomycosis.
Wikipedia: Blastomycosis
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The term "South American blastomycosis" is sometimes used to describe infection with Paracoccidioides brasiliensis,[1] though the term Paracoccidioidomycosis is more frequently used to describe this condition.
Blastomycosis
Classification and external resources

Blastomyces dermatitidis, the causative agent of blastomycosis.
ICD-10 B40.
ICD-9 116.0
DiseasesDB 1439
MedlinePlus 000102
eMedicine med/231 ped/254
MeSH D001759

Blastomycosis (also known as "North American blastomycosis," "Blastomycetic dermatitis," and "Gilchrist's disease"[2]:319) is a fungal infection caused by the organism Blastomyces dermatitidis. Endemic to portions of North America, blastomycosis causes clinical symptoms similar to histoplasmosis.[3]

Contents

Signs and symptoms

Blastomycosis of skin

Blastomycosis can present in one of the following ways:

  • a flu-like illness with fever, chills, myalgia, headache, and a nonproductive cough which resolves within days.
  • an acute illness resembling bacterial pneumonia, with symptoms of high fever, chills, a productive cough, and pleuritic chest pain.
  • a chronic illness that mimics tuberculosis or lung cancer, with symptoms of low-grade fever, a productive cough, night sweats, and weight loss.
  • a fast, progressive, and severe disease that manifests as ARDS, with fever, shortness of breath, tachypnea, hypoxemia, and diffuse pulmonary infiltrates.
  • skin lesions, usually asymptomatic, appear as ulcerated lesions with small pustules at the margins
  • bone lytic lesions can cause bone or joint pain.
  • prostatitis may be asymptomatic or may cause pain on urinating.
  • laryngeal involvement causes hoarseness.

Cause

Infection occurs by inhalation of the fungus from its natural soil habitat. Once inhaled in the lungs, they multiply and may disseminate through the blood and lymphatics to other organs, including the skin, bone, genitourinary tract, and brain. The incubation period is 30 to 100 days, although infection can be asymptomatic.

Diagnosis

Once suspected, the diagnosis of blastomycosis can usually be confirmed by demonstration of the characteristic broad based budding organisms[4] in sputum or tissues by KOH prep, cytology, or histology. Tissue biopsy of skin or other organs may be required in order to diagnose extra-pulmonary disease. Commercially available urine antigen testing appears to be quite sensitive in suggesting the diagnosis in cases where the organism is not readily detected. While culture of the organism remains the definitive diagnostic standard, its slow growing nature can lead to delays in treatment of up to several weeks.

However, sometimes blood and sputum cultures may not detect blastomycosis; lung biopsy is another option, and results will be shown promptly.

Treatment

Itraconazole given orally is the treatment of choice for most forms of the disease. Ketoconazole may also be used. Cure rates are high, and the treatment over a period of months is usually well tolerated. Amphotericin B is considerably more toxic, and is usually reserved for immunocompromised patients who are critically ill and those with central nervous system disease. Fluconazole has also been tested on patients in Canada.

Prognosis

Mortality rate in treated cases

  • 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

In the United States, blastomycosis is endemic in the Mississippi river and Ohio river basins and around the Great Lakes. The annual incidence is less than 1 case per 100,000 people in Mississippi, Louisiana, Kentucky, and Arkansas. The cases are greater in northern states such as Wisconsin, where from 1986 to 1995 there were 1.4 cases per 100,000 people.[5] It also frequently affects hunting dogs in northern Wisconsin and the upper Mississippi and Wisconsin Rivers.[6]

In Canada, most cases of blastomycosis occur in Northwestern Ontario, particularly around the Kenora area. The moist, acidic soil in the surrounding woodland harbors the fungus.

Blastomycosis is distributed internationally; cases are sometimes reported from Africa.[7]

History

Blastomycosis was first described by Thomas Casper Gilchrist[8] in 1894 and sometimes goes by the eponym Gilchrist's disease.[9] It is also sometimes referred to as Chicago Disease.

See also

References

  1. ^ "South American Blastomycosis: Overview - eMedicine Dermatology". http://emedicine.medscape.com/article/1092860-overview. Retrieved 2009-03-08. 
  2. ^ James, William D.; Berger, Timothy G.; et al. (2006). Andrews' Diseases of the Skin: clinical Dermatology. Saunders Elsevier. ISBN 0-7216-2921-0. 
  3. ^ Ryan KJ; Ray CG (editors) (2004). Sherris Medical Microbiology (4th ed. ed.). McGraw Hill. pp. 676–8. ISBN 0838585299. 
  4. ^ Veligandla SR, Hinrichs SH, Rupp ME, Lien EA, Neff JR, Iwen PC (October 2002). "Delayed diagnosis of osseous blastomycosis in two patients following environmental exposure in nonendemic areas". Am. J. Clin. Pathol. 118 (4): 536–41. doi:10.1309/JEJ0-3N98-C3G8-21DE. PMID 12375640. http://ajcp.metapress.com/openurl.asp?genre=article&issn=0002-9173&volume=118&issue=4&spage=536. 
  5. ^ "Blastomycosis--Wisconsin, 1986-1995". MMWR Morb. Mortal. Wkly. Rep. 45 (28): 601–3. 1996. PMID 8676851. 
  6. ^ Pet Center Blasto in Dogs
  7. ^ Alvarez G, Burns B, Desjardins M, Salahudeen S, AlRashidi F, Cameron D (2006). "Blastomycosis in a young African man presenting with a pleural effusion". Can Respir J 13 (8): 441–4. PMID 17149463. 
  8. ^ "Thomas Caspar Gilchrist (www.whonamedit.com)". http://www.whonamedit.com/doctor.cfm/2763.html. Retrieved 2008-12-10. 
  9. ^ "Gilchrist's disease (www.whonamedit.com)". http://www.whonamedit.com/synd.cfm/3327.html. Retrieved 2008-12-10. 

External links


 
 
Learn More
Blastomyces dermatitidis
Loboa loboi
Blastomycosis: Diagnosis

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