Blastomycosis

https://doi.org/10.1016/j.idc.2015.10.002Get rights and content

Section snippets

Key points

  • Blastomyces dermatitidis is endemic to the shore of lakes and rivers in Central and Southern North America.

  • Infection can occur in any host but is more severe in immunocompromised patients.

  • Acute respiratory distress syndrome and central nervous system involvement are the two most serious complications of blastomycosis.

  • Early diagnosis of blastomycosis can be made by demonstrating distinctive yeast forms in tissue biopsy and by antigen detection using enzyme immunoassay techniques.

  • Mild to moderate

Epidemiology

Blastomycosis is seen most frequently in the Mississippi and Ohio River valleys, Midwestern states and Canadian provinces that border the Great Lakes, and areas adjacent to the Saint Lawrence Seaway1, 7, 8, 9, 10, 11, 12, 13, 14 (Fig. 1). However, occasional cases have been reported from Florida, Colorado, Hawaii, Israel, India, Africa, and Central and South America.2, 15, 16 Within areas known to be endemic for blastomycosis, the disease occurs in certain areas much more frequently than in

Pathogenesis

B dermatitidis is a thermally dimorphic fungus that grows as a mold in the environment, as yeast in tissues, and at 35°C to 37°C in the laboratory. The environmental mold phase is typically observed in the laboratory at 25°C as white colonies that slowly turn a light brown color. The colonies consist of branching septate hyphae that produce conidia. Yeast cells are 8 to 20 μm in diameter and are characterized by a doubly thick, refractile cell wall and broad-based budding, with the daughter

Clinical manifestations

Blastomycosis causes a spectrum of illness in regard to severity and organ involvement, ranging from asymptomatic subclinical infection to widespread disseminated infection and, less commonly, fulminant pulmonary infection with ARDS. Most infected patients remain asymptomatic.26 Blastomycosis most often involves the lungs, and symptoms appear after an incubation period of 2 to 6 weeks.2, 26 Disseminated, extrapulmonary infection can affect nearly every organ but most commonly involves the skin,

Immunocompromised Patients

Blastomycosis is described in patients with human immunodeficiency virus (HIV)/AIDS, solid organ and hematopoietic cell transplant recipients, and patients who have been treated with immunosuppressive medications, including glucocorticoids, cytotoxic agents, and tumor necrosis factor (TNF)-alpha inhibitors. In one large series, only 2.7% of patients seen before 1978 were immunocompromised compared with 23.6% between 1978 and 1991.38 Subsequent reports focused on specific populations, such as

Diagnosis

The diagnosis of blastomycosis is often delayed because of a low index of suspicion. In Mississippi, a state that has a high incidence of blastomycosis, pulmonary blastomycosis was correctly diagnosed at initial presentation only 5% of the time in one study.12 If patients had both pulmonary symptoms and cutaneous lesions, the diagnosis rate increased to 64%. In nearly half of the patients, the diagnosis was made more than 30 days into their illness.12 A thorough history that includes travel to

Treatment

The Infectious Diseases Society of America’s guidelines for the treatment of blastomycosis emphasize that all patients with blastomycosis should receive antifungal therapy regardless of the clinical presentation because of the high likelihood of progression or recurrence of the infection if not treated.57 The treatment of pulmonary and disseminated blastomycosis is determined by the severity of the disease, the presence of CNS involvement, and the host immune status.

Outcomes

Overall mortality associated with blastomycosis is reported to be 4% to 6%.3 Mortality rates as high as 18% have been reported in patients with CNS blastomycosis and as high as 89% in patients with ARDS.13, 37, 65 Immunocompromising conditions, such as AIDS and solid organ transplantation, were associated with mortality rates as high as 25% to 41% in several earlier series.37, 38, 39, 40, 41 However, more recent case series report mortality rates of 45% in patients with ARDS and no deaths from

First page preview

First page preview
Click to open first page preview

References (74)

  • S.R. Day et al.

    Successful treatment of osseous blastomycosis without pulmonary or disseminated disease and review of the literature

    Diagn Microbiol Infect Dis

    (2014)
  • T. Lahm et al.

    Corticosteroids for blastomycosis-induced ARDS: a report of two patients and review of the literature

    Chest

    (2008)
  • G.J. Pearson et al.

    Case report: treatment of blastomycosis with fluconazole

    Am J Med Sci

    (1992)
  • M. Saccente et al.

    Clinical and laboratory update on blastomycosis

    Clin Microbiol Rev

    (2010)
  • J.A. Smith et al.

    Blastomycosis

    Proc Am Thorac Soc

    (2010)
  • J.A. Smith et al.

    New developments in blastomycosis

    Semin Respir Crit Care Med

    (2015)
  • A. Freifeld et al.

    Voriconazole use for endemic fungal infections

    Antimicrob Agents Chemother

    (2009)
  • B.S. Klein et al.

    Two outbreaks of blastomycosis along rivers in Wisconsin. Isolation of Blastomyces dermatitidis from riverbank soil and evidence of its transmission along waterways

    Am Rev Respir Dis

    (1987)
  • D.J. Baumgardner et al.

    Epidemiology of blastomycosis in a region of high endemicity in north central Wisconsin

    Clin Infect Dis

    (1992)
  • M.S. Dworkin et al.

    The epidemiology of blastomycosis in Illinois and factors associated with death

    Clin Infect Dis

    (2005)
  • M.V. Cano et al.

    Blastomycosis in Missouri: epidemiology and risk factors for endemic disease

    Epidemiol Infect

    (2003)
  • T.L. Crampton et al.

    Epidemiology and clinical spectrum of blastomycosis diagnosed at Manitoba hospitals

    Clin Infect Dis

    (2002)
  • S.W. Chapman et al.

    Endemic blastomycosis in Mississippi: epidemiological and clinical studies

    Semin Respir Infect

    (1997)
  • M.A. De Groote et al.

    Expanding epidemiology of blastomycosis: clinical features and investigation of 2 cases in Colorado

    Clin Infect Dis

    (2000)
  • H.S. Randhawa et al.

    Blastomycosis in India: report of an imported case and current status

    Med Mycol

    (2013)
  • M. Roy et al.

    A large community outbreak of blastomycosis in Wisconsin with geographic and ethnic clustering

    Clin Infect Dis

    (2013)
  • J.L. Anderson et al.

    Canine blastomycosis in Wisconsin: a survey of small-animal veterinary practices

    Med Mycol

    (2014)
  • J.A. Smith et al.

    Cutaneous manifestations of endemic mycoses

    Curr Infect Dis Rep

    (2013)
  • A. Koneti et al.

    Evasion of innate immune responses: evidence for mannose binding lectin inhibition of tumor necrosis factor alpha production by macrophages in response to Blastomyces dermatitidis

    Infect Immun

    (2008)
  • G. Girouard et al.

    Observations on (1-3)-beta-D-glucan detection as a diagnostic tool in endemic mycosis caused by Histoplasma or Blastomyces

    J Med Microbiol

    (2007)
  • C.A. Kauffman et al.

    Endemic fungal infections in solid organ and hematopoietic cell transplant recipients enrolled in the Transplant-Associated Infection Surveillance Network (TRANSNET)

    Transpl Infect Dis

    (2014)
  • R.W. Bradsher et al.

    Blastomycosis

  • M. Wuthrich et al.

    Vaccine-induced protection against 3 systemic mycoses endemic to North America requires Th17 cells in mice

    J Clin Invest

    (2011)
  • R.W. Bradsher et al.

    Growth inhibition of Blastomyces dermatitidis in alveolar and peripheral macrophages from patients with blastomycosis

    Am Rev Respir Dis

    (1987)
  • B.S. Klein et al.

    Isolation of Blastomyces dermatitidis in soil associated with a large outbreak of blastomycosis in Wisconsin

    N Engl J Med

    (1986)
  • R.W. Bradsher

    Histoplasmosis and blastomycosis

    Clin Infect Dis

    (1996)
  • P.G. Pappas

    Blastomycosis

    Semin Respir Crit Care Med

    (2004)
  • Cited by (102)

    • Mechanism of action of antifungal agents

      2023, How Synthetic Drugs Work: Insights into Molecular Pharmacology of Classic and New Pharmaceuticals
    • A Pseudotumor

      2022, American Journal of Medicine
    View all citing articles on Scopus

    All authors declare that they have no financial or commercial conflicts of interest.

    View full text