Disease/Syndrome

Blastomycosis

Category

Infection, Occupational

Acute/Chronic

Subacute

Synonyms

Blastomyces dermatitidis infection; North American blastomycosis;

Comments

INITIAL SYMPTOMS: Acute blastomycosis is a self-limited, flu-like illness with cough and fever; Consider blastomycosis for patients in endemic areas with pneumonia or new skin lesions. [5MCC-2015] Usually a chronic lung infection; [ABX Guide] FINDINGS: Acutely, blastomycosis presents as an upper respiratory infection, and the diagnosis is often not suspected or made. Acute disease usually resolves in 1-3 weeks. In the chronic form, lesions may develop in the skin, lungs, bone, prostate, and epididymis. Skin lesions (usually on face or extremities) include papules, verrucous growths, and ulcerations. [CCDM, p. 69-70] Hematogenous spread to skin, bones, and prostate/epididymis is common. [Harrison ID, p. 1079-80] Acute form mimics pneumonia or influenza. Chronic form mimics tuberculosis and cancer. Skin disease mimics skin cancer and keratoacanthoma. [Harrison ID, p. 1080] Acute infections usually present as a flu-like illness with a dry cough or pleuritic chest pain without other systemic symptoms. The most common findings on chest x-ray are diffuse infiltrates or segmental consolidation. CNS infections with meningitis and mass lesions of the brain have been reported. [ID, p. 2252] About 50% of cases are asymptomatic. Infection is localized to the lungs in 70-80% of cases. The common presentations are pulmonary, cutaneous, and systemic. Pulmonary findings may include pleural effusions, cavitary lesions, nodular infiltrates, mass lesions, respiratory failure, and rarely hilar adenopathy. [5MCC-2015] Increased WBC count and mild normocytic anemia are seen. [Wallach, p. 571] Not common are hilar/mediastinal lymphadenopathy and pleural effusions. [Cecil, p. 1981] SYNDROMES: Chronic disease may resemble tuberculosis with cavitary lung disease, dissemination, weight loss, night sweats, productive cough, and pleuritic chest pain. B. dermatitidis is one of the causes of Parinaud's oculoglandular syndrome. [Guerrant, p. 576, 1005] Pneumonia is the most common presentation, followed by skin lesions (verrucous and ulcerative), and infections of the bone, genitourinary system, nervous system, and eye. Abscesses can occur in the skin, subcutaneous tissue, brain, bone, prostate, and other organs (myocardium, pericardium, orbit, sinuses, pituitary, and adrenal). [PPID, p. 2963-73] CNS disease (meningitis and brain abscess) has been reported in about 40% of AIDS patients infected with blastomycosis. [Harrison ID, p. 1080] EPIDEMIOLOGY: Risk factors include exposure to moist soil in woodlands or near waterways. [CCDM, p. 70] Most cases are manual laborers, hunters, or farmers. [ABX Guide] Pulmonary infection occurs after inhalation of conidia. Infection by inoculation is rare. Immunocompromised patients have more severe disease--after either a new infection or reactivation of an old infection.[Cecil, p. 1981]

Latency/Incubation

Weeks to months; median of 1.5 months; [CCDM]

Diagnostic

Wet mount or KOH prep (large yeast with broad-based bud); Tissue stains; Culture delays diagnosis because of slow growth; Serology not usually useful; Urine assay for antigen 90% sens & 99% spec but histoplasmosis cross reacts; [ABX Guide]

ICD-9 Code

116.0

Effective Antimicrobics

Yes

Reference Link

Merck Manual: Blastomycosis

Related Information in Haz-Map
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Job Tasks

High risk job tasks associated with this disease:

Agents

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