Blastomycosis

CASES/YEAR
3,000 (US); 60,000 (Global)
CATEGORY
Sapronoses
AGENT TYPE
Fungi (Endemic-Dimorphic)
OTHER NAMES
Blastomyces dermatitidis infection; North American blastomycosis;
ACUITY
Subacute/Chronic
INCUBATION
Weeks to months; median of 1.5 months; [CCDM]
INITIAL SYMPTOMS
"In the immunocompetent host, acute pulmonary blastomycosis can be mild and self-limited and may not require treatment." [5MCC-2020] Pulmonary infections in 70-75% of cases; [ABX Guide]
PRECAUTIONS
Standard; "Not transmitted from person to person." [CDC 2007 Guideline for Isolation Precautions]
COMMENTS
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. 1005] Acute form mimics pneumonia or influenza. Chronic form mimics tuberculosis and cancer. Skin disease mimics skin cancer and keratoacanthoma. [Harrison ID, p. 1004] 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-2020] Increased WBC count and mild normocytic anemia are seen. [Wallach, p. 1160] Not common are hilar/mediastinal lymphadenopathy and pleural effusions. [Cecil, p. 2040]

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. 3181-4] CNS disease (meningitis and brain abscess) has been reported in about 40% of AIDS patients infected with blastomycosis. [Harrison ID, p. 1005]

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. 2039-40]
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]
SCOPE
Most cases reported in N. America; [Harrison ID] USA & Canada bordering Mississippi, Ohio, & St. Lawrence Rivers & Great Lakes; Also in parts of Africa, India, Middle East, Central & S. America; [CCDM]
SIGNS & SYMPTOMS
  • >arthralgia
  • >fatigue, weakness
  • >fever
  • >myalgia
  • E nasal ulcers
  • E stomatitis
  • H anemia
  • H leukocytosis
  • H lymphadenopathy
  • N headache
  • O conjunctivitis, acute
  • O oculoglandular syndrome
  • R chest pain
  • R cough
  • R dyspnea
  • R hemoptysis
  • R sputum production
  • S papules or plaques
  • S pustule
  • S skin or subcutaneous nodule
  • S ulcer of skin
  • S warty growth of the skin
  • X cystic or cavitary lesions
  • X hilar lymphadenopathy
  • X lung infiltrates
  • X pleural effusions
  • *ARDS
  • *arthritis
  • *brain abscess or lesion
  • *epididymo-orchitis
  • *erythema nodosum
  • *mediastinitis
  • *meningitis
  • *myelitis
  • *myocarditis
  • *osteomyelitis
  • *pericarditis
  • *pneumonia
  • *uveitis
  • *weight loss
ANTIMICROBIC

Yes

VACCINE

No

ENTRY
Inhalation, Skin or Mucous Membranes (Includes Conjunctiva)
SOURCE
Soil or Dust (Ingesting or Inhaling)
RESERVOIR
RISK FACTORS
  • AIDS patients
  • Cancer patients
  • Plow or excavate soil in endemic area
  • Travel to endemic area
  • Victim--air release of infectious agents
REFERENCES FOR CASES/YEAR
1. (US) Annual incidence of 0.3-1.8 cases/100,000; [Gorbach, p. 94] Calculate: If assume 1 case per 100,000, then 3000 cases for a population of 300 million (US);
2. (Global) 20 X US cases/yr;