Also called Gilchrist’s disease, blastomycosis is caused by the yeastlike fungus Blastomyces dermatitidis, which usually infects the lungs and produces bronchopneumonia. Less commonly, this fungus may disseminate through the blood and cause osteomyelitis and central nervous system (CNS), skin, and genital disorders.
Untreated blastomycosis is slowly progressive and usually fatal; however, spontaneous remissions occasionally occur. With antifungal therapy and supportive treatment, the prognosis for patients with blastomycosis is good.
Blastomycosis is generally found in North America (where B. dermatitidis normally inhabits the soil) and is endemic to the southeastern United States. Sporadic cases have also been reported in Africa. Blastomycosis usually infects men between ages 30 and 50, but no occupational link has been found. B. dermatitidis is probably inhaled by people who are in close contact with the soil. The incubation period may range from weeks to months.
Initial signs and symptoms of pulmonary blastomycosis mimic those of a viral upper respiratory tract infection. These findings typically include pleuritic chest pain, fever, shaking, chills, night sweats, malaise, anorexia, weight loss, and a dry, hacking, or productive cough (occasionally hemoptysis).
❑ Cutaneous blastomycosis causes small, painless, nonpruritic, and nondistinctive macules or papules on exposed body parts. These lesions become raised and reddened and occasionally progress to draining skin abscesses or fistulas.
❑ Skeletal involvement causes soft-tissue swelling, tenderness, and warmth over bony lesions, which generally occur in the thoracic, lumbar, and sacral regions; long bones of the legs; and, in children, the skull.
❑ Genital involvement produces painful swelling of the testes, the epididymis, or the prostate; deep perineal pain; pyuria; and hematuria.
❑ CNS involvement causes meningitis or cerebral abscesses, resulting in a decreased level of consciousness (LOC), lethargy, and change in mood or affect.
Other dissemination may result in Addison’s disease (adrenal insufficiency), pericarditis, and arthritis.
Various tests may be ordered to diagnose blastomycosis, including:
❑ culture of B. dermatitidis from skin lesions, pus, sputum, or pulmonary secretions
❑ biopsy of tissue from the skin or lungs or of bronchial washings, sputum or pus as appropriate
❑ immunodiffusion testing. This specific study detects antibodies for the A and B antigen of blastomycosis.
In addition, suspected pulmonary blastomycosis requires a chest X-ray, which may show pulmonary infiltrates. Other abnormal laboratory findings include an increased white blood cell count and erythrocyte sedimentation rate, slightly increased serum globulin levels, mild normochromic anemia and, with bone lesions, an increased alkaline phosphatase level.
All forms of blastomycosis respond to I.V. amphotericin B. Therapy is 8 to 10 weeks for skin and noncavitary lung lesions and 10 to 12 weeks for cavitary lesions or infection extending beyond lung and skin. Oral itraconazole may be used as an alternative, especially for monomeningeal blastomycosis patients who can take the drug reliably (6 to 12 months).
❑ If the patient has severe pulmonary blastomycosis, check for hemoptysis. If he’s febrile, provide a cool room, and give tepid sponge baths.
❑ If blastomycosis causes joint pain or swelling, elevate the joint and apply heat.
❑ If the patient has a CNS infection, watch him carefully for decreasing LOC and unequal pupillary response.
❑ If the patient is a man with disseminated disease, watch for hematuria.
Clinical tip Infuse I.V. amphotericin B slowly (a too rapid infusion may cause circulatory collapse). During the infusion, monitor vital signs. (Temperature may rise but should subside within 1 to 2 hours.) Watch for decreased urine output, and monitor laboratory test results for increased blood urea nitrogen and serum creatinine levels and hypokalemia, which may indicate renal toxicity. Immediately report any hearing loss, tinnitus, or dizziness.
❑ To relieve adverse reactions to amphotericin B, give an antiemetic and an antipyretic as needed.
Review other book chapters online related to Blastomycosis:
Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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Title: Handbook of Diseases Authors: Springhouse Publisher: Lippincott Williams & Wilkins Copyright: 2003 ISBN: 1-58255-266-5 
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