Blastomycosis

Blastomycosis is a rare fungus infection caused by the fungus Blastomyces dermatitidis, which grows on wood and soil. It is a common infection among dogs, particularly in areas where it is predominant.

The disease mainly affects the lungs and almost 50% of patients often show minimal or no symptoms. The infection can spread to other parts of the body. The skin is affected more frequently and is involved in approximately 20-40% of cases.

Causes and risk factors.

Infection occurs by inhaling spores that are carried into the air when contaminated soil or wood is disturbed. Humans and animals like dogs, rats, and cats can become infected. The disease is rarely transmitted from human to human or from animal to human. Very rarely, infection can occur through the skin.

Blastomycosis can be found worldwide, but is most common in the south-central and mid-western United States and Canada. the annual incidence in these areas it is around 1-2 cases per 100,000 people. Although people of all ages and sex People with weakened immune systems, such as those with human immunodeficiency virus infection, can become infected (HIV) or organ transplant recipients are at increased risk for serious illness and infection that spreads to other parts of the body.

Symptoms may not be apparent until 3-4 weeks later inhalation of the fungus The average time for symptoms to manifest is 45 days (range 21-106 days).

Clinical features

Patients generally have respiratory symptoms that conform to one of the following specific patterns.

Other symptoms that can occur include bone or joint pain, muscle stiffness and pain, prostate involvement that can cause pain when urinating, and throat compromise that causes hoarseness.

Cutaneous characteristics of blastomycosis

Skin lesions are common on the face, neck, and extremities as the infection spreads from the lungs to other parts of the body. One or many injuries can develop.

• Injuries start as papules, pustules or as subcutaneous nodules.
• In weeks or months the injuries become ulcers and they form crusted sores.
• Over a period of months to years, the lesions enlarge and heal to form raised wart-like scars. Injuries can cover much of the face and cause severe disfigurement.
• Irreversible scars often occur.

Diagnosis

Laboratory and radiological Studies are conducted to confirm the diagnosis of blastomycosis.

• Sputum microscopy and cultures
• Serological tests
• Chest x-ray and Connecticut exploration
• Fabric and leather biopsy

The patient's history is also important in the diagnosis, particularly in areas where there may be an outbreak of disease.

Treatment

Patients with blastomycosis confined to the lungs and without severe symptoms may not require any treatment. Symptoms are usually self-limiting and the infection clears up spontaneously. Treatment should be used if the infection in the lung worsens.

When the infection spreads and the skin is affected, spontaneous resolution does not occur and treatment is necessary.

• Orally administered itraconazole is the drug of choice in mild to moderate disease affecting the lungs or in disease affecting other organs.

• Intravenous amphotericin B is the drug of choice for severe or life-threatening blastomycosis (for example, ARDS, CNS intervention, immunocompromised patients).

Patients with limited skin lesions and relatively mild lung involvement generally make a full recovery. Untreated or more severe disease can lead to severe scarring and disfigurement, or death.