Sporotrichosis - Causes, Symptoms and Treatments

Sporotrichosis is a chronic disease caused by the fungus Sporothrix schenckii. It occurs in three forms: cutaneous lymphatic, which produces nodular erythematous primary lesions and secondary lesions along lymphatic channels; pulmonary, a rare form that produces a productive cough and pulmonary lesions; and disseminated, another rare form that may cause arthritis or osteomyelitis. The course of sporotrichosis is slow, the prognosis is good, and fatalities are rare. However, untreated skin lesions may cause secondary bacterial infection.

Causes of Sporotrichosis:

S. schenckii is found in soil, wood, sphagnum moss, and decaying vegetation throughout the world. Because this fungus usually enters through broken skin (the pulmonary form through inhalation), sporotrichosis is more common in horticulturists, agricultural workers, and home gardeners. Perhaps because of occupational exposure, it's more prevalent in adult men than in women and children.

Signs and symptoms of Sporotrichosis:

After an incubation period that lasts from 1 week to 3 months, cutaneous lymphatic sporotrichosis produces characteristic skin lesions, usually on the hands or fingers. Each lesion begins as a small, painless, movable subcutaneous nodule, but grows progressively larger, discolors, and eventually ulcerates. Later, additional lesions form along the adjacent lymph node chain.

Pulmonary sporotrichosis causes a productive cough, lung cavities and nodules, hilar adenopathy, pleural effusion, fibrosis, and the formation of a fungus ball. It's often associated with sarcoidosis and tuberculosis.

Disseminated sporotrichosis produces multifold lesions that spread from the primary lesion in the skin or lungs. The disease begins insidiously, typically causing weight loss, anorexia, synovial or bony lesions and, possibly, arthritis or osteomyelitis.

Diagnosis of Sporotrichosis:

Typical clinical findings and a culture of S. schenckii in sputum, pus, or bone drainage confirm this diagnosis.

Histologic identification is difficult. Diagnosis must rule out tuberculosis, sarcoidosis and, in patients with the disseminated form, bacterial osteomyelitis and neoplasm.

Treatment of Sporotrichosis:

Sporotrichosis doesn't require isolation. The cutaneous lymphatic form usually responds to application of a saturated solution of potassium iodide, generally continued for 1 to 2 months after lesions heal. Occasionally, cutaneous lesions must be excised or drained. The disseminated form responds to itraconazole but may require several weeks of treatment. Local heat application relieves pain. Cavitary pulmonary lesions may require surgery.

Special considerations of Sporotrichosis:

1. Keep lesions clean, make the patient as comfortable as possible, and carefully dispose of contaminated dressings.

2. Warn patients about possible adverse effects of drugs. Because amphotericin B may cause fever, chills, nausea, and vomiting, give antipyretics and antiemetics, as ordered.

3. To help prevent sporotrichosis, advise horticulturists and home gardeners to wear gloves while working.