South American Blastomycosis

A progressive mycosis of skin, mucous membranes, lymph nodes, and internal organs caused by Paracoccidioides brasiliensis.

Infections occur only in discrete foci in South and Central America, most often in men aged 20 to 50, especially coffee growers of Colombia, Venezuela, and Brazil. Although a relatively unusual opportunistic infection, paracoccidioidomycosis sometimes occurs in immunocompromised patients, including those with AIDS.

Although specific natural sites for P. brasiliensis remain undefined, it is presumed to exist in soil as a mold, with infections thought to follow inhalation of conidia (spores). These convert into invasive yeasts within the lungs at 37 degrees C (98.6 degrees F) and are assumed to spread to other sites hematogenously and via lymphatics.

Symptoms and Signs

Mucocutaneous infections most often involve the face, especially at the nasal and oral mucocutaneous borders. Yeasts are usually abundantly present within pinpoint lesions throughout granular bases of slowly expanding ulcers. Regional lymph nodes enlarge, become necrotic, and discharge necrotic material through the skin. Lymphatic infections mainly involve painless enlargement of cervical, supraclavicular, or axillary nodes. Visceral infections are characterized by focal lesions causing enlargement mainly of the liver, spleen, and abdominal lymph nodes, sometimes with accompanying abdominal pain. Mixed infections involve combinations of all three patterns.

Diagnosis, Prognosis, and Treatment

Culture is diagnostic, although the presence in specimens of large (often > 15 ?m) yeasts forming characteristic multiple buds provides strong presumptive evidence.

Clinically apparent infections are generally chronic and progressive but not usually fatal. Azoles are highly effective. Oral itraconazole is generally considered the drug of choice. IV amphotericin B also can eliminate the infection and is often used in very severe cases. Sulfonamides, which are widely used in some countries because they are inexpensive, can suppress growth and improve lesions but are not curative.

Author: Carolyn Willbanks