Blastomycosis

Blastomycosis is a fungal infection caused by inhaling Blastomyces dermatitidis spores. If it involves only the lungs, it is called pulmonary blastomycosis. Only about half of people with the disease have symptoms, which can include fever, cough, night sweats, muscle pains, weight loss, chest pain, and feeling tired. These symptoms usually develop between three weeks and three months after breathing in the spores. In those with weak immune systems, the disease can spread to other areas of the body, including the skin and bones. Budding yeasts in cytoplasm of giant cells at arrows. Broad-based budding and double countoured cell wall seen in the giant cell in the center is characteristic of Blastomyces dermatiditis.Granuloma with early suppuration. Fungal organisms difficult to recognize at this low magnification.Large yeast-like fungi seen within giant cells at arrows.Nodular skin lesions of blastomycosis, one of which is a bullous lesion on top of a nodule. Blastomycosis is a fungal infection caused by inhaling Blastomyces dermatitidis spores. If it involves only the lungs, it is called pulmonary blastomycosis. Only about half of people with the disease have symptoms, which can include fever, cough, night sweats, muscle pains, weight loss, chest pain, and feeling tired. These symptoms usually develop between three weeks and three months after breathing in the spores. In those with weak immune systems, the disease can spread to other areas of the body, including the skin and bones. Blastomyces dermatitis is found in the soil and decaying organic matter like wood or leaves. Participating in outdoor activities like hunting or camping in wooded areas increases the risk of developing blastomycosis. There is no vaccine, but the disease can be prevented by not disturbing the soil. Treatment is with itraconazole for mild or moderate disease and amphotericin B for severe disease. With both, the duration of treatment is 6-12 months. Overall, 4-6% of people who develop blastomycosis die; however, if the central nervous system is involved, this rises to 18%. People with AIDS or on medications that suppress the immune system have the highest risk of death at 25-40%. Blastomycosis is endemic to the eastern United States, especially the Ohio and Mississippi River valleys, the Great Lakes, and the St. Lawrence River. It is also endemic to some parts of Canada, including Quebec, Ontario, and Manitoba. In these areas, there are about 1 to 2 cases per 100,000 per year. Blastomycosis was first described by Thomas Casper Gilchrist in 1894; because of this, it is sometimes called 'Gilchrist's disease'. The severity of symptoms depends on a person's immune status; less than 50% of healthy people with blastomycosis have symptoms, while immunocompromised patients can have the disease spread beyond the lungs to other organs like the skin and bones.