Blastomycosis is a rare fungal infection caused by inhaling a
fungus (Blastomyces dermatitidis), which is found in wood and soil.
Blastomycosis occurs most often in people living in the
south-central and Midwestern US and Canada. Exposure to soil is the key risk factor. The
disease usually affects people with compromised immune systems, such as people with HIV or
organ transplant recipients.
Men are more likely to be affected than women. Lung infection may produce no symptoms,
but when the infection is widespread, skin lesions or bone lesions may appear and the
urogenital system (bladder, kidney, prostate, testes) may be affected.
The incidence of blastomycosis is 1-2 out of every 100,000 people in geographic areas
where blastomycosis occurs most frequently. It is even less common outside those areas
Information about Blastomycosis
Blastomycosis is a fungal infection caused by Blastomyces dermatitidis. Although
primarily an airborne disease, farmers and gardeners may become infected from contact with
spores in the soil through cuts and scrapes. The fungus that causes the disease is found
in moist soil and wood in the southeastern United States, the Mississippi River valley,
southern Canada, and Central America. Blastomycosis is also called Gilchrist's disease,
Chicago disease, or North American blastomycosis. Another South and Central American
disease, paracoccidioidomycosis, is sometimes called South American blastomycosis, but
despite the similar name, this disease is substantially different from North American
blastomycosis. Canine blastomycosis, a common dog disease, is caused by the same fungus
that infects humans. However, people do not get this disease from their dogs except only
very rarely through dog bites.
Blastomycosis is a rare disease infecting only about 4 in every 100,000 people. It is
at least six times more common in men than in women and tends to more often infect
children and individuals in the 30-50 year old age group. People who have diabetes
mellitus or who are taking drugs that suppress the immune system (immunocompromised) are
more likely to develop blastomycosis. Although people with AIDS can get blastomycosis
because of their weakened immune system, blastomycosis has not been one of the more common
fungal infections associated with AIDS.
Causes & symptoms of Blastomycosis
Once inhaled, the spores of B. dermatitidis can lodge in the lungs and cause a
localized inflammation. This is known as primary pulmonary blastomycosis. The disease does
not spread from one person to another. In the early stages, symptoms may include a dry
cough, fever, heavy sweating, fatigue, and a general feeling of ill health. In
approximately 25% of blastomycosis cases, only the lungs are affected. As the disease
progresses, small lesions form in the lungs causing the air sacs deep within the lungs
(alveoli) to break down and form small cavities.
In another 35%, the disease involves both the lungs and the skin. Bumps develop on the
skin, gradually becoming small, white, crusted blisters filled with pus. The blisters
break open, creating abscesses that do not heal. Approximately 19% of infected people have
skin sores without infection in the lungs.
The remaining approximately 20% of the infected population has blastomycosis that has
spread or disseminated to other systems of the body. Symptoms may include pain and lesions
on one or more bones, the male genitalia, and/or parts of the central nervous system. The
liver, spleen, lymph nodes, heart, adrenal glands, and digestive system may also be
A positive diagnosis of blastomycosis is made when the fungus B. dermatitidis is
identified by direct microscopic examination of body fluids such as sputum and prostate
fluid or in tissue samples (biopsies) from the lung or skin . Another way to diagnose
blastomycosis is to culture and isolate the fungus from a sample of sputum. Chest x rays
are used to assess lung damage, but alone cannot lead to a definitive diagnosis of
blastomycosis because any damage caused by other diseases, such as by pneumonia or
tuberculosis, may appear look on the x ray. Because its symptoms vary widely,
blastomycosis is often misdiagnosed.
Blastomycosis must be treated or it will gradually lead to death. Treatment with the
fungicidal drug ketoconazole (Nizoral) taken orally is effective in about 75% of patients.
Amphotericin B (Fungizone) given intravenously is also very effective, but it has more
toxic side effects than ketoconazole. Treatment with amphotericin B usually requires
hospitalization, and the patient may also receive other drugs to minimize the its side
Alternative treatment for Blastomycosis
Alternative treatment for fungal infections focuses on creating an internal environment
where the fungus cannot survive. This is accomplished by eating a diet low in dairy
products, sugars, including honey and fruit juice, and foods like beer that contain yeast.
This is complemented by a diet consisting, in large part, of uncooked and unprocessed
foods. Supplements of vitamins C, E, A-plus, and B complex may also be useful. Lactobacillus
acidophilus and Bifidobacterium will replenish the good bacteria in the
intestines. Some antifungal herbs, like garlic (Allium sativum), can be consumed in
relatively large doses and for an extended period of time in order to increase
effectiveness. A variety of antifungal herbs, such as myrrh (Commiphora molmol),
tea tree oil (Melaleuca spp.), citrus seed extract, pau d'arco tea (Tabebuia
impetiginosa), and garlic may also be applied directly to the infected skin.
Prognosis of Blastomycosis
Left untreated, blastomycosis gradually leads to death. When treated, however, patients
begin to improve within one week and, with intensive treatment, may be cured within
several weeks. The highest rate of recovery is among patients who only have skin lesions.
People with the disseminated form of the disease are least likely to be cured and and most
likely to suffer a relapse.
Prevention of Blastomycosis
Because the fungus that causes blastomycosis is airborne and microscopic, the only form
of prevention is to avoid visiting areas where it is found in the soil. For many people
this is impractical. Since the disease is rare, people who maintain general good health do
not need to worry much about infection.