Short answer · Medically reviewed summary · Last updated: 2026-05-08
Blastomycosis was first described in 1894 by Dr. Thomas Caspar Gilchrist, who identified the fungal pathogen Blastomyces dermatitidis in a patient with a chronic skin lesion.
1 people with Blastomycosis have shared their first-person experience on this question at DiseaseMaps.
What is the history of Blastomycosis?
History of Blastomycosis: when and how it was discovered, and the milestones in research since, medically reviewed.
Blastomycosis was first described in 1894 by Dr. Thomas Caspar Gilchrist, who identified the fungal pathogen Blastomyces dermatitidis in a patient with a chronic skin lesion. Historically known as "Gilchrist’s disease," our understanding of Blastomycosis has evolved from a rare, misunderstood dermatological condition to a recognized systemic infection caused by inhaling fungal spores found in moist soil and decaying organic matter.
Who first discovered Blastomycosis?
In 1894, Dr. Thomas Caspar Gilchrist presented the first case of Blastomycosis to the American Dermatological Association. Initially, it was believed to be a protozoan infection. It wasn't until later studies confirmed the causative agent as the dimorphic fungus Blastomyces dermatitidis. For decades, the disease was often misdiagnosed as tuberculosis or skin cancer due to the similarity of pulmonary lesions and skin ulcers.
How has the treatment of Blastomycosis evolved?
Before the mid-20th century, Blastomycosis was frequently fatal or required disfiguring surgeries. The landscape changed dramatically with the introduction of antifungal therapies, which transformed the prognosis for patients significantly:
- 1950s: The introduction of Amphotericin B provided the first effective systemic treatment.
- 1980s: The development of azole antifungals, such as ketoconazole and later itraconazole, allowed for oral outpatient management.
- Modern Era: Current clinical standards rely on lipid-based formulations of Amphotericin B for severe cases, followed by months of itraconazole therapy.
How has our understanding of Blastomycosis changed?
Modern medical technology, including advanced PCR testing and molecular diagnostics, has drastically improved the speed of identifying Blastomycosis. While genetics do not cause the disease, research now explores why some individuals develop severe systemic Blastomycosis while others remain asymptomatic after exposure. Today, the 27 members of the DiseaseMaps community with Blastomycosis highlight the importance of early awareness, as the disease remains endemic in parts of North America, particularly the Ohio and Mississippi River valleys.
Next steps
- Consult an infectious disease specialist if you have persistent respiratory symptoms after visiting endemic areas.
- Join the Blastomycosis community on DiseaseMaps.org to share experiences with others.
- Review updated clinical guidelines from the Infectious Diseases Society of America (IDSA).
Medical disclaimer: This content is for informational purposes only and does not constitute professional medical advice, diagnosis, or treatment.
References
- NIH Genetic and Rare Diseases Information Center (GARD): Blastomycosis overview.
- Centers for Disease Control and Prevention (CDC): Fungal Diseases - Blastomycosis.
- Infectious Diseases Society of America (IDSA): Clinical Practice Guidelines for the Management of Blastomycosis.
- PubMed: Historical perspectives on the discovery of Blastomyces dermatitidis.
· Blastomycosis
· North American Blastomycosis
· Gilchrist’s Disease
· Chicago Disease
History
Blastomycosis was discovered by a French botanist/biologist named Philippe Edouard Léon Van Tieghem in 1876. Blastomycosis is often called Gilchrist’s Disease because it was first described by Thomas Caspar Gilchrist who initially named it b. dermatitidis thinking that it was primarily a dermatological disease. Although further studies showed that the pulmonary system was the first organ system to be affected (1).
Etiological Agents
Blastomyces dermatitidis, the asexual state of Ajellomyces dermatitidis, which is one of the two serotypes (5).
Reservoirs
Moist soil that has decomposing organic debris. You would find these type of soils mostly in south central, south eastern and mid western United states. Microfoci can also be found in Central and South America, and Africa (4).
Transmission
· Blastomycosis is contracted by inhaling aerosolized conidial forms of b. dermatitidis particles found in moist soil, where there is rotting vegetation that has been disturbed (2).
· In rare cases blastomycosis may be transmitted by extrapulmonary manifestations, the skin, which may have lesions that can be contagious (2). Other organs may be affected but skin is the most common besides the lungs.
· Some animals are susceptible to acquiring Blastomycosis also, especially dogs.
General Characteristics
B. dermatitidis is a thermal acting (changing form when the temperature is changed) dimorphic fungus
· When in cooler temperatures (25⁰C) the fungus is a mycelia, mould like form which is infectious.
· When in warmer temperatures (37⁰C) like in the body, the fungus transforms into a yeast once present in the body. The life cycle ends once it is in the body.
- Taxanomic info (6):
· Kingdom: Fungi
· Phylum: Ascomycota
· Class: Euascomycetes
· Order: Onygenales
· Family: Onygenaceae
· Genus: Blastomyces
Tests for Identification
Chest X-ray- In a patient who is positive for blastomycosis you will see alveolar infiltrates, tumor like densities, and nodules in order of frequency (2).
Sputum microscopy
- a small sample of freshly expelled sputum is placed on a microscope slide and 10 % of potassium hydroxide is added. Place a microscope cover slip on top of your specimen and examine it under a microscope. Upon examination you will find yeasts, 8-20 micrometers in size, with single broad based yeast buds. Double refractile walls and multiple nuclei cells will also be present (2).
- Sputum culture- Sabouraud dextrose agar is the media use to isolate and get absolute confirmation for a diagnosis of b. dermatitidis.The down side to this method is the time it takes to see culture growth can be as little as 5 days or sometimes as many as 30 days (2).
Serological tests
- Enzyme Immunoassay (EIA)- is the easiest to perform and the antibodies/antigens are detected early (9).
- Complement fixation and immunodiffusion test- both tests lack sensitivity so they cannot be used to exclude a blastomycosis diagnosis (2)
Posted May 22, 2017 by Mollysmission 2000
