Blastomycosis

Blastomycosis is a primary systemic mycosis caused by the fungus Blastomyces dermatitidis that produces a systemic fungal infection ^[1][4]. It is a fungal infection typically involving the lungs and capable of spreading to the brain, stomach, intestine, and skin ^[1].

Approximately half of those infected develop symptoms such as fever, cough, night sweats, muscle pain, weight loss, chest pain, and fatigue, with onset usually three weeks to three months after spore inhalation ^[1]. Pulmonary involvement occurs in about 79% of cases, and dissemination to skin, bones, or the central nervous system affects 25% to 40% of patients ^[1]. Cutaneous disease may present as crusting purplish warty plaques with a raised bumpy border and central depression ^[1].

Blastomycosis is endemic to the eastern United States and Canada, particularly the Ohio and Mississippi River valleys, the Great Lakes, and the St. Lawrence region ^[1]. The broader group of endemic mycoses, including blastomycosis, is a leading cause of morbidity and mortality globally, with burden rising yearly ^[2]. In the United States, some studies report disproportionately high incidence or mortality among Black people, while in Canada certain First Nations groups may show elevated incidence, though confounding by residence and care access is possible ^[1]. Increasing reports from previously non-endemic areas have been attributed to factors such as travel, climate change, and improved diagnostics ^[3].

The causative fungus resides in soil and decaying organic matter such as wood and leaves, and humans acquire infection by inhaling its spores ^[1]. Outdoor activities like hunting or camping in wooded areas raise exposure risk ^[1].

No vaccine exists for blastomycosis, but disturbance of soil containing the fungus should be avoided to lower exposure risk ^[1]. Persons engaging in outdoor recreation in wooded endemic areas should take care not to disrupt potentially contaminated soil or decaying vegetation ^[1].

1. 1 Wikipedia contributors. Blastomycosis - Wikipedia [Internet]. Wikipedia. cited 12 Aug 2026. Available from: https://en.wikipedia.org/wiki/Blastomycosis
2. 2 Thompson GR 3rd et al. Global guideline for the diagnosis and management of the endemic mycoses: an initiative of the European Confederation of Medical Mycology in cooperation with the International Society for Human and Animal Mycology. Lancet Infect Dis. 2021 Dec. PMID: 34364529. doi: 10.1016/S1473-3099(21)00191-2. PubMed: https://pubmed.ncbi.nlm.nih.gov/34364529/
3. 3 Ashraf N et al. Re-drawing the Maps for Endemic Mycoses. Mycopathologia. 2020 Oct. PMID: 32040709. doi: 10.1007/s11046-020-00431-2. PubMed: https://pubmed.ncbi.nlm.nih.gov/32040709/
4. 4 Wikidata contributors. blastomycosis [Internet]. Wikidata. cited 23 Oct 2026. Available from: https://www.wikidata.org/wiki/Q627368