Blastomycosis seems more probable as these young people in Late Woodland and Mississippian times may have been affected because they were spending more time cultivating plants than their Middle Woodland predecessors had done. If true, it would be another severe penalty Late Woodland people had to pay as they shifted to agriculture as a way of life, and it would be a contributing factor to shortening their lifespans compared to those of the Middle Woodland people.Blastomycosis was first described by Thomas Caspar Gilchrist in 1894, as a skin disease. Because of this, blastomycosis is sometimes called "Gilchrists disease". Gilchrist initially identified the cause of the disease as a protozoan, but later correctly identified it as a fungus. In 1898 he and William Royal Stokes published the first description of Blastomyces dermatitidis. Gilchrist referred to the disease as "blastomycetic dermatitis". The systemic spread of blastomycosis was first described in 1902, in a case that had been misdiagnosed as a combination of tuberculosis and a blastomycosis skin infection. In 1907, the dimorphic nature of the Blastomyces fungus was first identified. In 1912, the first case of canine blastomycosis was reported.Prior to the 1930s, blastomycosis was not clearly distinguished from similar fungal conditions. A paper by Rhoda Williams Benham in 1934 distinguished the causative agent of blastomycosis from cryptococcosis and coccidioidomycosis.In the early 1950s, blastomycosis was first determined to be a primarily respiratory disease, with most skin lesions caused by systemic spread from an initial lung infection.
Because the symptoms are variable and nonspecific, blastomycosis is often not even considered in differential diagnosis until antibacterial treatment has failed, unless there are known risk factors or skin lesions. The disease may be misdiagnosed as a carcinoma, leading in some cases to surgical removal of the affected tissue. Upper lung lobes are involved somewhat more frequently than lower lobes. If untreated, many cases progress over a period of months to years to become disseminated blastomycosis. Blastomycosis in the lungs may present a variety of symptoms, or no symptoms at all. If symptoms are present they may range from mild pneumonia resembling a pneumococcal infection to acute respiratory distress syndrome (ARDS). Common symptoms include fever, chills, headache, coughing, difficulty breathing, chest pain, and malaise. Without treatment, cases may progress to chronic pneumonia or ARDS.ARDS is an uncommon but dangerous manifestation of blastomycosis. It was seen in 9 of 72 blastomycosis cases studied in northeast Tennessee. Such cases may follow massive exposure, such during brush clearing operations. In the Tennessee study, the fatality rate was 89% in the ARDS cases, but only 10% in the non-ARDS cases.In disseminated blastomycosis, the large Blastomyces yeast cells translocate from the lungs and are trapped in capillary beds elsewhere in the body, where they cause lesions. The skin is the most common organ affected, being the site of lesions in approximately 60% of cases. The signature image of blastomycosis in textbooks is the indolent, verrucous or ulcerated dermal lesion seen in disseminated disease. Osteomyelitis is also common (12–60% of cases).