inconstantly linked to contraction of blastomycosis: though many studies show more men than women affected, some show no sex-related bias. As mentioned above, most cases are in middle aged adults, but all age groups are affected, and cases in children are not uncommon. Ethnic populations Ethnic group or race is frequently investigated in epidemiological studies of blastomycosis, but is potentially confounded by differences in residence and in quality and accessibility of medical care, factors that have not been stringently controlled for to date. In the United States, some studies show a disproportionately high incidence and/or mortality rate for blastomycosis among Black people. In Canada, some studies, but not others, indicate that First Nations people have a disproportionately high incidence of blastomycosis. Incidence in First Nations children may be unusually high. The Canadian data in some areas may be confounded or explained by the tendency to establish indigenous communities in wooded, riparian, northern areas corresponding to the core habitat of B. dermatitidis, often with known B. dermatitidis habitats such as woodpiles and beaver constructions in the near vicinity. Communicability Blastomycosis is not considered contagious, either among humans or between animals and humans. However, there are a very small number of cases of human-to-human transmission of B. dermatitidis related to dermal contact or sexual transmission of disseminated blastomycosis of the genital tract among spouses. History The organisms causing blastomycosis have existed for millions of years. The pathogenic group of onygenalean fungi that give rise to conditions including blastomycosis and histoplasmosis emerged approximately 150 million years ago. The most closely related blastomycosis-causing fungi, Blastomyces dermatitidis and Blastomyces gilchristii, diverged during the Pleistocene, approximately 1.9 million years ago. At the Koster Site in Illinois, evidence pointing to possible blastomycosis infections among Late Woodland Native Americans has been identified. At that site, Dr. Jane Buikstra found evidence for what may have been an epidemic of a serious spinal disease in adolescents and young adults. Several of the skeletons showed lesions in the spinal vertebrae in the lower back. There are two modern diseases that produce lesions in the bone similar to the ones Dr. Buikstra found in these prehistoric specimens: spinal TB and blastomycosis. The bony lesions in these two diseases are practically identical. 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