Blastomycosis Statistics and Maps - Minnesota Dept. of Health

Blastomycosis Statistics and Maps

Blastomycosis is a rare fungal infection caused by Blastomyces species found in soil. Below are graph and maps about human and animal cases.

On this page:
Human Cases
Animal Cases
Annual summaries

Human Cases

From 1999-2020, 834 laboratory-confirmed cases of human blastomycosis were reported to MDH. From 1999-2019, a confirmed case of blastomycosis was defined as a Minnesota resident with (1) a positive Blastomyces culture; (2) Blastomyces organisms visualized in tissue or bodily fluid; or (3) a positive Blastomyces antigen test with compatible clinical illness. Starting in 2020, the CSTE Standardized Surveillance Case Definition for Blastomycosis was adopted. While this definition is more complex, it can be summarized as a confirmed case is defined as a Minnesota resident with compatible clinical illness and (1) a positive Blastomyces culture; (2) Blastomyces organisms visualized in tissue or bodily fluid; or (3) a positive Blastomyces molecular assay; while a probable case is defined as a Minnesota resident with compatible clinical illness and (1) a quantifiably positive Blastomyces antigen test or (2) positive immunodiffusion test for antibodies against Blastomyces.

Graphs and maps

Human blastomycosis cases by year in MN 1999-2017

Human Blastomycosis in Minnesota by Year, 1999-2020 (PDF)

Blastomycosis infections have increased in recent years. In 2020, 84 cases were reported, which is the highest total in the past two decades. Approximately 9% of people with blastomycosis die from the infection.

Human blastomycosis cases in MN by age and gender, 1999-2017

Human Blastomycosis Cases in Minnesota by Age and Gender, 1999-2020 (PDF)

Blastomycosis occurs most frequently in middle-age adults, but cases have been reported in ages from 2 – 93 years. About 70% of all cases are male.

Blastomycosis Patient Demographics and Outcome Data, Minnesota, 1999-2020 (n= 834)

Blastomycosis Patient Demographics and Outcome Data, Minnesota, 1999-2020 (PDF)

The table has data on the age, gender, race, and ethnicity of people with blastomycosis, and what percent were hospitalized or died.

Map of Minnesota blastomycosis cases by County of Residence, 1999-2071

Human Blastomycosis Cases by County of Residence, 1999-2020 (PDF)

In Minnesota, about 1/3 of cases live and are diagnosed in a different county than where they were exposed to Blastomyces. Look at the difference between this map and the next. It is important for health care providers across the state to be aware of Minnesota's endemic areas.

Map of human blastomycosis cases in Minnesota by county of exposure, 1999-2017

Human Blastomycosis Cases in Minnesota by Probable County of Exposure, 1999-2020 (PDF)

While most people are exposed in northern counties, or those along the Mississippi or St. Croix Rivers, this map shows that people can be exposed to Blastomyces in many counties across the state.

Human blastomycosis cases in Minnesota by month of diagnosis, 1999-2017

Human Blastomycosis Cases in Minnesota by Month of Diagnosis, 1999-2018 (PDF)

Blastomycosis is diagnosed slightly more often in the fall and early winter. This is likely due to exposure to the soil-borne fungus in the summer, and an incubation period of 1-3 months.


Animal Cases

  • Blastomycosis occurs most commonly in dogs; however cats and horses have also been known to become infected.
  • From 1999-2020, 1951 laboratory-confirmed cases of animal blastomycosis were reported to MDH. A confirmed case is defined as a Minnesota resident animal with (1) a positive Blastomyces culture; (2) Blastomyces organisms visualized in tissue or bodily fluid; or (3) a positive Blastomyces antigen test with compatible clinical illness.

Graphs and maps

Graph showing the inscidence of Animal Blastomycosis in Minnesota by year 1999-2018

Animal Blastomycosis in Minnesota by Year, 1999-2020 (PDF)
Since 1999, a median of 69 cases of blastomycosis are reported each year in Minnesota animals. However, in the past 5 years, after improving reporting methods, the median has increased to 155 cases/year. Favorable environmental conditions have also likely played a role in these increases, as can be seen in 2019.

Graph of Animal Blastomycosis in Minnesota by Month of Diagnosis, 1999-2018

Animal Blastomycosis Demographics and Outcome Data, Minnesota, 1999-2020 (PDF)
This table has data on the sex, species, type of infection and outcome for animal blastomycosis infections.

Map of Minnesota showing incidence of animal blastomycosis by county of residence Animal Blastomycosis Cases in Minnesota by County of Residence, 1997-2020 (PDF)

In Minnesota, many animals live and are diagnosed in a different county than where they were exposed to Blastomyces. Look at the difference between this map and the next. It is important for veterinarians across the state to be aware of Minnesota's endemic areas.

Map showing animal blastomycosis by county of exposure, 1999-2018 Animal Blastomycosis Cases in Minnesota by Probable County of Exposure, 1999-2020 (PDF)

While many animals are exposed in northern counties, or those along the Mississippi or St. Croix Rivers, this map shows that animals can be exposed to Blastomyces in many counties across the state. Tracking these cases in animals helps us know where humans are also at risk of blastomycosis. For example, cases in dogs appeared earlier than humans in the St. Croix River valley, which helped define that area as endemic.

Graph of Animal Blastomycosis in Minnesota by Month of Diagnosis, 1999-2018

Animal Blastomycosis in Minnesota by Month of Diagnosis, 1999-2020 (PDF)
As with human cases, blastomycosis is diagnosed more often in the fall and early winter. This is likely due to exposure to the soil-borne fungus in the summer, and an incubation period of 1-3 months.

Annual Summary Statistics

Updated Tuesday, 21-Sep-2021 10:38:50 CDT