What to know
- Case counts for blastomycosis show a yearly incidence (infection rate) of ≤2 cases per 100,000 population.
- The estimated annual death rate among hospitalized patients for blastomycosis usually ranges from 8%-10%, although it increased to 17% in 2021.
- Reported case and death counts for blastomycosis are lower than the actual number of infections due to limited testing and reporting. The actual number of infections in the United States is unknown.
Rates of infection
The reported yearly incidence (infection rate) of blastomycosis is around ≤2 cases per 100,000 population. Rates may vary substantially between and within states. Wisconsin reports the highest incidence of blastomycosis of any state; yearly incidence rates range from 10 to 40 cases per 100,000 people in some northern counties.
Reported case counts for blastomycosis are lower than the actual number of infections, though it's unknown how much lower. Blastomycosis is often undiagnosed or misdiagnosed, and very few states report blastomycosis cases.
Deaths due to blastomycosis
An estimated 8–10% of patients hospitalized with blastomycosis die annually in the United States. In 2021, the death rate among patients hospitalized with blastomycosis sharply increased to 17% according to the most recent data analysis, likely impacted by the COVID-19 pandemic.
Public health surveillance
Blastomycosis is a reportable fungal disease in select states. Check with your state, local, territorial or tribal health department about disease reporting requirements and procedures in your area.
Blastomycosis outbreaks
Outbreaks of blastomycosis are rare. Outbreaks are defined as two or more cases linked to a common source or area. Outbreaks have been linked to activities that disrupt soil or plant matter, like construction, excavation, or outdoor activities like camping.
It can be challenging to identify the source of a blastomycosis outbreak. Blastomyces, the fungus that causes blastomycosis, is difficult to detect in the environment.
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