Blastomycosis Risk & Prevention

Who gets blastomycosis?

Image of a campsite with a fire

Anyone can get blastomycosis if they are in an area where Blastomyces lives in the environment, but only about half of people who are infected develop symptoms. People who participate in outdoor activities that expose them to wooded areas (such as forestry work, hunting, and camping), moist soil (such as by lakes or rivers), and disturbed soil (such as through digging or excavation), may be at greater risk for getting blastomycosis.1 Some racial and ethnic groups may have higher rates of Blastomyces infection or hospitalization.2,3 Certain groups of people may be at greater risk for developing severe blastomycosis, such as:

  • People who have weakened immune systems, for example, people who4:
    • Have advanced AIDS
    • Have had an organ transplant
    • Are taking medications such as corticosteroids or TNF-inhibitors
  • Pregnant people

How it spreads

Blastomycosis does not usually spread between people or between people and animals. In extremely rare cases, blastomycosis has been spread between infected people or animals through needlestick injuries, bites, or sexual contact.

Pets and blastomycosis

Pets, particularly dogs, can get blastomycosis, but it does not spread between animals and people.5 The symptoms of blastomycosis in animals are similar to the symptoms in humans. People concerned about your pet’s risk of getting blastomycosis or who think their pet has blastomycosis, should talk to a veterinarian.

Risks at work

Certain jobs may increase risk for blastomycosis.

Outdoor or construction workers

Blastomyces lives only in certain areas of the world.

Blastomyces live in soil and decaying matter. People whose jobs involve disturbing soil or plant matter (for example, digging, excavation) in these areas are at increased risk for blastomycosis.

Laboratory scientists

Blastomyces can be transmitted through needlestick injuries and breathing in conidia (spores) from fungal cultures (samples).6,7 There is no evidence showing that antifungal medication (i.e., prophylaxis) prevents people from getting sick with blastomycosis after exposure to Blastomyces.


Although rare, blastomycosis can also be transmitted through needlestick injuries and animal bites.8,9 If you develop symptoms of blastomycosis, contact your healthcare provider.

What to do

People who have occupations that increase their risk for blastomycosis should see a healthcare provider right away if they develop symptoms. It is important to get diagnosed early. Blastomycosis is treatable with antifungal medicines.

Anyone who thinks they were exposed to Blastomyces at work, should contact their crew leader or supervisor and their Occupational Health, Infection Control, Risk Management Department. In workplaces without these services, they should contact their local city, county, or state health department.


There is no vaccine to prevent blastomycosis, and it may not be possible to completely avoid being exposed to the fungus that causes blastomycosis in areas where it is common in the environment. People who have weakened immune systems may want to consider avoiding activities that involve disrupting soil in these areas.

  1. Saccente M, Woods GL. Clinical and laboratory update on blastomycosis. Clin Microbiol Rev. 2010 Apr;23(2):367-81.
  2. Smith DJ, Williams SL, Endemic Mycoses State Partners Group, Benedict KM, Jackson BR, Toda M. Surveillance for Coccidioidomycosis, Histoplasmosis, and Blastomycosis — United States, 2019. MMWR Surveill Summ 2022;71(No. SS-7):1–14.
  3. Benedict K, Gibbons-Burgener S, Kocharian A, Ireland M, Rothfeldt L, Christophe N, Signs K, Jackson BR. Blastomycosis Surveillance in 5 States, United States, 1987-2018. Emerg Infect Dis. 2021 Apr;27(4):999–1006.
  4. Pappas PG, Threlkeld MG, Bedsole GD, Cleveland KO, Gelfand MS, Dismukes WE. Blastomycosis in immunocompromised patients. Medicine. 1993;72(5):311–25.
  5. Brömel C, Sykes JE. Epidemiology, diagnosis, and treatment of blastomycosis in dogs and cats. Clin Tech Small Anim Pract. 2005 Nov;20(4):233-9.
  6. Stevens DA, Clemons KV, Levine HB, Pappagianis D, Baron EJ, Hamilton JR, et al. Expert opinion: what to do when there is coccidioides exposure in a laboratory. Clin Infect Dis 2009 Sep;49(6):919–923
  7. Denton JF, Di Salvo AF, Hirsch ML. Laboratory-Acquired North American Blastomycosis. Laboratory-acquired North American blastomycosis. JAMA. 1967;199(12):935–936.
  8. Gnann JW, Bressler GS, Bodet CA, Avent CK. Human blastomycosis after a dog bite. Ann Intern Med. 1983 Jan;98(1):48-49.
  9. Ghatage P, Pierce KK, Wojewoda C, Mendelson N, Wilcock J, Nesbit R, et al. A veterinarian from Vermont presenting with a painful right index finger following a needlestick injury that occurred while caring for a dog. Clin Infect Dis. 2020 Sep;71(6):1577–1579.