Climate Change and Fungal Diseases of the Lung

Unlike humans, many pathogenic fungi are thriving as Earth’s temperature increases, quickly adapting to higher temperatures and becoming more virulent. As new pathogenic fungi emerge and known fungal pathogens spread and evolve, physicians need to be more attentive.

Three of the more common fungal diseases of the lung – histoplasmosis, blastomycosis, and coccidioidomycosis – are geographically located based on climate. As the climate changes, so will their locations, and there is a need to be aware of their presence in new areas, both in the United States and elsewhere.

HISTOPLASMOSIS

Histoplasmosis capsulatum is a fungus which lives in soil associated with bird and bat droppings. The common areas it has been found have been in the Ohio and Mississippi River Valleys, including southern Illinois and Missouri. Temperature increases have expanded the areas of where histoplasmosis can be found to Montana, California, and now Canada. Warm temperatures and extreme storms increase the release of spores in the air. Climate change can increase the distribution of birds and bats and increase transmission seasons. Brazil, Argentina, and Colombia have a higher incidence, and new disease has been found in parts of Asia.

BLASTOMYCOSIS

Blastomyces dermatitidis is a fungus primarily found in moist soil and decomposing organic matter like wood and leaves. Traditionally, this fungus has been prevalent in the areas around the Great Lakes, the Ohio and Mississippi River Valleys, and the southeastern United States. Increases in temperature and humidity have added the northeastern United States, parts of Canada, and parts of Europe to the areas where Blastomycosis dermatitidis can be found. The extreme weather patterns such as intense storms, flooding, and hurricanes play a significant role in the dispersal of fungal spores. Shifts in wildlife populations and migration patterns can also aid further in the spread of Blastomyces dermatitidis.

If Blastomycosis dermatitidis is not included in the differential diagnosis and is not tested for, it frequently can be mistaken for lung cancer. Healthcare professionals and public health authorities need to become vigilant about the presence of the disease and its potential impact on public health.

COCCIDIOIDOMYCOSIS (VALLEY FEVER)

Coccidioides is a fungus found in arid soil in warm dry conditions in the southwestern United States, Mexico, and Central and South America. The CDC reports 10,000 - 20,000 cases a year. It is thought that the actual prevalence is 10-18 times higher. The CDC reports this year that in 2023 California reported 9,054 cases, 39 percent higher than the previous year. During April 2023-March 2024 California reported 10,519 cases. It is thought to be the cause of 15-30 percent of community-acquired pneumonia in Phoenix and Tucson.

Increased droughts, dust storms, and wildfires can increase the spread of spores. Heavy rainstorms followed by droughts increase both the growth and spread of spores. California had record high numbers in 2023. The Pacific Northwest is now included in the vulnerable region for the spread of Coccidioides. Models suggest that it could spread to Idaho, Wyoming, Montana, Nebraska, and North and South Dakota by 2100, increasing the affected states from 12-17 per the Journal Geo-Health.

PUBLIC HEALTH AND MITIGATION

There are an increased number of cases of fungal diseases of the lung. The risk of these cases increases with the season, dust, soil exposure, age of the patient, and certain underlying diseases or conditions. HIV/AIDS, transplant immunosuppression, immunosuppressing drugs place patients at higher risk of infection. Increased monitoring, driving with windows up in endemic areas, and avoiding dust storms and disturbed soil can further reduce the risk of infection. Consideration should also be given to efforts to curb occupational exposure for high-risk employees such as outdoor workers, farmers, and others with N-95 masks.

References 

Emerg Infect Dis: 2018 Jul;24(7):1257–1266. doi: 10.3201/eid2407.172063 Geohealth: 2019 Oct 10;3(10):308–327. doi: 10.1029/2019GH000209 Appl Environ Microbial: 2022 Mar 9;88(7):e02010-21. doi: 10.1128/aem.02010-21 WWW.CDC.GOV VALLEY FEVER April 24, 2024 WWW.CDC.GOV BLASTOMYCOSIS WWW.CDC.GOV COCCIDIOIDOMYCOSIS Stud Mycol: 2020 Mar 2;97:100095. doi: 10.1016/j.simyco.2020.02.001

Salazar-Hamm, P., Torres-Cruz, T.J. The Impact of Climate Change on Human Fungal Pathogen Distribution and Disease Incidence.Curr Clin Micro Rpt 11, 140–152 (2024). https://doi.org/10.1007/s40588-024-00224-x

Bonifaz, A., García-Salazar, E. & Frías-De-León, M.G. Climate Change Exacerbating Fungal Disease Disparities. Curr Fungal Infect Rep 18, 1–12 (2024). https://doi.org/10.1007/s12281-023-00479-9

JAMA March 18, 2025 Volume 333 #11 Climate change and Coccidiodomycosis.

Emerg Infect Dis: 2025 March 18 doi:10.3201/eid 3105.241338