A dangerous, drug-resistant fungus known as Aspergillus fumigatus is rapidly spreading throughout the United States, raising serious public health concerns. The World Health Organization (WHO) has issued a stark warning as rising global temperatures are expected to worsen the situation. This airborne fungus emits microscopic spores that are nearly impossible to avoid and can lead to severe, sometimes fatal, infections—particularly in people with weakened immune systems.
What is Aspergillus fumigatus?
Commonly found in the environment, Aspergillus fumigatus can cause aspergillosis when inhaled. Healthy individuals usually eliminate the spores without issue, but those with compromised immune systems—such as cancer patients, organ or stem cell transplant recipients, and individuals with conditions like HIV, asthma, or chronic illness—are at high risk. In some cases, the infection can be fatal or lead to organ failure.
Aspergillosis appears in several forms, with one of the most dangerous being invasive aspergillosis. This rare condition can spread from the lungs to vital organs like the brain, heart, and kidneys. Another serious form, chronic pulmonary aspergillosis, affects approximately 400,000 people worldwide and leads to long-term lung damage.
Survival statistics are grim. Only 59% of organ transplant recipients survive a year after developing invasive aspergillosis. For stem cell transplant patients, the one-year survival rate falls to just 25%.
Hotspots of Infection in the U.S.
The fungus is expanding fastest in warm, humid regions of the U.S., including Florida, Texas, Louisiana, Georgia, and California. Urban centers such as New York, Houston, and Los Angeles are also vulnerable due to ageing infrastructure and increased exposure to mold in older buildings.
Despite its growing threat, aspergillosis is not a nationally reportable disease in the U.S., meaning there is no standardized data collection on infection or mortality rates. This lack of surveillance makes it difficult for health authorities to assess the true extent of the problem.
Climate Change and Agricultural Practices Fueling the Spread
Rising global temperatures are a major driver behind the fungus’s spread. Aspergillus fumigatus thrives in hot, damp environments and can even endure compost pile temperatures above 120°F. As the planet warms, the fungus is becoming more prevalent in both the natural environment and human hosts.
A recent study from the University of Manchester predicts a potential 75% increase in the fungus’s spread by the year 2100, especially in the southern United States, if fossil fuel emissions are not reduced. The study also notes that climate change may alter agricultural zones and the types of fungal infections that people encounter.
Another critical factor is the widespread use of azole antifungal drugs, commonly applied in both medicine and agriculture. Overuse in farming has contributed to azole resistance in fungal strains, reducing the effectiveness of these medications in treating human infections.
Research has detected azole-resistant Aspergillus fumigatus in agricultural soil across at least seven U.S. states. The intermingling of various fungal strains in soil is producing increasingly robust and drug-resistant variants.
WHO Calls for Urgent Global Response
The World Health Organization has identified Aspergillus fumigatus as a top-priority fungal pathogen due to its escalating drug resistance and significant global death toll.
In response, U.S. hospitals are intensifying mould inspections and employing more potent antifungal treatments. Medical experts advise at-risk individuals to take precautions such as avoiding gardening, staying away from moldy or dusty environments, wearing protective masks, and ensuring clean air indoors.
The WHO is urging immediate international action, calling for quicker diagnostic methods, stronger antifungal drugs, enhanced medical training, and increased funding for the development of new treatments—especially those tailored for children.
With infections rising and the climate becoming more favorable for fungal growth, experts warn that this may be the early stage of a much larger public health crisis.