Surprising Increase in Cases of Rare Fungal Infection Found Across the U.S., New Study Shows
A rare fungal infection known as blastomycosis, which was previously thought to be limited to the northern Midwest and parts of the Southeast, is more common in other areas of the United States than expected, according to a new study published in the Centers for Disease Control and Prevention’s Emerging Infectious Diseases journal. Blastomycosis can be challenging to diagnose as it often mimics other respiratory infections, and delayed diagnosis can make treatment more difficult.
The infection is caused by a fungus called Blastomyces dermatitidis, which thrives in wet soil and decaying organic matter. Blastomycosis is considered an “endemic mycosis,” meaning it only occurs in specific geographic regions. While it is well-known in areas around the Great Lakes, the Ohio River valley, and the Mississippi River valley, it is surprising to find cases of the infection in Vermont.
Dr. Arturo Casadevall, chair of molecular microbiology and immunology at the Johns Hopkins Bloomberg School of Public Health, commented on the unexpected presence of blastomycosis in Vermont, stating, “Vermont is not generally an area you think of when you talk about blastomycosis…but there have been several papers recently suggesting that fungal infections are on the move across the country, and this is one of them.”
The study, led by Dr. Brian Borah, medical director for Vaccine-Preventable Diseases Surveillance at the Chicago Department of Public Health, aimed to determine whether there was an increase in blastomycosis cases or if previously unknown cases were being detected. The epidemiology of other fungal diseases in the country has been changing, indicating that blastomycosis may not be immune to these patterns.
Blastomycosis is a rare infection that can cause respiratory symptoms, fever, and body aches in those who inhale the Blastomyces spores. While most cases are mild, untreated blastomycosis can lead to severe illness or even death. However, one of the challenges in addressing fungal diseases is that they are not required to be reported to public health departments, making it difficult to determine the true prevalence of blastomycosis outside of the five states that have public health surveillance for the disease.
To overcome this limitation, Borah and his team turned to health insurance claims to identify blastomycosis cases in Vermont from 2011 to 2020. The data included claims from Medicare and Medicaid recipients as well as a significant portion of Vermont residents with other health insurance. They discovered 114 cases during the ten-year period, with 30% of patients requiring hospitalization. Vermont had higher rates of blastomycosis compared to all but one of the states with surveillance for the disease.
The study also highlighted the potential factors contributing to the spread of blastomycosis beyond its known endemic regions. Dr. Bruce Klein, a professor at the University of Wisconsin-Madison, explained that fungal pathogens can be transported on shoes during travel, and disturbances in soil can release spores into the air in previously unaffected areas. Climate change is also playing a role, as it alters rain patterns and creates more favorable environments for fungi.
Asiya Gusa, an assistant professor at Duke University, emphasized the impact of climate change on fungal infections, stating, “There’s a fear that with increased humidity and warm, damp weather, we could see a larger accumulation of spores.” Additionally, rising temperatures may force fungi to adapt and survive in the human body, posing further challenges in treating fungal infections.
Diagnosing blastomycosis can be challenging due to its resemblance to other respiratory illnesses. Dr. Klein explained that once Blastomyces dermatitidis spores enter the lungs, they transform into yeast cells that are difficult to treat. Fungal infections are particularly concerning for immunocompromised individuals, but blastomycosis typically affects otherwise healthy people. The severity of the infection may depend on the number of spores inhaled, as the fungus is usually found in small pockets in damp woods.
While most blastomycosis cases are fully treatable with antifungal medications, it can take up to a year to clear an infection that has spread beyond the lungs. The delayed diagnosis of fungal infections is a common issue, especially in areas where these infections are not typically expected. Patients often receive treatment for other respiratory problems before the fungal infection is detected and properly addressed.
In conclusion, the study’s findings shed light on the surprising increase in blastomycosis cases across the United States, including in unexpected regions like Vermont. The changing epidemiology of fungal diseases, coupled with factors such as travel, soil disturbances, and climate change, may contribute to the spread of blastomycosis beyond its known endemic areas. Improved surveillance and awareness are crucial in diagnosing and treating this rare fungal infection to prevent severe illness and fatalities.
