Experts highlight the increasing presence and emerging risks of three endemic fungal diseases

Experts highlight the increasing presence and emerging risks of three endemic fungal diseases

Infectious disease expert George Thompson has been studying and treating fungal diseases for over two decades. He monitors their spread, symptoms and relative risks. Lately, he's been more concerned about a growing threat: the spread of pathogenic fungi outside their traditional hotspots.

In a commentary published in Annals of Internal Medicine, Thompson and his co-author from the Mycotic Diseases Branch of the Centers for Disease Control and Prevention, Tom Chiller, sounded the alarm. They noted the increasing presence and emerging risks of three endemic fungal diseases: histoplasmosis, blastomycosis and coccidioidomycosis (valley fever).

“These three fungal diseases typically inhabit specific U.S. regions that are conducive to their survival,” Thompson said. He is a professor at the UC Davis School of Medicine in the Division of Internal Medicine, Division of Infectious Diseases, and the Division of Medical Microbiology and Immunology. “Recently we are finding more cases of these diseases outside their known areas, which surprises clinicians and patients.”

Fungal infections are an emerging global threat

Fungi are microorganisms that occur abundantly in nature. These include yeasts, molds, fungi and more. While most fungi are harmless to humans, some can cause diseases (known as mycoses) that can have devastating consequences for patients and the healthcare system.

Recently, the World Health Organization (WHO) published its list of priority fungal pathogens, identifying the fungi of most concern that can cause infections for which drug resistance or other treatment problems exist. These pathogens are expected to cause even more problems over the next decade.

Climate change increases the spread of fungal infections

Endemic fungi traditionally have different geographical distributions. Climate changes in temperature and rainfall affect where these fungi thrive.

The authors noted the expanding regions harboring the endemic fungi. Valley fever, for example, was found in Nebraska, far east of its traditional hotspots in California and Arizona.

The organisms are probably much more widespread than we originally thought. There is an increasing likelihood that clinicians unfamiliar with these organisms will encounter them in their daily practice.”

George Thompson, P Professor, UC Davis School of Medicine

Doctors often miss the diagnosis of a fungal infection

The three endemic mycoses have many symptoms, including fever, chills, cough, night sweats and fatigue. They can also cause lung infections that mimic pneumonia. Therefore, they can easily be confused with more common viral and bacterial lung infections.

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Current pneumonia guidelines from the American Thoracic Society and the Infectious Diseases Society of America do not provide specific testing or treatment recommendations for endemic mycoses. Most doctors may have little experience in recognizing and treating these fungal lung infections.

About 20% of pneumonia cases in some parts of California and Arizona are caused by Valley fever. However, it usually takes more than three weeks after symptoms begin for the correct diagnosis to be made. It can take even longer to diagnose histoplasmosis and blastomycosis.

Fungal infections are also often misdiagnosed as bacterial. When this misdiagnosis occurs, the patient is prescribed antibiotics that are ineffective for fungal diseases. This also exposes them to unnecessary medications and contributes to the rise of antimicrobial resistance in the community. The authors urged doctors to take a thorough travel history and perform further tests to rule out a fungal infection before giving patients a second round of antibiotics.

“In regions where these fungal diseases thrive, physicians must consider diagnosing and testing for mycoses in all patients with suspected disease,” Thompson recommended.

The authors identified several factors that may contribute to these diagnostic and treatment delays. One is variation in clinicians' knowledge of disease diagnosis and treatment. Another reason is the lack of point-of-care diagnostics. Panels typically used for the diagnosis of respiratory infections do not include the endemic mycoses. Serum antibody and urine antigen tests for endemic mycoses are typically only available from certain laboratories.

Action plan for dealing with endemic mycoses

The authors see an opportunity to improve fungal diagnosis and treatment practices through better surveillance and continued medical education of these regional infections. They proposed a multi-pronged approach to aid in prevention efforts and timely detection and treatment of these diseases. They demanded:

1) national surveillance and reporting of endemic mycoses in both humans and animals

2) Patient and provider education efforts

3) Inclusion of endemic mycoses in future pneumonia guidelines

4) Development of point-of-care diagnostic tools

5) Researching a pandemic mycoses vaccine to prevent infections

Source:

University of California-Davis Health

Reference:

Thompson III, GR, et al. (2022) Endemic Mycoses: Underdiagnosed and Underreported. Annals of Internal Medicine. doi.org/10.7326/M22-2371.

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