Endemic Mycoses: Better Diagnosis and Reporting Needed

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Blastomycosis, coccidioidomycosis (Valley fever), and histoplasmosis are the most prevalent endemic fungal diseases (mycoses) in North America. Authors of an opinion piece in Annals of Internal Medicine argue that we need to improve the diagnosis and reporting of these infections to better serve patients and understand the scope of the problem.

Traditionally, these infections have had known regions of endemicity, allowing for the targeted education of clinicians and community members. Unfortunately, these regions’ boundaries appear to be changing because of the changing climate.

Lead author George R. Thompson III, MD, professor of medicine at the University of California, Davis, told Medscape Medical News in an email, “These mycoses are increasingly recognized outside of the traditional regions of endemicity. The regions where they occur are expanding.”

Underdiagnosed and Underreported

Because these environmentally acquired mycoses present as community-acquired pneumonia (CAP) or with other nonspecific symptoms such as night sweats, fever, chills, cough, or fatigue, providers often mistakenly treat patients for a bacterial or viral illness, not suspecting a fungal pathogen. Overlooking mycoses leads to treatment delays, multiple unnecessary and potentially harmful courses of antibiotics, not to mention excess healthcare expenses and healthcare utilization.

Even in areas where mycoses are known to be endemic, fungal diseases can often be overlooked, says Fariba Donovan, MD, PhD, assistant professor of medicine at the University of Arizona’s Valley Fever Center for Excellence (VFCE), in Tucson. (Donovan was not involved in the Annals article.) Tucson is in an area considered hyperendemic for Valley fever. In hyperendemic regions of Arizona and California, Valley fever is thought to be the causal agent for approximately 20% of CAP cases.

Even with this increased regional awareness, Donovan’s research showed that 43% of Valley fever patients at Banner University Medical Center in Tucson had diagnostic delays of more than 1 month, and the median delay was 23 days. “The most important aspect of Valley Fever early diagnosis is the awareness among medical communities,” she told Medscape Medical News. VFCE provides regular education about Valley fever for medical personnel and members of the community.

In addition to the general lack of awareness, the Annals authors point out that endemic mycoses are not included on common laboratory diagnostic panels used for pneumonia patients. Serum antibody and urine antigen tests for the endemic mycoses are typically available only from certain laboratories, so providers need to be trained to order them.

Endemic mycoses are also not specifically addressed in the professional guidelines for physicians to follow about CAP. For example, the 2019 joint guideline for community-acquired pneumonia from the American Thoracic Society and the Infectious Diseases Society of America does not directly address the issue of when to suspect endemic mycoses. 

The Epidemiology of Endemic Mycoses

A region’s temperatures and precipitation patterns are important to the ecology of mycoses, so climatic changes can lead to geographic changes in endemicity. Wildfires may also play a role in dissemination of some of these organisms. For the sake of human and nonhuman patients, the authors argue that the current maps must be redrawn.

In recent years, researchers have discovered Valley fever among nontravelers in Nebraska, much farther east than the historic hot spots of Arizona and California. Similarly, researchers and clinicians are finding histoplasmosis and Blastomyces infections in areas well outside of what were previously thought to be their endemic areas.

If county, state, and federal public health authorities don’t specifically mandate that a certain pathogen be reported to them, epidemiologic data won’t consistently be collected from providers and diagnostic laboratories. Lack of data means lack of awareness among providers who may fail to consider mycoses in a differential diagnosis.

These endemic mycoses often infect nonhuman animals as well, so the authors recommend increased surveillance and reporting of veterinary infections, arguing that that could help determine current borders for endemicity maps. “The much greater number of animals and their higher environmental exposure places them at greater risk of encountering these infections,” Thompson explained.

Five Suggestions to Help Improve Diagnosis and Reporting

The authors have five suggestions to improve rates of diagnosing and reporting endemic mycoses:

1. National surveillance and disease reporting of endemic mycoses in human and veterinary patients

2. Education directed at providers and patients

3. Inclusion of endemic mycoses in future CAP guidelines

4. Development of point-of-care diagnostics to decrease the time from patient presentation to diagnosis and receipt of effective therapy

5. Exploration of a pan-endemic mycoses vaccine to prevent infection

Thompson recommends: “In regions where these fungal diseases flourish, doctors need to consider the diagnosis and testing for mycoses in all patients with suggestive illness.”

Ann Intern Med. Published online November 22, 2022. Abstract. doi:10.7326/M22-2371.

This research received financial support from the National Institutes of Health (5U19AI166798-02) and the UC-Davis Burden Family Gift Fund for Research on Coccidioidomycosis. Thompson and Donovan report no relevant financial relationships.

Erin Archer, RN, BSN, CIC is a registered nurse, freelance writer, and infection preventionist in Tucson, Arizona.

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