New research suggests that nearly 10% of patients hospitalized with pneumonia in certain regions test positive for Coccidioides, though many cases remain undiagnosed.


RT’s Three Key Takeaways:

  1. Leading Pathogen: Researchers found that Coccidioides was the most frequently detected organism among patients hospitalized for community-acquired pneumonia in an endemic region.1
  2. Diagnostic Indicators: Patients presenting with night sweats, rashes, headaches, or eosinophilia were more likely to test positive for the fungal infection than those with other symptoms.1
  3. Hospital Efficiency: Early identification of Valley Fever was associated with a shorter hospital length of stay, providing an institutional incentive for universal testing in endemic areas.1


Coccidioides, the fungus responsible for coccidioidomycosis or Valley Fever, is the most frequently identified cause of community-acquired pneumonia (CAP) among hospitalized adults in endemic regions, according to a study published in Open Forum Infectious Diseases.1

Researchers from the Mayo Clinic reviewed the records of 1,141 patients hospitalized for pneumonia at a tertiary care center in Maricopa County, Arizona, between November 2024 and October 2025. The study found that while 75.8% of these patients underwent testing for coccidioidomycosis, 9.8% of those tested returned positive results.1

The Centers for Disease Control and Prevention (CDC) reports between 10,000 and 20,000 cases of Valley Fever annually, but the study authors noted that the true incidence is likely 10 to 18 times higher due to underreporting and missed diagnoses. The researchers estimated that in their specific cohort, approximately 25 to 30 additional cases of coccidioidomycosis may have been missed among the patients who were not tested.1

The study identified specific clinical factors that influenced whether a patient received a test and whether that test was likely to be positive. Clinicians were more likely to order coccidioidal testing when patients presented with fever, shortness of breath, fatigue, or radiographic findings suggestive of a fungal infection.1

However, the data revealed that certain symptoms were more predictive of a positive result. Patients who experienced night sweats, rashes, or headaches were more likely to have a confirmed Coccidioides infection. Additionally, higher median eosinophil counts were associated with coccidioidomycosis compared to noncoccidioidal illnesses.1

The research highlighted a significant correlation between early diagnosis and hospital efficiency. When Coccidioides was identified early as the cause of CAP, the patient’s hospital length of stay was shorter than that of patients with noncoccidioidal pneumonia, even when accounting for other comorbid conditions.1

“A shorter length of stay could be an institutional incentive to test all patients with CAP for coccidioidal infection,” the researchers wrote in the study.1

The study also addressed the challenge of co-infections. One-third of the patients who tested positive for Valley Fever also had a second bacterial or viral pathogen identified during their evaluation. This suggests that the presence of another organism, such as SARS-CoV-2 or Staphylococcus aureus, does not definitively rule out a fungal infection.1

While testing rates at the tertiary care facility (75.8%) were significantly higher than those reported in outpatient or urgent care settings—which typically range from 2% to 21.5%—the authors recommended that all patients hospitalized with CAP in endemic areas undergo universal testing.1

The study noted several limitations, including its focus on a predominantly White population at a single tertiary care facility, which may not represent all patient demographics. Because the study was observational, researchers stated that causality between specific patient factors and positivity rates could not be firmly established.1


Reference

  1. Saima N Tisekar, Yehia S Aboalmaaty, Gretchen E Taylor, Janis E Blair, Coccidioidomycosis Testing Among Patients Hospitalized With Community-Acquired Pneumonia, Open Forum Infectious Diseases, Volume 13, Issue 8, August 2026, ofag499, https://doi.org/10.1093/ofid/ofag499 https://academic.oup.com/ofid/article/13/8/ofag499/8752405