Wastewater tracking catches hospital fungus before patients show symptoms

A new UNLV-led wastewater surveillance study brings scientists one step closer in the global race to detect and deter skyrocketing cases of a potentially deadly drug-resistant fungus that puts hospital patients at risk of serious blood, heart, or brain infections.

Candida auris presents ongoing challenges for Nevada's healthcare facilities. In 2025, the Silver State on its own accounted for 22% of the nation's nearly 7,200 C. auris cases - reporting 1,605 infections to the Centers for Disease Control and Prevention, and outpacing California's roughly 1,550 cases and Texas' 830. When adjusted for population, Nevada logged 20 times more cases per capita than its coastal neighbor.

UNLV-led research published in 2023 was the first to prove the efficacy of using sewer surveillance to detect C. auris in untreated wastewater pulled from a wastewater treatment plant. And now, the university - in collaboration with the Southern Nevada Water Authority, Southern Nevada Health District, Auburn University, Nevada State Public Health Laboratory at the University of Nevada, Reno, and several local wastewater agencies - has built on that foundational work with an online-first study to be published in Nature Communications. 

The new paper reveals that sampling raw wastewater closer to the source - sewer lines that directly serve hospitals, retirement homes, and long-term care facilities where C. auris cases tend to originate and pose the greatest public health risk - allows scientists to detect drug-resistant strains of the pathogen as many as five months before patients begin showing symptoms.

These findings open a new frontier for hospitals, which will no longer have to rely solely on clues in clinical records or case-by-case testing on individuals who are already ill."

Edwin Oh, study co-author, professor and director, Center for Water Intelligence and Community Health, UNLV

"Wastewater surveillance provides a non-invasive, facility-scale biopsy of a hospital community. And we can get answers on a daily basis, paving the way for health facilities to save lives by figuring out sooner when pathogens resistant to a standard course of antifungal treatment are present," Oh continued. "When you complement surveillance with clinical testing, you can detect drug-resistant pathogens months earlier and give clinicians the window they need to change course before an outbreak takes hold." 

C. auris, also known as Candidozyma auris, is a fungus that can cause serious wound, bloodstream, or organ infections - particularly in patients who are immunocompromised, have pre-existing health conditions, are in long-term healthcare settings, or are undergoing treatment with invasive medical devices such as a catheter. C. auris is not a risk to drinking water systems, but infection prevention and control in healthcare facilities is challenging because the fungus can grow on both dry and moist surfaces, such as furniture, door handles, clothing, and medical equipment. It's also shown resistance to many commonly used surface disinfectants and all three types of antifungal medicines. More than 1 in 3 patients with invasive C. auris infections dies.

With Nevada having sustained the largest recorded C. auris outbreak in U.S. history since 2022, the scientists say their efforts to eradicate the fungus are critical. 

Their Nature Communications study compared untreated wastewater pulled from centrally located municipal wastewater treatment plants with higher resolution samples from the sewer lines serving three major Southern Nevada hospitals between 2021 and 2024. And they called the results "striking": Wastewater sampled directly from the hospital sewers yielded C. auris concentrations nearly 100 times higher than the community-scale wastewater treatment plants, with 95% versus 18% detection rates. 

The study also uncovered unexpected biological insights into how the fungus adapts to drug pressure. Resistant strains showed signs of metabolic rewiring and novel stress response mechanisms that could point toward new therapeutic targets. 

"Since 2020, wastewater surveillance has proven to be tremendously valuable for understanding community transmission of diseases like COVID-19 and influenza," said study co-author Daniel Gerrity, a principal research laboratory scientist at the Southern Nevada Water Authority. "These new results highlight the benefits of implementing this emerging public health tool closer to healthcare facilities, potentially leading medical professionals toward more effective treatment options for their patients." 

The research team rolled the data into building one of the world's largest C. auris repositories. And the next step is to pair the genomes with molecular tools and start developing new antifungal therapeutics - and perhaps even a vaccine that wards off these drug-resistant pathogens. 

"Too often, a patient's own illness is the first signal that a drug-resistant strain has arrived in a facility, and by then it may already be spreading," said study co-lead author Ching-Lan (Lanie) Chang, a neuroscience doctoral student at UNLV. "Wastewater surveillance changes that timeline, giving healthcare workers, patients, and their families a head start that simply didn't exist before. New antifungal treatments and a vaccine remain longer-term goals, but the genomic repository we've built from this work lays the groundwork. In the meantime, wastewater intelligence gives us the ability to act right now."