Wastewater surveillance could detect dangerous fungal pathogens like Candida auris before outbreaks

A Nature article argues that wastewater testing could help track dangerous fungal pathogens, notably Candida auris, by capturing a snapshot of community fungal shedding. This approach could provide an early warning for outbreaks and guide targeted public health actions, complementing hospital-based testing. The piece also outlines the current limitations and what needs to happen to turn sewage data into actionable signals.

• Wastewater reflects community shedding of fungi, potentially predisposing clinical cases to be detected earlier
• Candida auris is a global, drug resistant fungus that has caused hospital outbreaks
• Standardised methods, understanding of fungal shedding, and linking sewage data with hospital and animal health are essential

From Nature.

Overview and context

Each year fungal infections claim about 2.5 million lives worldwide, exceeding the combined toll of tuberculosis and malaria. A Perspective published in Nature argues that looking to the sewer could help identify fungal pathogens that are typically overlooked by health systems. Fungi are ubiquitous and usually harmless, but a subset causes serious illness in people with weakened immune systems. The World Health Organization has published a list of priority fungal pathogens in urgent need of better surveillance. Climate change, rising numbers of immunocompromised people, and a limited arsenal of antifungal drugs are creating favorable conditions for dangerous fungi to spread and adapt, including some that can tolerate human body temperature and hospital environments.

Why surveillance in hospitals misses fungi

The authors identify three main problems that hinder hospital based monitoring of fungi. First, fungi are treated as a secondary concern, not a primary public health issue. Second, many people carry fungi such as Candida in their gut or on the skin for extended periods without illness, shedding fungal material throughout, which hospital tests often miss because they focus on those who become seriously ill. Third, fungal diagnostics are limited and lack strong commercial incentive for improvement; many labs do not identify yeasts to the species level, potentially allowing drug resistant species to go undetected. These gaps mean real spread and dynamics of fungal pathogens are underestimated.

Wastewater as a community snapshot

The article highlights wastewater as a natural, collective sample of a community. It notes that during COVID-19, sewage levels rose days before confirmed cases, suggesting sewage data can precede clinical surveillance. For fungi, the evidence is thinner and largely focused on Candida auris. Studies in southern Nevada detected C. auris DNA in a large share of wastewater samples, Florida hospital effluent showed higher positivity than downstream treatment plants, and a UK hospital outbreak was reflected in ward wastewater. While these findings demonstrate feasibility, they do not yet prove that sewage data can forecast outbreaks or quantify the number of affected individuals.

Technical and interpretive limitations

Several caveats limit the current wastewater approach. Genetic detection methods reveal DNA but do not confirm whether the fungus is alive or drug resistant; many Candida species are harmless colonizers, so detection alone is not predictive. Some pathogenic fungi, such as Aspergillus, are inhaled and may not pass through the gut, limiting sewage’s coverage of all fungal diseases. The authors also note that modelling the relationship between sewage concentrations and community disease burden requires understanding how much individual patients shed, how shedding varies by species, and how environmental processes affect DNA signal persistence.

Path forward and integration with public health

The Perspective calls for standardisation of methods across laboratories, measurement of how much fungi people shed, and the development of action thresholds that would trigger targeted testing in hospitals, clinics, and farms. It also argues for linking wastewater data with other surveillance streams, including hospital data, animal health monitoring, and environmental sources near wastewater treatment works. The tools demonstrated in the COVID-19 era show the potential for sewage based surveillance, but political will and investment are needed to prioritise fungal pathogens and to translate sewage signals into concrete public health actions.

Conclusion

Wastewater monitoring should not replace patient based testing but can direct health services to where to focus resources, especially in settings where population testing is limited. Achieving this potential will require methodological standardisation, better understanding of fungal shedding, and a concerted effort to connect sewage data with hospital and agricultural monitoring. The authors argue that fungi have rightly received less attention, but they may be the next resilient threat—unless wastewater based surveillance helps to anticipate and counter outbreaks.

From Nature.