Harnessing Sewage to Combat Fungal Infections
New research suggests that wastewater could provide valuable insights in detecting dangerous fungal infections.
Fungal infections claim the lives of approximately 2.5 million individuals globally each year, surpassing deaths from tuberculosis and malaria combined. Despite their significant impact, many people are unaware of the fungi responsible, and health systems often lack organized tracking methods to monitor these infections.
The Role of Sewage
Recent findings from my colleagues and I highlight that sewers could be a crucial location for identifying fungal pathogens. While the majority of fungi in our environment are harmless, a small subset poses serious health risks, particularly to individuals with compromised immune systems due to conditions such as cancer, organ transplants, or critical illnesses.
The World Health Organization (WHO) has identified specific fungal pathogens that require enhanced surveillance. Contributing factors such as climate change, an increasing number of immunocompromised individuals, and a limited arsenal of antifungal medications have intensified the threat posed by these fungi.
Understanding the Fungal Threat
One notable example is Candida auris, a yeast first discovered in 2009 in Japan. Since then, it has proliferated worldwide, exhibiting resistance to multiple antifungal treatments and causing challenging outbreaks in hospitals.
Despite their growing prominence, fungal infections do not typically resemble traditional outbreaks seen with viruses like influenza. Instead, they are often perceived as complications of pre-existing health conditions, resulting in a lack of public health attention. For instance, in the UK, laboratories have only been mandated to report cases of C. auris since 2025.
Challenges in Hospital Monitoring
In our review, we identified three primary issues that hinder the detection of fungal infections in hospitals:
- Perception: Fungi are often treated as secondary health concerns.
- Biological Factors: Many individuals carry fungi such as Candida asymptomatically, shedding the organism without showing any illness, thus underestimating its prevalence.
- Technical Limitations: The current fungal testing methodologies are inadequate, and there’s little commercial motivation to enhance them, leading to missed identification of drug-resistant strains.
Innovative Wastewater Surveillance
As people engage in daily activities—including using public restrooms—wastewater serves as an aggregate indicator of community health. Research during the COVID-19 pandemic demonstrated that virus levels in sewage surged 4 to 14 days before reported cases.
Concerning fungi, the evidence remains limited, primarily focusing on C. auris. In a study conducted in Southern Nevada, researchers detected high levels of C. auris in 79% of wastewater samples over ten weeks, particularly around healthcare facilities. Similarly, in Florida, 47% of hospital wastewater samples were positive for the fungus.
While these studies confirm the presence of fungi in wastewater, they do not yet indicate the potential for sewage data to predict outbreaks, as the quantity of fungus shed by individuals is still unknown.
Limitations of Current Testing
Genetic tests can identify fungal DNA but cannot ascertain if the fungus is viable or resistant to treatment. Moreover, because many Candida species are harmless inhabitants of the human body, merely detecting them does not convey meaningful health information.
Integrating genetic testing with culture techniques in labs will enhance efficiency, while it’s important to note that certain fungi, like Aspergillus, are airborne and won’t be found in sewage samples.
Furthermore, environmental studies have found C. auris in unexpected locations, such as remote beaches in the Andaman Islands, illustrating its long-standing presence outside clinical settings.
Toward a Comprehensive Monitoring Approach
While wastewater treatment plants do mitigate pathogens, they are not foolproof, and untreated sewage can overflow into environments like rivers and oceans, potentially fueling resistant strains.
While wastewater monitoring could not replace clinical testing, it can direct public health initiatives toward higher-risk areas, especially where comprehensive patient testing is challenging. Importantly, research is crucial to standardize methods, gauge how much fungus is shed, and establish actionable sewage levels.
The tools for effective monitoring exist, as evidenced by COVID-19 tracking, but prioritizing fungal infections is essential to ensure public health readiness in the face of rising antifungal resistance.
