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As the United States faces the grim prospect of losing its hard-won measles elimination status, scientists are turning to an innovative, often overlooked, source for early detection and containment: wastewater. This sophisticated approach, building on lessons learned during the COVID-19 pandemic, offers a powerful new tool in the ongoing battle against this highly contagious and potentially deadly disease.
The year 2025 has marked an alarming resurgence of measles in the United States. A significant outbreak that began in Texas a year ago has now spread, leading to over 2,500 confirmed cases nationwide since the start of January. Tragically, three lives have been lost to the virus, a stark reminder of measles’ persistent threat. This surge coincides with a global trend of declining vaccination rates, a factor directly linked to the rise in outbreaks across various regions, including Europe, Southeast Asia, and the Eastern Mediterranean.
The World Health Organization (WHO) reports that while global measles deaths have seen a remarkable 88% decrease between 2000 and 2024, largely due to widespread vaccination efforts that have saved an estimated 59 million lives, the virus remains a formidable challenge. In 2024 alone, an estimated 95,000 people died from measles, with young children disproportionately affected. The United States, which had proudly achieved measles elimination status, is now on the verge of losing it, mirroring Canada’s experience where over 5,000 cases in just over a year led to the revocation of its elimination status in November 2024.
Traditionally, public health strategies for controlling measles have relied on clinical monitoring within healthcare settings and robust vaccination campaigns. However, the limitations of these methods, particularly in reaching underserved populations or identifying asymptomatic cases, have spurred the exploration of alternative surveillance techniques. Wastewater analysis has emerged as a promising solution, leveraging the fact that our wastewater systems act as a vast, collective biological sample, containing traces of viruses, bacteria, and other pathogens shed by individuals in a community.
The concept of using wastewater to track infectious diseases is not new, but it gained significant traction during the COVID-19 pandemic when scientists discovered that the SARS-CoV-2 virus was shed in feces. This breakthrough paved the way for initiatives like WastewaterSCAN, an academic-led program co-founded by Marlene Wolfe of Emory University and Alexandria Boehm of Stanford University. This program aims to analyze wastewater samples across the US, expanding its surveillance capabilities beyond COVID-19.
Marlene Wolfe had previously highlighted the potential of wastewater surveillance for measles, noting that the measles virus is shed in urine, making it detectable in sewage. The hope was that this approach could provide crucial insights into measles outbreaks in communities, even among individuals who might not have access to healthcare or receive a formal diagnosis. It could also serve as an early warning system, pinpointing areas where public health officials needed to intervene to prevent further spread. While initial evidence was limited, the concept held immense promise.
Building on this potential, Wolfe and her colleagues developed a test capable of identifying measles RNA. They conducted a pilot study at two wastewater treatment plants in Texas between December 2024 and May 2025, collecting samples multiple times a week and testing them for the presence of measles RNA. The results, published in a preprint on medRxiv and currently under peer review, were highly encouraging. Measles RNA was detected in 10.5% of the collected samples. Crucially, the first detection occurred a full week before the first official measles case was confirmed in the surrounding area. This early detection capability suggests that wastewater surveillance could provide public health officials with a vital head start in managing and mitigating outbreaks.
Further promising results have emerged from a Canadian research team. Mike McKay and Ryland Corchis-Scott at the University of Windsor, Ontario, along with their colleagues, have also been actively testing wastewater for measles RNA. Between February and November 2025, they collected samples from a wastewater treatment facility serving over 30,000 residents in Leamington, Ontario.
While wastewater tests can indicate the presence of measles in a community, they typically cannot identify specific infected individuals, the exact locations of infections, or the precise number of cases. However, McKay and his team are making strides in addressing these limitations. By using tampons to absorb wastewater from a hospital’s lateral sewer, they were able to compare their measles test results with the number of clinical cases within that hospital. This comparison allowed them to estimate the virus’s "shedding rate." When they applied this data to the samples from the Leamington treatment facility, their estimates of measles cases significantly exceeded the officially reported figures. These findings align with the estimations of local health officials, who believe the actual number of cases during the outbreak was five to ten times higher than confirmed counts, as detailed in a recent preprint on medRxiv.
Despite these advancements, inherent limitations to wastewater surveillance remain. As Ryland Corchis-Scott notes, analyzing the collective waste of an entire community makes it challenging to extract information about individual infections. Marlene Wolfe acknowledges that there is still much to learn about optimizing these tools for maximum utility. Nevertheless, her team at WastewaterSCAN has been consistently monitoring wastewater for measles across the US since May 2024, with their findings openly shared with public health officials online.
The impact of this data is already being felt. Public health departments are actively using these findings to inform their responses. In some instances, this has led to the issuance of health alerts and increased vaccination efforts in targeted areas. Wolfe emphasizes that public health departments, clinicians, and families are increasingly relying on this information to protect themselves and their communities.
The Ontario outbreak, for which McKay’s team was testing, has now been declared over. While testing has paused, McKay believes their research strongly advocates for the sustained implementation of a wastewater surveillance system for measles. He suggests that such a system could be instrumental in helping Canada regain its measles elimination status, demonstrating a proactive and effective approach to public health. The ability to swiftly identify and contain outbreaks through advanced wastewater monitoring could indeed be a powerful tool for demonstrating Canada’s commitment to controlling infectious diseases.
