Wastewater Surveillance Detects Measles Before Outbreaks in Texas

In early January 2025, researchers in Houston detected the measles virus in wastewater samples, signaling potential outbreaks before any clinical cases were reported. This proactive surveillance underscores the escalating measles resurgence in Texas, driven by declining vaccination rates.

The detection of measles in wastewater highlights the effectiveness of environmental surveillance in early disease identification. Coupled with increasing measles cases and decreasing vaccination coverage, these findings emphasize the urgent need for robust public health interventions to prevent widespread outbreaks.

Measles, a highly contagious viral disease, was declared eliminated in the United States in 2000 due to widespread vaccination efforts. However, recent years have seen a resurgence of cases, primarily attributed to declining vaccination rates. The Centers for Disease Control and Prevention (CDC) recommends a 95% vaccination rate to maintain herd immunity, but many communities have fallen below this threshold, increasing the risk of outbreaks.

In early January 2025, a collaborative team from Baylor College of Medicine, the University of Texas Health Science Center at Houston, the Houston Health Department, and Rice University detected the measles virus in Houston's wastewater samples before any clinical cases were reported. Utilizing a sequencing-based approach, they identified the virus in samples collected on January 7 from two wastewater treatment plants serving over 218,000 residents. Subsequently, on January 17, two unvaccinated travelers residing in the same area tested positive for measles. This study, published in the American Journal of Public Health, highlights the potential of wastewater surveillance as an early detection system for infectious diseases.

Similarly, in July 2025, Austin Public Health detected traces of the measles virus in wastewater samples from Travis County. Residents were encouraged to ensure their measles, mumps, and rubella (MMR) vaccinations were up to date to prevent potential outbreaks.

These instances underscore the growing role of wastewater surveillance in public health, offering a proactive approach to identifying and mitigating the spread of contagious diseases like measles. By detecting pathogens in wastewater, health officials can gain early insights into community-level infections, potentially before clinical cases are reported. This method allows for timely interventions, such as targeted vaccination campaigns and public health advisories, to prevent widespread outbreaks.

The resurgence of measles cases is closely linked to declining vaccination rates. In Texas, the percentage of children with vaccine exemptions has risen over the last decade, from 0.76% in 2014 to 2.32% in 2023. Gaines County, for example, has one of the highest rates of vaccine exemptions in the state, with nearly 14% of children from kindergarten through grade 12 having an exemption in the 2023-24 school year. This decline in vaccination coverage reduces herd immunity, making communities more susceptible to outbreaks.

In early 2025, Texas experienced significant measles outbreaks. In February, a West Texas county reported 15 cases, primarily among school-aged children, in an area with a high rate of vaccine exemptions. This outbreak resulted in the death of an unvaccinated school-age child, marking the first measles death in the U.S. since 2015. Additionally, in January 2025, two adult cases were reported in Houston, linked to international travel.

In response to these outbreaks and detections, public health officials have emphasized the importance of vaccination. The MMR vaccine is highly effective, with two doses providing 97% protection against measles. Health authorities have urged residents to ensure their vaccinations are up to date, especially in areas where measles has been detected in wastewater. Austin Public Health, for instance, offers the MMR vaccine for uninsured and underinsured residents at its "Shots for Tots and Big Shots" clinics.

The detection of measles in wastewater samples before clinical cases were reported highlights the potential of wastewater surveillance as an early warning system for infectious diseases. Coupled with the concerning trend of declining vaccination rates, these findings underscore the need for robust public health strategies to prevent and control measles outbreaks. Ensuring high vaccination coverage remains a critical component in safeguarding communities against this highly contagious disease.