Houston sampling wastewater to track spread of COVID-19
By JUAN A. LOZANO
HOUSTON (AP) — Results from a program that’s testing Houston’s wastewater to monitor the local spread of the coronavirus have shown that it could be a faster way of detecting outbreaks in the nation’s fourth-largest city, officials said Thursday.
Since May, the city and scientists from Rice University and Baylor College of Medicine have tested wastewater from the city’s 39 treatment plants. Studies indicate genetic material from the virus can be recovered from the stools of about half of patients with the COVID-19 virus. Wastewater analysis looks for that genetic material.
“The goal is to help develop an early warning system, allowing the health department to identify the city’s COVID-19 hot spots sooner and put measures in place to slow the spread of this disease,” said Mayor Sylvester Turner.
During the summer, Houston had a surge in coronavirus cases as the area’s intensive care units were filled with patients. Since then, hospitalizations have decreased and the city’s positivity rate for the virus has gone from a high of nearly 26% in July to 6.1% as of last week.
Turner has said that while the numbers are better, the city is still reporting positive cases and deaths at levels higher than the spring. Houston has reported 72,196 cases and 1,069 deaths as of Thursday.
Houston is among communities around the world that have implemented wastewater testing programs to help deal with the virus' spread. Colleges across the U.S. are also testing wastewater to detect outbreaks.
The wastewater data can show which parts of Houston have a higher virus load, prompting the health department to sent teams to those areas that can go door to door and inform residents and encourage people to get tested, said Dr. David Persse, Houston’s health authority.
“This will give us that early warning that we may have otherwise missed so we empower people to take care of themselves,” Persse said.
The wastewater testing can also provide a more current view of what’s going on with the virus in the city. The testing is done weekly and the results come back that same week. By comparison, 40% or more of testing data from nasal swabs are more than 2 weeks old, Persse said.
The wastewater data can be used to look at specific locations.
After COVID-19 cases were found at a homeless shelter earlier this year, the city monitored the facility’s wastewater and was able to detect when the virus came back a second time, Persse said.
This isn’t the first time wastewater surveillance has been used in Houston to detect a viral outbreak. In 1962, Joseph Melnick, who worked at Baylor College of Medicine and was a pioneer in polio research, realized polio could be detected in wastewater and started sampling it.
That research prompted Melnick to push for a quicker use of the then-new oral polio vaccine, which helped stop outbreaks of the disease, said Anthony Maresso, an associate professor of molecular virology and microbiology at Baylor College of Medicine.
“So, we can learn from this lesson of history of the importance of doing such measures for public health interventions,” Maresso said.
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