(KHN)Since reopening campus at the University of California-San Diego last summer, university officials have relied on the tried-and-true public health strategies of testing and contact tracing. But they have also added a new tool to their arsenal: excrement.
Sewage is the latest disease detection tool for Covid-19 -- and more
That tool alerted researchers to about 85% of cases in dorms before they were diagnosed, according to a soon-to-be published study, said Rob Knight, a professor of pediatrics and computer science and engineering who helped create the campus's wastewater testing program.
When covid is detected in sewage, students, staffers and faculty members are tested, which has allowed the school to identify and isolate infected individuals who aren't yet showing symptoms — potentially stopping outbreaks in their tracks.
UC-San Diego's testing program is among hundreds of efforts around California and the nation to turn waste into valuable health data. From Fresno, California, to Portland, Maine, universities, communities and businesses are monitoring human excrement for signs of covid.
Researchers have high hopes for this sludgy new data stream, which they say can alert public health officials to trends in infections and doesn't depend on individuals getting tested. And because people excrete virus in feces before they show symptoms, it can serve as an early warning system for outbreaks.
The Centers for Disease Control and Prevention finds the practice so promising that it has created a federal database of wastewater samples, transforming raw data into valuable information for local health departments. The program is essentially creating a public health tool in real time, experts say, one that could have a range of uses beyond the current global pandemic, including tracking other infectious diseases and germs' resistance to antibiotics.
"We think this can really provide valuable data, not just for covid, but for a lot of diseases," said Amy Kirby, a microbiologist leading the CDC effort.
The virus that causes covid infects many types of cells in the body, including those in the respiratory tract and gut. The virus's genetic signature, viral RNA, makes its way into feces, and typically shows up in poop days before symptoms start.
At UC-San Diego and other campuses, researchers take samples flowing from individual buildings, capturing such granular data that they can often deduce the number of infected people living or working there. But in most other settings, due to privacy concerns and resource constraints, testing is done on a much larger scale with the goal of tracking trends over time.
Samples are drawn from wastewater, which is what comes out of our sewer pipes, or sludge, the solids that have settled out of the wastewater. They are typically extracted mechanically or by a human with a dipper on the end of a rod.
When researchers in Davis, California, saw the viral load rise in several neighborhood sewage streams in July, they sent out text-message alerts and hung signs on the doors of 3,000 homes recommending that people get tested.