(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.

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.