{"id":1249,"date":"2021-11-09T12:15:13","date_gmt":"2021-11-09T19:15:13","guid":{"rendered":"https:\/\/knightlab.ucsd.edu\/wordpress\/?p=1249"},"modified":"2025-08-01T09:37:29","modified_gmt":"2025-08-01T16:37:29","slug":"the-proof-is-in-the-poop","status":"publish","type":"post","link":"https:\/\/knightlab.ucsd.edu\/?p=1249","title":{"rendered":"The Proof is in the Poop"},"content":{"rendered":"

When early evidence emerged that people with COVID-19\u2014whether or not they have symptoms\u2014shed the virus in their stool, \u201cthe sewer seemed like the \u2018happening\u2019 place to look for it,\u201d said Smruthi Karthikeyan, an environmental engineer and postdoctoral researcher who works in the lab of Rob Knight at UC San Diego School of Medicine.<\/span><\/a><\/span><\/p>\n

Researchers in Knight\u2019s lab are used to getting their hands dirty. The team has long been known for their studies of the gut microbiome\u2014the unique communities of microbes that live in our gastrointestinal tracts. People all over the world participate in their research program, The Microsetta Initiative (aptly abbreviated \u201cTMI\u201d), by mailing their fecal swabs to Knight\u2019s lab. The crowdsourced project has allowed the team to study the many factors that might influence the makeup of a person\u2019s gut microbiome, and the many ways it influences our health.<\/span><\/p>\n

\"\"<\/a>
<\/span> Smruthi Karthikeyan (left) and Rob Knight (right) pick up wastewater samples from collection robots on the UC San Diego campus.<\/em><\/span><\/figcaption><\/figure>\n

By the summer of 2020, Karthikeyan, Knight and team were sifting through fecal samples closer to home \u2014sewage flushed away by people occupying UC San Diego buildings\u2014to look for the virus that causes COVID-19.<\/span><\/p>\n

Just one month after their wastewater detection system came online, the team detected a positive case in the Revelle College area on the Friday afternoon before the Labor Day weekend.<\/span><\/p>\n

\u201cAt the time, we had just three wastewater samplers around campus, two by the hospital, which of course will be positive due to the patients being treated there, and one negative control by Revelle College,\u201d Karthikeyan said. \u201cIt was business as usual and I packed up to leave the lab for the day when I saw that the Revelle sample was actually positive! I re-ran it multiple times for sanity\u2014all came back positive. That launched a thousand ships and put the whole surveillance team on overdrive.\u201d<\/span><\/p>\n

The campus community was notified within 14 hours and targeted messages were sent to people associated with the affected buildings, recommending they be tested for the virus as soon as possible. More than 650 people were tested for COVID-19 that weekend. As a result, two asymptomatic individuals were diagnosed with COVID-19, and they self-isolated before an outbreak could occur.<\/span><\/p>\n

Now, Knight, Karthikeyan and team monitor wastewater from 350 UC San Diego buildings daily. Notifications are automatically sent to affected buildings, results are available on a public dashboard and positive samples are being sequenced to track the emergence of new coronavirus variants.<\/span><\/p>\n