Sewers provide solutions to public health data gaps

Tracking down the source of a disease outbreak is often challenging, requiring a laborious combination of in-person detective work, laboratory analyses and data crunching. The approach hasn’t changed that much since 1854, when physician John Snow identified the source of a cholera outbreak in London by interviewing residents and mapping out where the infected people lived.

Surely there must be another way. There is, and it lies right beneath our feet. Researchers are increasingly turning to wastewater in municipal sewer systems as an efficient, effective way to monitor a community’s health and spot outbreaks early on.

The coronavirus pandemic has vastly accelerated the use of wastewater testing for disease surveillance, freelance science writer Betsy Ladyzhets reports in this issue. In the early days of the pandemic, scientists were desperately looking for a way to track the virus’s movements. They knew that sewage testing was effective in identifying diseases spread through fecal matter but didn’t know if SARS-CoV-2, the virus that causes COVID-19, would show up. Researchers in the San Francisco Bay area gathered sewage samples and compared the data with reported cases. They matched.

Since then, there’s been an explosion of interest in the use of wastewater testing to track COVID-19, a data source that has become increasingly important as people rely more on at-home tests that aren’t reported to public health agencies. Scientists have also tested wastewater to track the emergence of mpox in the United States (it worked) and are investigating whether sewage surveillance might be useful in guiding public health decisions on a host of other infectious diseases, from chicken pox to Lyme disease.

Fans of public health history will know that sewers have played a starring role in infectious disease management for centuries. The Romans, for example, started building sewers in the sixth century B.C., mainly to drain swamps and remove floodwaters. By the 19th century, urban areas in Europe and the United States had grown to the point where they were struggling to efficiently remove human waste without further contaminating the rivers and wells that provided drinking water. Civil engineering became a science, and London, Paris, Chicago and other cities invested vast sums in building sewer systems. Many of those systems remain in use today.

In a recent episode of Ted Lasso, the fish-out-of-water American coach takes his floundering English soccer team on a tour of London’s Victorian-era sewers. A discussion ensues underground on the Great Stink of 1858, during which the scent of the sewage-clogged Thames became so rank that politicians in the new Parliament building allocated 3 million pounds to building a sewer system.

Coach Ted uses the sewers of London as a metaphor to help his players manage external criticism and internal self-doubt: Stink happens, you gotta let it flow and get on with your business. That metaphor may be a wee bit strained, but I relished seeing a great moment in municipal sanitation history get its due. And I’m glad that we can update you on the latest scientific efforts in using stinky sewers to fight disease.

Nancy Shute is editor in chief of Science News Media Group. Previously, she was an editor at NPR and US News & World Report, and a contributor to National Geographic and Scientific American. She is a past president of the National Association of Science Writers.