Because SARS-CoV-2, the novel coronavirus that causes COVID-19, has been found in the feces of confirmed COVID-19 patients, wastewater-based epidemiology might be an effective way to track the extent of the disease in a population.
Wastewater epidemiology is most commonly used to monitor drug usage in a community. It can also provide information about the spread of infection when individual tests are limited. A team led by Eric J. Alm of the Massachusetts Institute of Technology and Biobot Analytics has now used quantitative reverse transcription polymerase chain reaction (RT-PCR) to measure SARS-CoV-2 in sewage from a wastewater treatment facility in Massachusetts. The researchers published their findings on the preprint server medRxiv, so the study has not yet been peer reviewed (medRxiv 2020, DOI: 10.1101/2020.04.05.20051540).
The Biobot team analyzed four samples taken before the first known US case of COVID-19, and all tested negative for the virus. All 10 samples taken between March 18 and March 25 tested positive for SARS-CoV-2, at levels higher than the researchers expected based on the number of confirmed cases. They used direct DNA sequencing to verify that the RT-PCR products were actually from SARS-CoV-2. But more information is needed, such as the amount of virus in stool from positive patients over the course of the disease, to fully interpret the findings.
Wastewater analysis “could be used to establish whether COVID-19 has infected a community and monitor for when the community is relatively free of COVID-19,” says Kevin Thomas, an epidemiologist at the University of Queensland. The approach should be used in combination with individual testing, he says.
Biobot is now getting weekly samples from more than 100 treatment plants around the US, according to Mariana Matus, Biobot’s CEO.
This story was updated on April 20, 2020, to clarify that the results presented were published on a preprint server and therefore not yet peer reviewed.