A team of Michigan State University researchers hopes Detroit sewage will hold clues about the trajectory of COVID-19.
The group has been sampling raw sewage as it arrives at a Great Lakes Water Authority water treatment plant every week since mid-April.
Environmental engineering professor Irene Xagoraraki is leading the effort. She used the same method for a similar project that traced viral outbreaks, including a significant Hepatitis A outbreak, in Detroit several years ago.
“We put everything together, and we were able to see the spikes in Hepatitis A seven to nine days prior to the time they showed up in the clinical data,” Xagoraraki said. “So based on those results, we thought we could do something similar with COVID-19.”
Xagoraraki said the research could give us an early glimpse of when COVID-19 infections might start to spike again.
“I hope there’s not going to be a second wave, that’s my hope, but if there is, my hope is that we can capture an early signal and warning, so that we can take action,” she said.
And since we can’t test everyone for COVID-19, finding the virus in human waste can also give us a better indicator of how much the virus has actually spread through the community, according to Xagoraraki.
“Taking a community sample is going to give us information that we wouldn’t otherwise be able to obtain,” she said.
Although Xagoraraki said her team has already found COVID-19 in the samples it’s collected, finding the virus in wastewater is not a simple process.
Xagoraraki told MSU Today that her team has developed two models. A viral identification model, or Viral-ID, determines diversity and genetic makeup of viral infections in a certain population at a particular point in time. The second, a viral prediction model, or Viral-PD, provides early signals of fluctuations of target viral diseases, such as COVID-19, in certain areas over time.
Using those models, Xagoraraki said her team can both verify that wastewater samples contain the virus, and trace them back to a specific population. But that process is also complex. Finding the virus first requires concentrating and cleaning a sample to remove chemical or microbial contamination. Then they need to take into account the sewer system’s geography and hydrology, look for certain biomarkers, determine rates of viral shedding, and take into account issues like dilution.
Nonetheless, Xagoraraki said the team should be able to publish some preliminary data as early as next month.
“So far, we've seen some differences between the [different sewer] interceptors, which tells us that there are differences in the number of cases in the different counties,” she said. “We're currently analyzing the data in more detail, and we're logging them into our model to make those connections.”
The current project is funded by the Great Lakes Water Authority, and is done in collaboration with the Detroit Water and Sewerage Department. It’s scheduled to continue for more than two years.