CHAPEL HILL, N.C. (WNCN) – Scientists who monitor wastewater for COVID-19 levels said signs point to a surge.

North Carolina released numbers showing a 55 percent increase in virus particles in the wastewater since last week.

Dr. Rachel Noble and her team of researchers at UNC measure COVID-19 levels in wastewater from treatment plants across the state.

“Those sewage treatment plants receive waste from the entire community, so they take a sample that’s basically representative of a 24 hour window,” Noble said, adding that wastewater can often pick up COVID-19 cases before people feel sick. “Whenever you become infected, pretty much as soon as your body starts manufacturing the virus, but before you yourself feel any symptoms, you’re already shedding the virus.”

Back in the spring, some places in the state reported no COVID-19 particles in wastewater at all, but that didn’t last long.

Lately, Dr. Noble said the numbers are heading in the wrong direction.

“The sites that look like they’re red dots are some of the highest concentrations of the virus since we started monitoring over the course of the pandemic,” she said, referring to the state health department’s wastewater monitoring map. “That means we’re in a peak, rather than a valley.”

She said wastewater monitoring is becoming more important in determining COVID-19 trends because most people who have the virus now test at home and never report their results to the state.

“You can actually really see, even though we have a lot of virus in the wastewater which means a lot of infected people, we don’t have a lot of people going and getting tested,” Noble said.

If people want to avoid getting the virus, she said looking at wastewater numbers can help gauge risks.

Noble said wastewater numbers are one of the best ways we currently have to measure COVID-19 trends, but there are limits.

Currently, scientists can’t monitor areas that are served by septic systems, and numbers take about one week to turn around.

Noble said her lab gets most of the samples on Wednesday mornings, analyzes them and sends the information to the state. They’re published the following Wednesday.

Still, she said that’s a pretty quick turnaround and can give people a good idea of the trends.