MOUNT CLEMENS, Mich. (AP) — A sampling of sanitary sewage in one southeastern Michigan county has shown an increase in the presence of COVID-19.

Sewage samples pulled from sites across Clinton Township show the rate of actual infection is higher than numbers currently reported by state health officials, the Macomb County Public Works office said Tuesday.

Positive virus tests for Macomb County residents have increased 125% over the past 14 days, the office added.

Macomb County has reported more than 60,000 virus cases and 1,880 deaths since the start of the pandemic.

The state’s COVID-19 cases also have been increasing. Dr. Joneigh Khaldun, Michigan’s chief medical executive, has said Michigan’s case rate spiked 77% over the past four weeks to 172.9 cases per million people.

As of Monday, Michigan had nearly 630,000 cases and more than 15,900 deaths.

“Testing shows the trend line of what’s coming about a week before,” Macomb Public Works Commissioner Candice Miller said. “Unfortunately, our testing is showing that COVID cases will continue to climb into next week.”

Laboratory testing of sewage to detect the coronavirus is considered more accurate in determining overall community infection because it includes sampling of waste shed by individuals who are already infected but who haven’t been tested, Miller’s office said.