TRAVERSE CITY — The number of presumed positive COVID-19 cases in Michigan quadrupled Thursday, from 80 to 334.

The surge hails from combining results from commercial and clinical facilities outside the state's single lab — which wasn't previous practice, according to a Michigan Department of Health and Human Services statement.

“We knew there were additional people in Michigan with COVID-19 that had not yet been tested," said Dr. Joneigh Khaldun, chief medical executive and chief deputy for health, who emphasized the need for hygiene and social distancing given the new numbers. 

The jump didn't impact the region's numbers with one case in Leelanau County and one case in Otsego County. 

Grand Traverse County officials said Thursday morning that seven tests submitted from GT County came back negative with many results still pending. They encouraged area residence to practice social distancing, and self-isolate and self-quarantine if they are unsure if they are ill. 

The state laboratory is now getting reports from commercial LabCorp, Quest Diagnostics and clinical labs at Sparrow Hospital, the Beaumont Hospital Network, Henry Ford Health System, the statement said.