After a weekend of growing concern that there might be a coronavirus outbreak in their clubhouse, the Cardinals learned Monday that nearly a fourth of their roster has tested positive for COVID-19.

The Cardinals have 13 confirmed positive COVID-19 tests in their traveling party. Of those 13, seven are players and six are staff members. As a result, Major League Baseball has postponed this week’s series in Detroit against the Tigers, which was already moved back and rearranged after positive tests postponed the Cardinals’ series in Milwaukee.

Eight of the 13 are experiencing some mild symptoms of the virus, ranging from headaches to low-grade fevers, but none have been hospitalized. The symptoms began after the positive tests, president of baseball operations John Mozeliak said Monday. The other five are asymptomatic. All 13 members of the organization who tested positive have left Milwaukee via car and returned to their homes.

The rest of the team remains in Milwaukee and must go two days with negative tests to be cleared to travel. The Cardinals hope to be able to travel Wednesday morning by plane to have a light workout at Busch Stadium that afternoon. Then they hope to resume their schedule by playing the Cubs on Friday in St. Louis.

For now, the 44 remaining players and staff in Milwaukee are quarantining in their hotel rooms for the fourth straight day and will continue to be tested daily, which has happened ever since the Cardinals learned of two initial positive tests late Thursday night. While the Cardinals utilized rapid testing at a Milwaukee hospital the first few days, they’ve moved exclusively to using MLB’s saliva tests for results.

With testing and continued isolation, the Cardinals are hopeful they have contained the outbreak.

“We all hear about flattening the curve and what it means in our country, in our states and our cities, but looking at it from a baseball team standpoint, it’s a microcosm,” Mozeliak, who is in Milwaukee with the team, said on a Zoom call with reporters. “We are not there yet, but we are getting closer. And that’s why we will remain in self-isolation.”

The 13 individuals who tested positive have not given consent to disclose their identities, citing medical privacy. Mozeliak said the team doesn’t have a concrete answer to where the first person infected got the virus but is confident that it originated in St. Louis, not on the road. The Cardinals left for Minnesota on Monday evening, and the first two positive cases were discovered via testing conducted on Wednesday before the Cardinals’ game against the Twins.

Mozeliak said the Cardinals will likely review their health and safety protocols for home and the road, but he cited the challenges of playing baseball in a pandemic.

“In fairness, you’re in a pandemic,” Mozeliak said. “It’s almost impossible to say that we can build a dome around ourselves and move from city to city, move from our home to the ballpark. … The point is anything can happen. We tried to put things in place that would prevent this from happening, but it just shows you how challenging that is.”

Mozeliak later added, “I don’t think there’s anything we could have done differently on the road. I’m very confident that this originated in St. Louis, and the timing of the tests dictated that we happened to be on the road. I don’t know what we could do differently other than not put somebody that’s infected on our plane.”

The Cardinals began contact tracing immediately after learning of the two initial positive tests, so the team was somewhat aware of who was likely to test positive over the next few days. But Mozeliak said the virus spread quicker than he originally thought it would, considering how quickly the Cardinals self-isolated and began testing.

The roster will look significantly different when the Cardinals play again. Seven players will likely have to be replaced, although the roster sizes are currently set to shrink from 30 to 28 on Thursday. The replacement players and staff will come from the team’s alternate training site in Springfield, Mo. Mozeliak said he doesn’t expect for now that the team will add to its 60-man player pool. The Cardinals haven’t had any players approach club leadership about electing not to play this season, Mozeliak said.

Every individual who tested positive will go seven days before being tested again, Mozeliak said. Then, the individual must have two negative tests at least 24 hours apart. The individual must be symptom-free and go at least 72 hours without a fever.

“Overall, I think we can withstand this,” Mozeliak said. “A lot of it’s going to be how long does it take for someone to return. These are all unknowns. It’s not like a sprained ankle where you might have an idea when someone’s coming back.”

The Cardinals will have seven games to make up in an already shortened and condensed season. Acknowledging the challenges that will come with the rescheduling, Mozeliak is hopeful it can be done starting Friday -- nine days after the Cardinals last played a game -- against the Cubs.

“Haven’t really even thought about our schedule much other than hopefully playing Friday,” Mozeliak said. “It’s hard to think about the future when you’re literally just trying to get through the day.”