Phoenix: An outbreak of illness in a major league clubhouse looks something like this:

Dodgers pitcher Brock Stewart wore a surgical mask as he walked to his locker at Camelback Ranch. A quartet of air filtration devices designed to prevent the spread of germs lined the room. Strength and conditioning coach Brandon McDaniel administered vitamins to the healthy. Matt Kemp exaggerated a cough as he staggered to his locker.

“If you’re sick, go home,” closer Kenley Jansen said. There wasn’t much of an audience for his message. The clubhouse was mostly empty. The Dodgers were either eating breakfast or lifting weights or huddling in a quarantine or not even in the building.

A virus causing chills, fatigue and other flu-like symptoms overtook the Dodgers on Wednesday. The number of affected totalled 24 or 25, manager Dave Roberts said. The team sent the ill home. The medical staff hoped the symptoms would subside in one to three days, Roberts said.

“I haven’t seen anything like this,” Roberts said.

The illness caused widespread changes to Roberts’ line-up for Wednesday’s game against San Diego. Hyun-jin Ryu was scratched from his start and replaced by Wilmer Font. The list of affected position players was extensive: Cody Bellinger, Yasiel Puig, Austin Barnes, Logan Forsythe, Enrique Hernandez, Kyle Farmer and Trayce Thompson were all listed on the initial travel roster, but weren’t included in the line-up.

Josh Fields was slated to pitch a session of live batting practice with Rich Hill. Instead, the Dodgers sent Fields home. Hill reported no symptoms — although the team did place a filtration system next to his locker. Alex Wood joked the device was necessary to protect Hill, who at 38 is the second-oldest player on the roster.

Hill left the clubhouse in the morning to throw a session of live batting practice on a field on the minor-league side of the complex. After three innings, Hill returned to find the machine roaring as he spoke to a few reporters. “Very loud,” Hill said.

The coaches and support staff were not immune. Roberts took his coaching staff to dinner on Tuesday night. Nothing felt amiss, he said. The next morning, first-base coach George Lombard and several members of the training staff turned up sick. Danny Lehmann, an assistant coach who handles game planning, replaced Lombard.

“We’re short-handed a little bit,” Roberts said.

Roberts cobbled together a line-up to face the Padres. Joc Pederson and Andrew Toles started in the outfield. Chris Taylor played shortstop. A day after catching, Yasmani Grandal served as the designated hitter. Max Muncy started at third base. The other four starters — Tim Locastro, Henry Ramos, Will Smith and Edwin Rios — had combined for one major-league at-bat, which Locastro took during the final weekend of the 2017 season.

The Dodgers had not yet determined where the virus began. Corey Seager dealt with food poisoning last week, but that appears unrelated to the current situation. Roberts hoped for more clarity in the coming days.

“We’re trying to get to the bottom of it,” Roberts said.

Hill goes long

The pitchers in the Dodgers starting rotation have gone one or two innings in their first outings this spring. Clayton Kershaw threw one inning. So did Alex Wood. Kenta Maeda threw two.

Hill opted for three innings, albeit in the controlled environment of live batting practice on a minor-league field. Asked if the extra work was related to Hill’s zeal for building up calluses to prevent blisters, Hill shrugged.

“It was just me-related,” Hill said. “You have to build up. This was the first time I’ve gotten up three times since last year. And the next outing, I’d like to be ready to go, three, maybe four innings.”

Hill indicated he would make his next appearance in a major-league game. He spent a significant portion of spring training in 2017, his first as a Dodger, pitching in minor-league settings. Hill allowed 27 runs in 28 Cactus League innings during the past two springs.

“It’s efficient, being able to have a controlled environment in the beginning,” Hill said. “Where you can experiment a little bit more, and stuff like that. I don’t really like going out to games and experimenting with pitches, when you’re trying to compete and get guys out.”