Leake felt he would be ready to start on Thursday. He was given IV fluids on Tuesday night and planned to get another one later on Wednesday.
"I was pretty dehydrated," Leake said. "I just watched TV, watched the game. That's about all I could do."
If Leake won't be ready to start on Thursday, Reds manager Dusty Baker indicated that someone from the bullpen could step up and take Leake's turn. Another likely scenario is that Friday starter Bronson Arroyo could move up a day to pitch.
Shortstop Zack Cozart, who was also affected by illness, did not start a second straight game on Wednesday as Wilson Valdez started in his place. Cozart felt like he was available to come off of the bench and expected to start on Thursday.
"I only lost a couple of pounds," Cozart said. "That was good. I drank a lot of fluids today. That's all I've been doing, drinking water and Powerade stuff."
Besides Leake and Cozart, Drew Stubbs, Logan Ondrusek, Devin Mesoraco were ailing and unavailable on Tuesday. While getting a 7-1 win over the Indians, Baker had only a two-man bench in Miguel Cairo and Kristopher Negron.
Joey Votto, who hit a two-run homer and a RBI single in Tuesday's win, was also under the weather, but downplayed its effect on him.
"I didn't think I was in a place where I needed to sit," Votto said. "Other guys were throwing up, had IV's, but I wasn't in that place. I was sick, but I could play through it, that's it."
While there are some theories, the club still doesn't know how so many players got sick at one time.
"It only takes one carrier," Baker said. "A lot of them were shaking hands and stuff [Tuesday] too with people. It's hard to put a handle on it. Now it's not a matter of the problem, it's a matter of the solution to the problem. It's too late, the problem is already here."