"It just so happens that most of the guys that came down with something were guys that were sick," Reds manager Dusty Baker said. "You don't know if they're dehydrated or the severity of it."
Heisey said he felt tightness in his groin as he crossed the plate in the fourth inning. He came to bat again in the fifth, reaching first on a fielder's choice, but was replaced by pitcher Homer Bailey as a pinch-runner. Rookie Kristopher Negron took over Heisey's fielding duties the following inning.
"Groins can be tricky, so they just wanted me to make sure I get the rest of the day and tomorrow," Heisey said. "We'll see how it feels tomorrow. I think, hopefully, I'll be fine. Just a little bit of a tightness thing."
Heisey, who is batting .275 in his 167 at-bats this season, said he has been bothered by his groin off and on all season, but decided to play it safe after feeling the extra tightness Thursday.
"I just felt it a little more than I had," Heisey said. "I think they just wanted to be safe rather than sorry."
With Drew Stubbs out with an injury, there is no true center fielder on the roster if Heisey is unable to play.
Negron, infielder Wilson Valdez and right fielder Jay Bruce have both spent some amount of time in center.
Valdez has made just two appearances in center, as well as three showings in left field, and Bruce played 35 games in center in 2008.
While neither injury Thursday seems to be long-term, Mesoraco downplayed the severity of his damage to a "cramp-type thing" and said the substitution was merely a precaution.
"We'll see how it feels tomorrow and get some treatment," Mesoraco said. "It'll be fine."