But Low insists the symptoms were starting to ease and he expected none of his players to miss out at the Maracana.
"It was the case yesterday that nearly a third of our players were complaining of sore throats," Low said.
"It was a bit of a problem yesterday, but sometimes you have to wait a day to see how it develops. Like Mats Hummels, it was a bit worse on the second and third day, as he had a fever."
Low did not name all the players who had suffered from illness, but Express Sport understands Bastian Schweinsteiger and Sami Khedira were affected along with Hummels.
The Borussia Dortmund defender missed Germany's last-16 match against Algeria on Monday due to a fever.
He said on Wednesday he had recovered and posted a picture of himself sitting on the beach.
The only player to miss training on Wednesday was reserve midfielder Christoph Kramer, who was suffering from a case of the chills.
But he joined his team mates on the pitch yesterday and Low said he expected everyone to play unless they worsened overnight.
"From yesterday to today none of our players have a temperature and all of them could train," Loew added.
"Some of them still have a bit of a cold but it hasn't been the case that they have had any feeling of tiredness.
"I hope they all remain stable until tomorrow and that overnight we don't see any deterioration."
So gut wie wieder hergestellt :)
Almost back at 100% :) pic.twitter.com/Mp1ncU81fw
— Mats Hummels (@matshummels) July 2, 2014
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