The illness, described by manager Ståle Solbakken as a few isolated cases of fever and coughing, had impacted several players including striker Jørgen Strand Larsen and defender Marcus Holmgren Pedersen.
However, medical staff have downplayed the severity, insisting the situation is under complete control.
“Very little fuss considering that we have been close together for almost six weeks,” the team doctor told Norwegian outlet Nettavisen. “We are in control.”
Norway have three days remaining to prepare for the match in Miami, where they will face Thomas Tuchel’s England side.
The Norwegians have emerged as one of the tournament’s surprise packages, having beaten Iraq, Senegal, Ivory Coast and Brazil, with their only defeat coming against France in the group stage.
England, meanwhile, advanced to the quarter-finals following a 3-2 victory over Mexico on Monday and will be looking to continue their title charge.
Norway’s talisman Erling Haaland, who has been in prolific form throughout the tournament, is expected to lead the line as the Scandinavians seek to reach the semi-finals for the first time since 1998.