The other chimps had been under quarantine but are now back on public display in the ape house environment.
"It doesn't pose any further risk to our animals. They are recovering and as you can see behind you, they're doing pretty well...it takes a long time to recover from this. Like in humans when you get a respiratory disease," said Steven Thompson, Lincoln Park Zoo senior vice president.
This virus causes at least 15 percent of the common colds suffered by humans worldwide every year.
Thompson says how the chimps contracted the virus is a question that probably will never be answered.