The mayor, his wife and a member of the mayor's protection unit are under quarantine in Shanghai. The mayor's office says everyone is being treated with the utmost courtesy.
Other passengers who were sitting near the passenger showing flu-like symptoms are also under quarantine.
The mayor's staff doesn't know how long the quarantine will last; that decision is up to public health officials in China.
Mayor Nagin was supposed to fly to Sydney, Australia to give a speech, but for now, that trip is on hold.