Nagin's office said the couple and a security guard were quarantined Sunday as a precaution and were exhibiting no swine flu symptoms.
In an e-mail statement, Nagin spokeswoman Ceeon Quiett said the three are "being treated with utmost courtesy" by Chinese officials.
Nagin "is feeling well and continues to be in communication with his staff," according to Quiett. She did not know how long they would be quarantined.
New Orleans' departing recovery director, Ed Blakely, was a professor at the university and is among the conference's scheduled speakers. He is due to return to the school to become a professor in urban policy after leaving city service this month.
China has been enforcing quarantines and temperature checks at airports throughout the country to prevent the virus from spreading.
The World Health Organization said it has spread to 69 countries and infected nearly 22,000 people. Most of the cases have been mild, although 126 people have died as a result of the disease.
Quiett said a passenger on Nagin's flight to China had "signs and symptoms of an influenza-like illness suspected to be of the H1N1 subtype." People sitting near that passenger on the flight from Newark, N.J., were quarantined. There was no word on what flight it was or how many people were aboard.
Quiett said Nagin and his wife have not been tested for swine flu.
Three other city employees on the trip were not sitting close enough to the passenger to be quarantined, Quiett said. They were the deputy head of the press office, James Ross, city economic development director Ernest Gethers and Lisa Ponce de Leon, director of international affairs.
The mayor and his party were scheduled to return to New Orleans June 15.