Canadian public health authorities say they have identified and contacted 16 of the 28 air travellers in closest contact with a man infected with a dangerous form of tuberculosis.
Officials have been looking for people seated in row 12 on Czech Airlines Flight 0104 to Montreal on May 24, and the two rows ahead and behind the infected man.
In a teleconference Wednesday, Dr. Howard Njoo of the Public Health Agency of Canada said the risk to those 28 people is "low, but we cannot definitively say it's zero."
He took issue with a statement by the airline that it had notified public health authorities upon landing in Montreal.
"The airline will be issuing a correction this afternoon," Njoo said.
However, he couldn't say whether the airline knew it was bringing an infectious person into the country.
"Had we known he was flying in, we could have quarantined him," said federal Health Minister Tony Clement.
The Public Health Agency of Canada is asking any of the 77 passengers who were on the flight to call 1 866 225 0709.
Senior CNN medical correspondent Sanjay Gupta told CTV on that tuberculosis is spread through the air, often by coughing or sneezing.
The man in question didn't appear to have those symptoms and "it appears he has a pretty low likelihood of actually being contagious," Gupta said on Wednesday.
However, he agreed there is still a risk to other passengers.
"The flip side is that he was in an enclosed space for several hours with several other people around him -- that's a very unusual situation. We know tuberculosis rates in prison are higher, for example, because of that close contact, and that's a concern as well.
"I'd be concerned, if I was sitting next to the gentleman, and I'd want to be tested."
Patient speaks
The man, currently in quarantine, told an Atlanta newspaper said he took the first trans-Atlantic flight in order to attend his Greek wedding and honeymoon.
He took the second because he believed his life was at risk.
He is believed to be infected with a form of the disease known as XDR TB, a strain that is considered extremely drug resistant.
He departed Atlanta, Ga. for Paris on May 12 aboard Air France Flight 385, then flew back to North America aboard Czech Air Flight 0104 from Prague, Czech Republic last Thursday, landing in Montreal, then driving to the U.S.
Those who rented him the car told CTV they are wondering about their health risk, although health officials say one would have to be confined with the infected person for a prolonged period to be truly at risk.
The man -- who has not yet been identified -- told the Atlanta Journal-Constitution newspaper that although doctors recommended he postpone his wedding, they didn't order him not to fly. He told the newspaper he knew he had TB, but didn't think he posed a danger to others.
"We headed off to Greece thinking everything's fine," said the man, who declined to be identified in the newspaper because of the stigma attached to his diagnosis.
He also said he returned home via Montreal in order to avoid U.S. authorities. They told him while he was in Italy to turn himself over to officials there due to the seriousness of the disease.
He said he learned his condition was worse than he previously thought, and believed he had to return to the U.S. to get the treatment he needed to survive.
U.S. Centers for Disease Control and Prevention Director Julie Gerberding maintains the man had been advised by public health authorities in Georgia that he should not travel in the first place. It is not clear whether he knew at the time of his departure that he was carrying the XDR-TB strain.
He is being treated at Grady Memorial Hospital in Atlanta, a spokeswoman for the hospital said. He is a resident of Fulton County, Ga.
Infectious disease specialist Dr. Neil Rau said treatment of the drug-resistant form of the disease involves placement in a sanatorium, quarantine and an extensive drug regime.
"And then the other big implication of course is if someone is exposed, you don't know what you can really give them and that's going to be the case on this airplane flight," Rau said Wednesday.
"If someone really is believed to be infected ... you simply have to wait and see whether those people develop the disease and that period could be months, years or decades," he said.
With files from the Associated Press
