TORONTO - It appears no passengers who sat near Andrew Speaker while the American was travelling to or back from Europe last May contracted his multi-drug resistant strain of tuberculosis, international and Canadian officials say.
Authorities from the World Health Organization, the Public Health Agency of Canada and the U.S. and European Centers for Disease Control recently compared notes on followup testing for passengers who shared long-haul flights with the Atlanta lawyer.
A few passengers must still undergo the second test needed to see if they were infected. But most results are in and so far no one who tested negative on the first test went on to show evidence of infection on the followup.
"At the moment there is no conversion that I'm aware of, which means there is no one who has apparently caught TB on the flights,'' Dr. Mario Raviglione, head of the WHO's Stop TB program, said in an interview from Geneva.
Raviglione said his department is planning to hold a meeting within the next couple of months to update WHO's guidelines on handling cases of travel by people infected with tuberculosis to fix shortcomings identified through the Speaker incident.
The Atlanta man flew to Greece via Paris to get married in mid-May, then to Italy on his honeymoon despite having been told he had multi-drug resistant tuberculosis. Public health officials in Atlanta say he was told not to travel, but he and his father -- who taped the conversation -- say he was not ordered not to fly.
While Speaker and his wife were in Rome, officials of the U.S. CDC contacted him to tell him the strain of TB he was infected with was extensively drug resistant -- a diagnosis that was later downgraded back to the multi-drug resistant form. He was instructed not to return to the United States on a commercial flight because to do so would put his fellow passengers at risk.
He and his new wife, the daughter of a CDC TB researcher, bolted. They flew from Rome to Prague and then back to North America via a flight from the Czech capital to Montreal, where they rented a car and drove across the U.S. border.
Public health officials stated they believed the risk of infection for fellow passengers was low, but asked those who sat in the same row as Speaker as well as the two rows in front and behind him on his long-haul flights to get tested for TB. It takes prolonged exposure to become infected with TB, but it's thought that a flight of eight hours or more is sufficiently long to pose some risk.
The U.S. CDC went further, urging all Americans on either flight to undergo testing.
The Public Health Agency of Canada identified and contacted the 29 people who were in that zone of potential infection on the Prague to Montreal flight. All but a few have completed the necessary two tests, an official of the agency confirmed.
"Based on the currently available information, there's no evidence of transmission on the flight,'' said Dr. Tom Wong, director of community acquired infections with the Public Health Agency of Canada.
"That's actually a welcome piece of news.''
Testing after a TB exposure requires an initial or baseline test to establish that a person wasn't already infected with tuberculosis. A followup test a couple of months later establishes whether the immune system had geared up to fight TB. If it has, the person is said to have "converted.''
Raviglione said some of the people tested were positive on the first test, meaning they had already been infected with TB. (The WHO estimates one-third of the world's population is infected and 10 per cent of the infected will go on to develop active disease at some point in their lifetime.)
That complicates the process, because current testing methods cannot detect if any of them might have been re-infected with the MDR-TB strain Speaker carried, Raviglione admitted.
"Overall ... as far as I know there is no new infection that has emerged, although the testing is not definitive,'' he said.
While this is welcome news for Speaker's fellow passengers, it doesn't mean the saga is over, Raviglione said.
He said shortcomings in international guidelines that came to light during the Speaker case are being addressed by a working group. While the main principles -- the guidance on testing people in the two rows on either side of an infected traveller, for instance -- still hold, changes are needed to address actions countries should take when it is evident an infected person may have put others at risk.
"All the basic things will not change. But we want to expand on a few other points, to make it even clearer, if you like, to people what needs to be done in the case of a situation like that one,'' Raviglione said.
"It will define better what the responsibility of the public health authorities is and what WHO is, etc.''
"Mr. Speaker was just the one that sounded, in a way, the alarm of what is going on,'' he added. "Sooner or later there will be a case like that that will fly again and so we have to be ready to try to contain the potential of transmissions to others.''
