OTTAWA - Toronto doctors red-flagged Mexico City as a potential incubator of global disease as they put the finishing touches on a report last month that has not yet been released.
The research team led by Dr. Kamran Khan of St. Michael's Hospital cites the teeming metropolis as a biological triple threat: more than 22 million people packed into tight urban areas, lax sanitation, and health gaps that delay disease detection.
Throw in the mighty North American air-travel engine and you have a global launch pad for pathogens.
"Living in an interconnected world is something that benefits us all but there is a certain price to pay as well," Khan said Monday in an interview.
"Essentially, it's vulnerability to global infectious disease threats."
Khan has been hooked on tracking the impact of global flight patterns and disease since SARS arrived in Toronto in 2003 aboard a flight from Hong Kong. The Canadian spread of Severe Acute Respiratory Syndrome ultimately killed 44 people.
"It's been my research interest since SARS to understand the global transportation network because it's what binds the world together," Khan said.
"And we benefit from it tremendously, but it's also this amazing conduit for the spread of infectious disease."
The swine flu virus is suspected in up to 149 deaths in Mexico. Another 1,995 people are in hospital with pneumonia but it's unclear how many of those cases are actually swine flu.
The World Health Organization said Monday that there were 40 confirmed cases in the United States, twice the number previously reported by the Centers for Disease Control and Prevention in Atlanta.
In Canada, a total of six cases had been reported by Monday in British Columbia and Nova Scotia, along with about a dozen suspected but not confirmed cases in Ontario.
Officials have tried to walk a fine line between easing potential panic and warning that the number of infections and deaths will likely rise.
Khan and a team of doctors, statisticians, computer specialists and geographers have worked on what he calls the Bio-Diaspora Project for the last year. Their report - "An Analysis of Canada's Vulnerability to Emerging Infectious Disease Threats Via the Global Airline Transportation Network" - is almost 200 pages.
Its public release was "imminent" pending review by the Public Health Agency of Canada when news broke of the Mexico City swine flu.
The research team examined ticket sale statistics to trace traffic between Canada and an undisclosed shortlist of potential disease-threat locations. Besides Mexico City, Khan would not reveal other cities or regions that were singled out pending the report's release.
He stressed that U.S. airports convey 13 per cent of the world's international air traffic, while Canada handles three per cent - much of it through Pearson International Airport in Toronto.
Passengers travelling between major cities in Asia, Europe and Australia can arrive in Canada on non-stop flights that allow no transit junctures to screen for illness before arrival here.
Still, Khan says the report stresses that infectious disease can't be fought at the border. It recommends that developed countries such as Canada increasingly target international aid at those countries with which close travel links can pose serious threats.
More than a million Canadians travel to Mexico each year, while about 650,000 passengers arrive in Canada from Mexico.
"The future has to be in the international realm," Khan said.
"We can't really think about our countries and focus on domestic aspects of preparedness and response.
"We have to be thinking further upstream about containing threats at their source - before they start to unravel quickly and spread around the globe.
"Even firefighters prefer to prevent fires than to fight them."
