Vigilance and preparation are the best ways for the public to respond to the World Health Organization's higher pandemic alert level, an infectious disease specialist says.

Dr. Kamran Khan of St. Michael's Hospital in Toronto leads a research team that is putting the final touches on a report that flagged Mexico City as a potential incubator for global infectious disease threats — given the city's 22 million tightly packed citizens, lax sanitation and gaps in detecting disease.

"Hearing that we've moved to phase five, I can understand and appreciate that may evoke some feelings of anxiety," Khan told CBC Newsworld on Wednesday.

"Really, that anxiety, if it causes panic, is obviously not very productive. We really want to try and channel our energy to being vigilant and prepared for this situation."

The 2003 outbreak of SARS, brought to Canada by a traveller from Hong Kong, killed 44 people in Toronto. Since then, Khan has been interested in how global air travel connects the world, with 3,500 cities with airports moving more than 2 billion passengers a year.

The interconnectedness brings tremendous benefits but also vulnerabilities, according to the doctors, statisticians, computer specialists and geographers who wrote the 200-page report, which will be released by the Public Health Agency of Canada.

"My research really, with a number of scientists around the country, has been looking at thinking a bit more proactively," said Khan. "Thinking about infectious disease threats at their source, and seeing what we can do — perhaps contain threats or mitigate their impacts at their source — this is really the way of the future if we want to prevent threats from becoming international."

In announcing the rise in the pandemic alert level, WHO chief Margaret Chan urged developed countries to provide more money and support for antiviral medications in developing countries, which are likely to be the worst affected.

Khan agreed with Chan, saying the line between international and domestic threats is now blurred.

The report recommends that Canada target international aid to countries with close travel links.

With files from The Canadian Press