THE THIN WHITE LINE: the history of a future avian influenza pandemic

Chapter 1: Outbreak

The pandemic superhighway

    On October 14, two men boarded commercial airplanes in China and joined the daily flow of human traffic between the Far East and Canada.
    Air travel has made the increasingly globalized world a much smaller place by 2012. More than 1.4 billion flew commercial planes in 2011; 25 people crossed international borders every second. More than 110 million entered Canada by land, sea and air. Canadians took more than 700,000 trips to Asia, while Asians took more than 1 million trips to Canada. Americans, meanwhile, took 34.6 million trips to Canada.
    These travel routes formed highways for infectious disease. With air travel, a new strain of pandemic influenza could reach Canada within weeks of an outbreak occurring almost anywhere in the world, and circle the globe within months.
    Both men were successful Canadian businessmen traveling alone.
    Tom Woo, an independent business consultant, boarded a commercial plane at Hong Kong International Airport. Born in China, a naturalized Canadian citizen for the past 10 years, and fluent in Mandarin and English, he had built a successful consulting practice based on helping Canadian companies navigate the intricacies of doing business in Hong Kong, Taiwan and the People’s Republic of China.
    The plane left the runway and began its 14-hour flight to Vancouver International Airport, where Woo planned to change planes and continue on to Calgary, Alberta to meet with a client, the senior management team of a technology company.
    Sitting in business class at 30,000 feet over the Pacific, he slept.
    Several hours later, John Warren, vice president of a Canadian tourism operator, boarded a plane at Shanghai Pudong International Airport. Warren’s company, which operated hotels and visitor centers throughout western Canada, had sent him to Shanghai to build relationships with key officials and promote Canada as a destination, particularly the company’s new, highly profitable eco-tour packages. China had become a key growth market for Warren’s company; travelers from China and Hong Kong had made some 225,000 trips to Canada the previous year, spending about $370 million.
    Canada’s tourism industry had recovered after the SARS outbreak in Toronto seven years before with its associated media coverage and WHO advisory against travel. Thousands of jobs and billions in revenues had been lost because about 800 people died due to a new respiratory disease. Over the years, travel numbers had recovered, particularly between Canada and Asia. Warren wanted his firm to aggressively promote growth in this market.
    A secondary objective of his trip had been highly successful; a Shanghai-based tour operator signed a memorandum of understanding to market his firm’s tourism products to consumers throughout southern China. But the day before he received a call from his office and learned that the WHO had slapped a new strongly worded travel advisory on Vietnam for a suspected Avian Flu outbreak, which would likely result in new losses for the world’s tourism industry, not to mention jeopardize his firm’s China expansion plans if the WHO next set its sights on that country. He must have felt discouraged at winning a battle but facing the prospect of losing the war again.
    The plane began its 9.5-hour flight to Vancouver without delay. There, Warren would promptly board his connecting flight to Calgary for the 2012 Alberta Travel & Tourism Industry Conference.
    Woo and Warren did not know this, but they were scheduled to take the same connecting flight to Calgary.
    There were also both carriers of influenza.

    Canada had prepared. In response to the WHO travel advisory concerning Vietnam, Canada immediately shored up its defenses at 14 airports that received travelers from the Far East as well as 18 land border crossings between Canada and the United States. By October 14, three lines of defense had been constructed against a traveler bringing novel influenza or any other flu-like pathogen into the country.
    The flight attendants on Cathay Pacific’s planes had been trained to be vigilant for passengers with flu symptoms. If somebody exhibited symptoms, the plane had to radio ahead to the airport for inspection by quarantine officers. Woo had begun to show symptoms, but slept during most of the flight. Warren had not yet begun to show symptoms. Neither attracted any particular attention.
    As their planes landed in Vancouver, the men encountered the beginnings of the second line of defense. The flight attendants passed out yellow cards. These cards listed symptoms of SARS and influenza, and asked if the passenger had a fever or any other symptoms or had been in contact with a person with these symptoms within the past 10 days.
    If the two men answered yes to any of these questions, they would be examined by a screening nurse at the airport. Depending on the results, airport authorities might quarantine the entire planeload of passengers for up to two weeks.
    Woo did not tell the whole truth on his yellow card. He had begun to show at least some symptoms of influenza, including fever. However, he may have believed he had a simple head cold. Certainly, he did not suspect that he could be a carrier of pandemic influenza. It’s likely he would have considered even the possibility to be outrageous. During his stay in Hong Kong, a bad flu was going around, but it is probable that nobody said anything specifically about bird flu.
    The men deplaned and joined the flow of passengers heading towards customs. Suddenly, signs instructed passengers to go single file.
    They had gotten through two lines of defense, and now they approached the third: thermal image sensors. Canada had installed these infrared cameras at eight major airports in Canada as a method of flagging passengers running a fever by detecting differentials in infrared energy, or heat.
    The cameras imaged Woo and Warren as they passed them. The backgrounds of the respective images, with a lower temperature, appeared black. The men, with a higher temperature, appeared white. Body areas with temperatures above 38ºC, indicative of fever, were supposed to be rendered in red.
    Although Woo was running a fever at this point, the camera did not flag him.
    Thermal image sensors operated at a distance, without contact, limiting health risk for the screening agent, and only took one to two seconds to display temperature compared to 30 seconds using a thermometer.     The cameras only measured body surface temperature, however, not core body temperature, and skin is typically two to three degrees cooler than the body itself——a margin of error that can be exacerbated by constant slight changes in environmental conditions such as background heat.
    Woo walked past the camera, his skin temperature within the margin of error.(10) He entered the airport. From here, he could travel anywhere within Canada with ease. He left traces of virus on surfaces and objects he touched.
    Under the right conditions, influenza virus can live, and stay infectious, outside the human body for days. In this way, the flu can indirectly infect people. Most of the contagion, however, he passed through the air, by coughing or sneezing, directly infecting people within six feet of him who unluckily breathed just one of the virions ejected from his respiratory tract. Each sneeze blew out a cloud of a hundred thousand virions. This is how most people get the flu——directly, by breathing virus into the lungs.
    Meanwhile, Warren passed through customs, retrieved his bags, and decided to have a quick drink at an airport bar before boarding his connecting flight to Calgary.
    Then Woo got into line at customs. Leslie McKay, a customs agent, questioned him. She took his passport, welcomed him home, asked him where he had come from, and then asked if he had brought anything back with him.
    At this point, as if confessing, Woo coughed explosively, his face flushed.
    McKay asked him to confirm the responses on his yellow card. Woo told her he had a bad cold and that he would take care of it once he had a chance to buy some medicine. McKay, having been properly trained for how to act during a pandemic alert, called for a quarantine officer.