as Hendra and Ebola, visit us only occasionally and, when it happens, arrive soon at dead ends. Others do as the influenzas and the HIVs have done—take hold, spread from person to person, and achieve vast, far-flung, enduring success within the universe of habitat that is us. Plasmodium falciparum and Plasmodium vivax, from their origins in nonhuman primates, have done that also.
Plasmodium knowlesi may be at a transitional stage—or anyway, a straddling stage—and we can’t know its future plans. It’s a protist, after all; it doesn’t have plans. It will simply react to circumstances. Possibly it will adapt to the changing trend among primate hosts—fewer monkeys, more humans—as its plasmodium cousins have adapted over the epochs. Meanwhile it serves as a nice reminder of what’s crucial about any zoonosis: not just where the thing comes from but how far it goes.
IV
DINNER AT THE RAT FARM
32
In late February 2003, SARS got on a plane in Hong Kong and went to Toronto.
Its arrival in Canada was unheralded but then, within days, it began to make itself felt. It killed the seventy-eight-year-old grandmother who had carried it into the country, killed her grown son a week later, and spread through the hospital where the son had received treatment. Rather quickly it infected several hundred other Toronto residents, of whom thirty-one eventually died. One of the infected was a forty-six-year-old Filipino woman, working in Ontario as a nursing attendant, who flew home to the Philippines for an Easter visit, started feeling sick the day after arrival (but remained active, shopping and visiting relatives), and began a new chain of infections on the island of Luzon. So SARS had gone halfway around the world and back, in two airline leaps, over the course of six weeks. If circumstances had been different—less delay on the ground in Toronto, an earlier visitor headed from there to Luzon or Singapore or Sydney—the disease could have completed its global circuit far more quickly.
To say that “SARS got on a plane,” of course, is to commit metonymy and personification, both of which are forbidden to the authors of scientific journal articles but permissible to the likes of me. And you know what I mean: that what actually boarded an airplane in each of those cases was an unfortunate woman carrying some sort of infectious agent. The seventy-eight-year-old Toronto grandmother and the younger nursing attendant remain anonymous in the official reports, identified only by age, gender, profession, and initials (like BW the malarious surveyor), for reasons of medical privacy. As for the agent—it wasn’t identified and named until weeks after the outbreak began. No one could be sure, at that early stage, whether it was a virus, a bacterium, or something else.
In the meantime it had also arrived in Singapore, Vietnam, Thailand, Taiwan, and Beijing. Singapore became another epicenter. In Hanoi, a Chinese American businessman who brought his infection from Hong Kong became ill enough to merit examination by Dr. Carlo Urbani, an Italian parasitologist and communicable-diseases expert stationed there for the World Health Organization. Within ten days the businessman was dead; within a month, Dr. Urbani was too. Urbani died at a hospital in Bangkok, having flown over for a parasitology conference in which he was never able to take part. His death, because of his much-admired work within WHO, became a signal instance of what emerged as a larger pattern: high rates of infection, and high lethality, among medical professionals exposed to this new disease, which seemed to flourish in hospitals and leap through the sky.
It reached Beijing by at least two modes of transport, one of which was China Airlines flight 112, from Hong Kong, on March 15. (The other route into Beijing was by car, when a sick woman drove up from Shanxi province seeking better treatment in the national capital; how she had become infected, and whom she infected in turn, is a different branch of the story.) Flight CA112 took off from Hong Kong that day carrying 120 people, including a feverish man with a worsening cough. By the time it landed in Beijing, three hours later, twenty-two other passengers and two crewmembers had received infectious doses of the coughing man’s germs. From them it spread through more than seventy hospitals just in Beijing—yes, seventy—infecting almost four hundred health-care workers as well as other patients and their visitors.
Around the same time, officials at WHO headquarters in Geneva issued a global alert about these cases of unusual pulmonary illness in Vietnam and China. (Canada and the