Death by sneezing

As the U.S. hunts for germ weapons in Iraq, world health officials scramble to stop a fatal mystery disease that spreads like the common cold.

By Arthur Allen

Apr 2, 2003 | Ever since AIDS began its terrifying spread, scientists who track emerging infections have been warning about the potential for another global outbreak, something that might resemble the Great Influenza Pandemic of 1918, which ultimately killed 50 million people. The latest news of quarantines and deaths due to a highly contagious mystery virus -- from Hong Kong, China, and Vietnam, as well as Canada and the United States -- could be a frightening picture of the start of such a natural disaster. As the U.S. government hunts for germ weapons in Iraq, while urging American doctors to vaccinate 10 million people against the long-vanquished smallpox virus on the tiny chance that terrorists might get hold of it, U.S. public health officials have been working hard with their colleagues abroad to get a handle on severe acute respiratory syndrome, or SARS.

Nature, in all its whimsy, has thrown us a big, fat, ugly curve -- a virus with a harmless background that suddenly turned lethal.

In Hong Kong this week, hundreds of contaminated people were rounded up and bused to quarantine camps. In Singapore, schools were closed and nurses were posted at the airport to ferret out sickly-looking arrivals. In Toronto, two hospitals stopped their admissions to avoid spreading the disease. And in San Jose, Calif, an American Airlines flight from Tokyo was held on the ground until five crew members and passengers reporting SARS symptoms could be removed to a hospital and everyone else on the plane could be briefed about how to monitor themselves for signs of the illness. Those hospitalized were later declared disease-free. But clearly the newly identified disease is raising the public's anxiety level.

One virologist, who wished to remain anonymous, described the potential, in a worst-case scenario, for "total panic."

Researchers scrambling to identify the cause of SARS believe it may result from the genetic mixture of two strains of a previously innocuous organism called the coronavirus, or possibly of a coronavirus and another bug. This chance recombination might have occurred inside a mouse, a chicken or a pig before the virus jumped to humans.

Human coronavirus infections -- responsible for about a quarter of all common colds -- are usually so mild that no one has ever tried to make a vaccine to prevent them or a drug to treat them. That's no one's fault, considering the seemingly limited threat posed by the infections, but it puts the world at a disadvantage. While intensive care can keep most SARS patients alive, there are no drugs designed to combat the infection.

"In terms of antivirals and vaccines, we are way behind," says Ken McIntosh, a Harvard microbiologist who helped discover coronaviruses back in 1965. Like other virologists, he is not necessarily surprised by the evidence that this virus family has given birth to a killer; coronaviruses mutate easily, and are notoriously free and easy with their genetic material.

"I always thought something like this would happen. It was just a matter of time," says Pierre Talbot, a coronavirus expert and chief of the Armand-Frappier Institute, a public health research center at University of Quebec.

But hypotheticals do not translate into research grants, and Talbot's lab is one of only a handful in the world working with coronavirus. "It's not HIV," he says. "It's not a very popular field."

"No one thought [coronaviruses] were very important," adds Stan Perlman, a virologist at the University of Iowa.

Until now, of course.

So far, SARS has infected more than 1,800 people in 13 countries, killing 62 of them, in the past few months. Most of the infections have hit middle-aged to elderly people, though in one reported case, the virus was identified in a 1-year-old child adopted from China and brought to Massachusetts. The initial symptoms -- fever, chills, dry cough -- are like common upper respiratory ailments, but this bug is capable of overwhelming the immune system. About 10 percent of SARS infections lead to severe breathlessness, oxygen depletion and organ failure, and about a third of the severe cases die -- particularly old patients and those with existing medical problems.

Up to now, SARS has had a fatality rate of about 3.5 percent. If that sounds mild compared, say, to the virus that causes AIDS, consider this: The pandemic flu of 1918 killed "only" about 2.5 percent of those whom it infected. That amounted to 50 million people worldwide.

SARS is not the first scary microbe to emerge in the era of globalization, but it could be the one most likely to spread. Ebola killed its hosts too quickly to get out of Africa. Hantavirus and Nipah, which hopped from mice and bats, respectively, were plenty deadly, but did not spread person to person. Only mosquitoes (and blood transfusions, it turns out) transmit West Nile. The difference with SARS is that you can get it from someone coughing in your elevator.

Public health officials are still a bit uncertain as to just how contagious SARS is. Most cases seem to spread to close relatives or healthcare workers heavily exposed to virus-containing droplets from coughing and bodily fluids. But there have been a few breakout cases -- spread on hotel floors, airplanes and apartment buildings, for example -- that don't fit the pattern.

There appears to be a subset of "superinfectors" whose coughs produce aerosolized viral balloons that can float in the air for hours. Using the example of one Hong Kong apartment complex where more than 200 people were infected with the disease, World Health Organization officials speculated -- without offering any evidence -- that the virus occasionally spread through sewage.

The appearance of a highly contagious coronavirus would not surprise Pierre Talbot. In research conducted at a neonatal clinic in Brittany, Talbot found traces of one human coronavirus on aluminum table tops and sterile latex gloves up to three hours after patients left a room. "It survives in the environment quite easily," he says. "People are going to have to be very prudent with this virus."

Added Larry Anderson, who is running the CDC lab investigation of SARS, "This is the first new virus infection associated with such serious disease which is transmitted, we suspect, by respiratory droplets. I think it will be difficult to control the spread of SARS."

Next Page: "If it's new to the human population," she says, "it's impossible to predict"

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