The pathology department at the University of Hong Kong is one of the few places on Earth where you can stare death in the face. In the department's lab, a transmission electron microscope capable of magnifying an image up to 150,000 times is being used to view a never-before-seen virus that researchers now believe has killed at least 55 people worldwide and infected more than 1,500. Illuminated on a green phosphorescent screen by a beam of electrons and viewed through an optical device that resembles an upside-down periscope, the virus—this particular specimen had been taken from a relative of a Chinese doctor who was the first victim to die in Hong Kong on March 4—looks every bit the alien matter that it is. "There are the little buggers," says Dr. John Nicholls, a pathologist at the University of Hong Kong, leaning aside so a TIME reporter could take a look. Magnified 100,000 times, the organisms are fuzzy black balls that fill the screen and look like the burrs that stick to your pants during a hike through the woods. You can just make out the little hooks sticking out of the viral body—telltale characteristics that help classify the pathogens as members of the coronavirus family.
Coronaviruses, so called because of their spiky crown of protein globules, are generally not mortally harmful. They are a pest to livestock and in humans are responsible for more than one-third of common cold cases. But the bugs on Nicholls' slide have, for reasons researchers have just begun to investigate, mutated into something far deadlier: a rogue virus that triggers a killer pneumonia recently labeled Severe Acute Respiratory Syndrome (SARS). Since news of the first SARS cases escaped mainland China a month ago, health authorities around the planet have been in a state of high alert, fearful of a worldwide outbreak of a highly contagious and untreatable disease. Last week the disease continued to go global, affecting more than 15 countries, as infected individuals jetted from hot zones to other parts of the world, passing along their unwelcome baggage through sneezes and coughs. Most worrisome, the disease doesn't look like it will die out anytime soon: Thomas Tsang, consultant in community medicine at Hong Kong's Department of Health, says he expects to see as many as 50 new cases a day over the next few weeks—just in the territory alone.
SARS, which is believed to be a form of atypical pneumonia, has already claimed some high-profile victims, including a World Health Organization (WHO) doctor who came into contact with patients in Hanoi and succumbed on Saturday. Secretive Chinese health-care authorities—the disease is suspected to have first surfaced last November in the southern Chinese province of Guangdong—now admit that the country has far more cases and in more places than previously acknowledged. Last week they put the toll at 806 cases and 34 deaths, a statistic that many mainland doctors say still underplays the disease's real effect. In Canada's Ontario province, where 35 people have been stricken and of whom three have died, access to medical facilities has been severely restricted and officials ordered thousands of people to self-quarantine. In Singapore and Hong Kong, schools were ordered closed and governments invoked quarantine laws not used for decades to isolate those who might be carriers. Nearly 1,700 Singaporeans are now confined to their homes. Explained Hong Kong's Chief Executive Tung Chee-hwa in announcing tougher measures to curb the spread of the disease: "Hong Kong is currently facing its most serious contagious disease threat in 50 years."
Drastic steps are being taken in part because so little is known about SARS. Scientists have only begun to deconstruct the virus' DNA to find out where it originates from, how it kills and, crucially, how to counteract it. According to the WHO, the coronavirus, while it can spread quickly, is actually less contagious than the average influenza virus. But once inside a human host, it can be virulent. The pathogen causes high fever and creates an "inflammatory storm" as the body's immune system attempts to fight it off, says one doctor, causing lung tissue to swell and, in the final, brutal stages, suffocating the host. Nguyen Thi Bich, 44, a nurse at Hanoi's French Hospital, where nearly 60 SARS cases have been traced, contracted the disease and was hospitalized for three weeks. "The fever felt like having red ants in my body," she says. "Sometimes I felt my body was about to explode." She was lucky and recovered. But Bich's friend and colleague, nurse Nguyen Thi Uyen, died of SARS. Although the virus appears to attack indiscriminately, once contracted its effects are generally more harmful in the elderly or those with pre-existing medical conditions. "On a scale of 1 to 10, [the disease] is a 12," says Dr. Sydney Chung, dean of the medical faculty at the Chinese University of Hong Kong. "The outcome is that a significant proportion get very ill and end up on a ventilator."
Hong Kong has the unfortunate distinction of being the epicenter of the SARS outbreak outside of mainland China. The first known case to die outside the mainland was in the territory, and nearly 500 people have contracted the virus since then. Just last week, 310 new cases came to light. Still, that's just a fraction of Hong Kong's 7.3 million population, and in fact, the SARS mortality rate isn't very high—fewer than 4% of those who have contracted the disease so far have died. But the limited death toll belies the much wider impact SARS is having on the city's economy and psyche. Indeed, in Hong Kong there seem to be two contagions at work: one is the virus, which is transmitted when a person comes into contact with pathogen-laden droplets; the other is fear, which has spread swiftly through the community, stoked by sentiment that the territory's beleaguered government hasn't done enough to stem the disease's spread.