Skip to main content

SARS 10 years on: How dogged detective work defeated an epidemic

By Peter Shadbolt, CNN
updated 5:26 AM EST, Thu February 21, 2013
STORY HIGHLIGHTS
  • Hong Kong housing estate Amoy Gardens was center of 2003 SARS outbreak
  • Authorities had to work fast to isolate the virus and quarantine residents
  • The events at Amoy Gardens underscored the difficulties of containing epidemics
  • Public information an important part of the fight against epidemics

Hong Kong (CNN) -- In scenes that would not have been out of place in a Hollywood science fiction thriller, at dawn on March 31, 2003, armed police and Hong Kong health authorities dressed in biological suits, theater masks and surgical gloves descended on Amoy Gardens housing estate.

Working swiftly on an order from the Department of Health to isolate Block E, the residents were sealed in. Under 24-hour medical surveillance, they could neither leave the block nor receive visitors, according to a report from the Hong Kong Department of Health.

Later moved to confinement camps under quarantine laws that had not been invoked since an outbreak of bubonic plague in 1894, the residents of Amoy Gardens were locked out for 10 days as doctors, clinicians, sewerage experts and engineers scoured the block for clues.

READ: How SARS brought city to its knees

But even before Block E could be quarantined, police were on a manhunt for 147 residents who had already fled the infected apartment block -- to hotels or to stay with family or friends -- possibly spreading the virus into the community.

If SARS (Severe Acute Respiratory Syndrome) -- then a new and barely understood type of pneumonia -- demonstrated anything, it was that rumor and panic spread almost as fast as the virus.

SARS was a wake up call... what it showed us is that the world of infectious diseases is ever present
Gabriel Leung, Hong Kong University

"Good, proactive communication that provides accurate information in a timely fashion is certainly one of the lessons of SARS and to some extent this was implemented during the (swine flu) pandemic of 2009," said Professor Malik Peiris of the Centre of Influenza Research at Hong Kong University.

READ: Global epidemics -- Lessons learned

"But there were even lessons to learn from 2009 because communicating like this in a crisis is difficult and challenging precisely because you are in a situation of grossly imperfect knowledge," he said.

In the case of Amoy Gardens, epidemiologists and health authorities were faced with a serious dilemma -- find out how the deadly virus was spreading, but contain panic that could send more infected people into the wider community.

Almost immediately, worried residents filled the information vacuum themselves, launching the website sosick.org.

SARS: the toll

- WHO says there were 8,096 cases of SARS worldwide
- It registered 774 deaths around the world
- The disease had a 9.5% fatality rate globally
- SARS spread from mainland China to Hong Kong and then to 37 countries
- The death toll was more than 50% for those over 65
- Hong Kong recorded 299 deaths, with 1755 contracting the disease
- Hong Kong's fatality rate was 17%, the highest in the world

Collecting information from residents on infected buildings, the website was able to record the spread of SARS from Amoy Gardens to nearby Lower Ngau Tau Kok Estate a week ahead of the authorities, according to reports at the time.

But if government information on the Amoy Estate outbreak was perceived to be lacking, the investigation (conducted at speed) to establish how the disease was spreading was a masterpiece of medical detective work.

While people in Hong Kong had been coming down with the virus at the rate of 50 a day, the infection could be traced to contact with a person showing symptoms of the disease.

Now, at E-block Amoy Gardens, more than 200 people had contracted the virus almost overnight and their only connection was that they lived vertically above or below each other in the same apartment block.

Ultimately, a total of 329 residents at Amoy Gardens came down with SARS and 42 were to die, 22 of them at Block E, .

Within 24 hours a team of experts found evidence the building's sewerage was involved in the vertical spread of the virus.

Intense diarrhea from one of the patients -- a 33-year-old Shenzhen resident in Hong Kong for kidney treatment and identified only as patient YY -- was believed to have spread the disease through defective piping in the building.

SARS was a 21st century disease in its mode and speed of spread. But it was eventually defeated using 19th century tools
Margaret Chan, WHO

According to the Department of Health, a break in E block's flush-water system earlier that month had meant the water-sealed S-bend in some of the apartments' toilets had been dry for an extended period, allowing virus-laden droplets to collect from the system's soil pipe.

Bucket flushing by residents may have disturbed and released contaminated droplets, government agencies said. Similarly, exhaust fans may have sucked droplets into bathrooms where the virus was deposited on floor mats, towels, toiletries and toothbrushes.

Even then, the government had to work quickly to quash panic sparked by medical conjecture that exhaust fans had drawn contaminated droplets into the building's light well, a disturbing development, if it had been true, that would have meant the virus was airborne.

For Hong Kong's government, Amoy Gardens was a turning point.

"The general public expects things to be cut and dried with clear answers -- obviously that may not be possible all the time. The lesson is that one really needs to be upfront in communicating uncertainty," Peiris said.

Margaret Chan, Director General of the World Health Organization, but then head of the Hong Kong Department of Health, said the fight against SARS was a triumph of dogged medical work.

"SARS taught the importance of meeting an emergency with whatever tools are at hand," she told the South China Morning Post. "SARS was a 21st century disease in its mode and speed of spread. But it was eventually defeated using the 19th century tools of case detection, contact tracing, isolation and infection control."

In terms of epidemiology, the study of the spread of diseases, the lessons from SARS were that the categories of epidemic diseases and their modes of transmission may never end.

SARS was believed to have originated in civet cats at the exotic food markets of southern China, leaping the species barrier through human contact, possibly even through the food chain.

According to Professor Gabriel Leung, the head of the Department of Community Medicine at Hong Kong University, the spread of disease does not just work in one direction. Virologists, he said, are now looking at how viruses pass, not just from animals to humans, but from humans to animals and then back to humans again.

"SARS was a wake up call, not just to Hong Kong but to the rest of the world and what it showed us is that the world of infectious diseases is ever present. Microbes will always be with us and we can never proclaim -- as we did in the 60s and 70s -- that the book on infectious diseases is closed," Leung said.

"It reminds us that human health and veterinary health are one and the same thing and we need to be constantly vigilant," he added. "We are linked to animals not just by contact but also by the food chain and the latest horse meat scandal is a good illustration of that."

ADVERTISEMENT
Part of complete coverage on
updated 8:39 PM EDT, Mon September 22, 2014
He's one of the fieriest political activists in Hong Kong — he's been called an "extremist" by China's state-run media — and he's not old enough to drive.
updated 5:29 AM EDT, Tue September 16, 2014
Christians in eastern China keep watch in Wenzhou, where authorities have demolished churches and removed crosses.
updated 1:38 AM EDT, Wed September 10, 2014
Home-grown hip-hop appeals to a younger generation but its popularity has not translated into record deals and profits for budding rap artists.
updated 1:45 AM EDT, Tue September 9, 2014
Reforms to the grueling gaokao - the competitive college entrance examination - don't make the grade, says educator Jiang Xueqin.
updated 8:18 AM EDT, Fri September 5, 2014
Beijing grapples with reports from Iraq that a Chinese national fighting for ISIS has been captured.
updated 10:00 PM EDT, Sun August 31, 2014
CNN's David McKenzie has tasted everything from worms to grasshoppers while on the road; China's cockroaches are his latest culinary adventure.
updated 8:57 PM EDT, Thu September 4, 2014
Beijing rules only candidates approved by a nominating committee can run for Hong Kong's chief executive.
updated 3:14 PM EDT, Fri August 29, 2014
China warns the United States to end its military surveillance flights near Chinese territory.
updated 11:12 PM EDT, Thu August 28, 2014
China has produced elite national athletes but some argue the emphasis on winning discourages children. CNN's Kristie Lu Stout reports
updated 1:13 AM EDT, Tue August 19, 2014
Chinese are turning to overseas personal shoppers to get their hands on luxury goods at lower prices.
updated 5:08 AM EDT, Fri August 15, 2014
Experts say rapidly rising numbers of Christians are making it harder for authorities to control the religion's spread.
updated 12:52 AM EDT, Mon August 11, 2014
"I'm proud of their moral standing," says Harvey Humphrey. His parents are accused of corporate crimes in China.
updated 3:42 PM EDT, Wed August 6, 2014
A TV confession detailing a life of illegal gambling and paid-for sex has capped the dramatic fall of one of China's most high-profile social media celebrities.
updated 12:10 AM EDT, Thu July 31, 2014
President Xi Jinping's campaign to punish corrupt Chinese officials has snared its biggest target -- where can the campaign go from here?
updated 3:12 AM EDT, Wed July 30, 2014
All you need to know about the tainted meat produce that affects fast food restaurants across China, Hong Kong, and Japan.
updated 10:30 PM EDT, Thu July 17, 2014
Some savvy individuals in China are claiming naming rights to valuable foreign brands. Here's how companies can combat them.
updated 5:11 AM EDT, Wed July 16, 2014
Is the Chinese president a true reformist or merely a "dictator" in disguise? CNN's Beijing bureau chief Jaime FlorCruz dissects the leader's policies
updated 11:44 PM EDT, Mon July 7, 2014
With a population of 1.3 billion, you'd think that there would be 11 people in China who are good enough to put up a fight on the football pitch.
ADVERTISEMENT