ISOLATION, AN OLD MEDICAL TOOL, HAS SARS FADING
21 Jun 2003
Source: New York Times, June 19, 2003
Isolation, an Old Medical Tool, Has SARS Fading
By KEITH BRADSHER with LAWRENCE K. ALTMAN
HONG KONG, June 20 — Three months ago, SARS appeared poised to sweep the world, a mysterious new disease racing out of southern China for which there was no vaccine, cure or diagnostic test.
Today, SARS is disappearing almost as fast, and almost as unpredictably, as it arrived. This week, the World Health Organization declared it under control, with only a handful of cases worldwide in the last week.
The agency's only remaining advisory against travel — to Beijing — is expected to be lifted in a few days. Hong Kong, the city with more cases and deaths relative to its population than anywhere else, has had no new cases since June 2.
The epidemic could come back, doctors say, perhaps with the return of colder weather. But for now, health officials and infectious disease experts are racing to learn what they can from the sudden rise and retreat of SARS, or severe acute respiratory syndrome: what caused it to spread; what strategies worked to contain it; and what might work the next time a new disease jumps from animals, as SARS seems to have done, and begins spreading rapidly among people.
Reassuringly, SARS appears to have been controlled mainly through one of the oldest of medical tools: isolation. This has been done through better infection controls in hospitals, as well as by the early quarantining of the close personal contacts of infected individuals, so that if they later fell sick, they would not spread the disease to even more people.
The approach succeeded because SARS appears to be transmitted mainly by fairly large droplets that travel no more than five feet through the air, instead of staying airborne and potentially floating through several floors of a building, as smallpox can. And while some patients have proved highly infectious, others have not, for reasons that remain unclear.
"These are medieval health measures that have worked," said Dr. Mike Ryan, a senior World Health Organization expert on communicable diseases. "If it had been truly airborne, the measures we have chosen would not have been effective."
The containment effort succeeded in part because of the extraordinary collaboration among scientists summoned by the agency, and in part because some countries, including the United States, had geared up their public health systems in anticipation of a bioterrorist attack.
Health officials say SARS has taught them several other lessons: the need to develop a reliable test to detect it in its early stages and distinguish it from other flulike or pneumonialike diseases; the potential volatility of the virus that causes it; and the growing importance of international travel in spreading communicable diseases.
Many public officials and businesspeople in affected countries, appalled by the damage the W.H.O.'s travel advisories did to trade and tourism, have suggested that fears about SARS were overblown. And it is true that the worldwide death toll has been modest: 801, or about one-sixth the number that tuberculosis kills in a single day.
But doctors with firsthand experience of the disease say the risk was real. If the disease had not been controlled, they contend, it could have spread globally and with devastating results, given an overall death rate estimated at 15 percent (and more than 50 percent for people 65 and older).
The W.H.O. has found that a single patient can spread the disease to as many as 100 other people in some settings, especially hospitals, although it is more common for each infected person to infect two or three others if no precautions are taken.
"I think there was a possibility of being a global pandemic if the appropriate control measures were not taken," said Dr. Thomas Tsang, the epidemiologist who oversaw investigations into the worst outbreaks in Hong Kong. "If we didn't put in the control measures, this disease would have spread through the world like other respiratory diseases."
That possibility has not been entirely extinguished by the decline of the SARS epidemic, experts say. They worry that the disease is really still present, slowly being transmitted among people who do not become very sick, and will burst loose again next autumn and winter, perhaps with even greater virulence.
Researchers believe that SARS is caused by a virus from the corona family, which also causes a third of all common colds. Colds tend to be seasonal, raising the worry that SARS will prove seasonal as well.
"There's obviously a seasonality with this thing; otherwise we wouldn't see it disappearing like this quite so effectively," said Dr. Robert Webster, a virologist at St. Jude Children's Research Hospital in Memphis. "It's not just the quarantine that's been so effective. Nature has been giving a helping hand."
Other experts question whether seasonality played a big role in the control of the virus. Dr. Alfred Sommer, the dean of the Johns Hopkins Bloomberg School of Public Health in Baltimore, points out that Singapore brought its outbreak under control despite having minimal fluctuations in temperature because it is practically on the Equator.
"Now that is not to say," he added, "that we're not in for a really bad surprise come the fall and the following winter."
Hong Kong and nearby Guangdong Province in mainland China are each studying the construction of special infectious-disease hospitals or hospital wings to get them through this winter. "I know they're gearing up for this as is every other country," said David L. Heymann, the W.H.O.'s executive director for communicable diseases.
The United States is planning for the possible return of SARS the way it would for a pandemic of influenza. The focus will include "detecting cases, responding to W.H.O.'s call for technical assistance or field team assistance in various parts of the world, and having reliable diagnostic tests available where they are needed," said Dr. Julie L. Gerberding, the director of the Centers for Disease Control and Prevention in Atlanta.
"It would be foolish to not have that kind of plan available for us," Dr. Gerberding said.
Simply identifying SARS next winter may prove difficult because it is easily confused with influenza and other respiratory illnesses. That is why health officials say developing a reliable diagnostic test for SARS is a top priority. "When winter comes, there are going to be many, many background diseases which fit the case definition," Dr. Heymann said, adding that they will have to be treated carefully just in case they are SARS. "It's a massive undertaking," he said.
As the disease fades, hospitals even in some of the areas hardest hit this spring are starting to return to normal while doctors and nurses begin going back to previous duties. At the Prince of Wales Hospital in Hong Kong, where a sick 26-year-old infected 112 health workers in early March, the number of SARS patients has plunged from 160 to just 9.
"We are still worrying about the ongoing possibility of recurring epidemics," said Dr. Justin Wu, a gastroenterologist who spent two months treating SARS patients at Prince of Wales Hospital. He has returned to research because the number of patients has dwindled.
Several worries remain. One is that China's aggressive effort to halt the disease now, which includes punishments for local officials who let it spread, could discourage accurate reporting of cases. During the 1950's and 1960's, Chinese cities and villages publicly humiliated people who contracted sexually transmitted diseases by denouncing them in front of co-workers and accusing them of being burdens on society. Infected people stopped reporting cases, and these ailments practically vanished from some Chinese medical textbooks in the 1970's on the theory they had been vanquished, only to be revealed again as a big problem in the last few years.
Another concern is that researchers in Hong Kong and Guangdong say they have found viruses nearly identical to the SARS virus in several species of wild animals sold for meat in local marketplaces. Nobody knows whether those animals long harbored the disease or happened to catch it in a market stall from some other animal. Nor does anybody know whether the disease passed once from animals to humans in a fluke incident or was transmitted in a manner easily repeated. All of these factors will affect the likelihood of recurrent outbreaks.
Another lesson of the SARS epidemic, widely noted when it was first spreading out of control in Hong Kong, is the need for prompt and accurate reporting.
China's disastrous experience — covering up the first cases of SARS and then watching the disease spread worldwide — "made clear to the public, as seldom has happened, that honest, accurate information is necessary for rational health policy," said Dr. Barry R. Bloom, the dean of the Harvard School of Public Health.
"In infectious diseases, it helps no one to either deny you have a problem or to be dishonest in reporting it," he continued, "because if you do, and you do have spread, you are going to get caught."
Typical of the efforts against SARS has been the work at the Guangdong Respiratory Diseases Control and Prevention Research Institute, which occupies a weathered hospital facing the murky waters of the Pearl River in Guangzhou, China, 80 miles upstream of Hong Kong. Dated on the outside but surprisingly modern within, the hospital holds what officials insist are the Chinese province's last three SARS patients, all in serious condition and in isolation on the sixth floor.
Guangdong now has so few infections, after 688 cases in February alone that began spreading the disease to Hong Kong and elsewhere, because of what Dr. Wang Zhiqiong, the provincial deputy director of health, describes as the "four earlies" policy: early detection, early reporting, early isolation and early treatment. These policies, among the oldest tenets of epidemiology, have been echoed in response to every other SARS outbreak.
The speed with which SARS spread through Hong Kong and on to other places underlined another lesson that doctors say they have learned from SARS: the city's medical importance and its vulnerability to disease.
Hong Kong sits on the edge of southern China, an incubator of many epidemics because of its very dense population living in close proximity to many animal species, and the source of some of the global outbreaks of influenza and bubonic plague as well as SARS. Britain's transfer of Hong Kong to China in 1997 and subsequent efforts to ease border controls are now allowing residents of southern China to come here in extraordinary numbers, with as many as four million border crossings a month by people who may be carrying all types of germs.
The cramped layout of Hong Kong makes diseases harder to control once they reach the city's forests of 40-story skyscrapers packed with family apartments of 200 to 500 square feet. Hong Kong's role as Asia's busiest air transportation hub, at least until SARS hit, can then allow the 70 airlines operating here to carry the latest Chinese microbes to every continent.
"Hong Kong is at the crossroads of the world, certainly," said Dr. Heymann of the W.H.O. "It's not only susceptible to many diseases coming in, but also to exporting diseases, and they travel around the world."
His colleague Dr. Ryan said the early appearance and rapid spread of SARS in Hong Kong had initially seemed like the fulfillment of one of his oldest nightmares.
"My personal fear in life was always this kind of epidemic in a highly populated area," he said. "This epidemic had the potential to spread globally and cause far more outbreaks than it did."
But Hong Kong has managed to control the disease, though only after 1,755 cases and 295 deaths. Its containment program began to succeed when officials started going to unusual lengths to track down the personal contacts of SARS patients. Hong Kong sent police detectives to hunt down the family members and close friends of SARS patients and confine them in their homes.
Such tactics stirred concerns about infringement of civil liberties, not just in Hong Kong but also in other cities, including Toronto and Singapore. But in general, the approach here won plaudits from public health officials.
"I'm convinced that the way that the health authorities, the Department of Health and the police department have begun to work together on this outbreak will be not only copied in future outbreaks here in Hong Kong but in cases throughout the world, because it's a very important marriage of databases," Dr. Heymann of the W.H.O. said at a news conference here.
In Toronto, the number of SARS cases is ebbing, but health officials have been cautious about declaring the outbreak over, having made the assertion in mid-May only to find the disease was spreading unchecked through two Toronto hospitals.
Health officials were dealt a further blow on Wednesday when scientists at the country's national microbiology lab in Winnipeg, Manitoba, said they had found that 120 people from the Toronto area tested positive for the SARS coronavirus but were never considered SARS patients, raising the possibility that the stubborn virus still lingers in the city.
Such concerns tinge the present mood of optimism with wariness at the possibility of renewed outbreaks. Even in the United States — which so far has escaped the brunt of SARS, with just 409 cases and no deaths — there is no room for complacency, said Dr. William Schaffner of Vanderbilt University in Nashville.
"SARS showed the country once again," he added, "how really thin the front lines are in health departments."