MASKS OFF - FOR NOW
29 Jun 2003
Source: Newsday, June 29, 2003
Masks Off - for Now
By Laurie Garrett, Staff Writer
The Asian world is breathing a sigh of relief.
SARS, the disease that appeared with no warning seven months ago, posed a threat far beyond infection. The health of countries, not just people, was at stake. National economies, tourism, foreign investment -- all were pummeled by the appearance of the virulent, previously unknown disease labeled severe acute respiratory syndrome.
Today Asia is getting back to business. The World Health Organization last week removed Beijing from its SARS-related travel advisories, leaving only Taiwan and Toronto on the list of potential danger sites. Hong Kong plans to throw a multimillion-dollar party headlined by an all-star roster including the Rolling Stones, Ricky Martin and former President Bill Clinton, hoping to lure long-gone tourists.
But scientists and public health experts say the nations of Asia had better brace themselves; it simply isn't possible to eradicate a disease that remains a mystery. For all that has been learned in the four months since SARS' emergence was made public, many questions still don't have answers.
And even as the toll has leveled off -- the number of cases worldwide stands at 8,450 and deaths at more than 800 -- and the masks have come off, public health officials have begun to confront the spectre that SARS may not be finished -- and that it could return as early as the fall.
At last week's World Health Organization SARS meeting in Kuala Lumpur, Malaysia, doctors and scientists rattled off a list of concerns, among them:
Where did the virus come from? Does it have a seasonal cycle? Why was Vietnam able to stop its outbreak in about two weeks, but Toronto is at three months and counting?
Moreover, if SARS does come back, have the nations of the world learned about the importance of openly reporting its presence? Can China, which kept the early outbreak hidden, be expected to behave any differently?
"The world challenge now will be to keep the resources and interest in pursuing this disease," Dr. David Heymann, who heads epidemic responses for WHO, said in an interview.
Finding the Source
Today, though the leading theory is that the SARS virus jumped from animals to humans, the identity of the animal -- or animals -- has not been confirmed. And that's information researchers say is vital if a second wave is to be fought successfully.
In late May researchers from the University of Hong Kong, led by Dr. Yuen Kwoh-yung, announced they had isolated the SARS virus from the blood, urine and feces samples of an animal known as a masked palm civet. It is sold as food in an exotic live animal market in Shenzhen just across the border from Hong Kong. The virus was subsequently found in other species, including raccoon dogs and Chinese badgers. Guangdong health authorities said tests in several such markets found that 66 percent of the animal sellers and handlers tested positive for SARS antibodies.
These findings seemed to jibe with earlier discoveries that chefs who worked in restaurants that featured such exotic animal meats were among those sickened in the outbreak's early wave. Other studies began to find that the virus could grow in the suspect animals, and half of the civet farmers Yuen tested carried antibodies against the virus.
It looked like an open and shut case: SARS came from civets or badgers or raccoon dogs slaughtered by restaurant chefs and eaten by Cantonese diners. But the certainty was short-lived.
One thousand civet ranchers in Taiwan filed a $10 million lawsuit Tuesday, relying on a study by Beijing Agricultural University claiming to have found no SARS evidence in 720 animals collected in Guangdong markets. The ranchers -- charging that the researchers hurt their business -- said SARS had been found in many species, including reptiles, and that the announced findings represented nothing more than laboratory contamination.
SARS scientist Wolfgang Preiser of the University of Frankfurt, who carried out some of WHO's earliest investigations in China, said it's too early to pinpoint where SARS came from but believes the Hong Kong researchers are closing in on the culprit.
"The reason for such conflicting data obvious: On one hand, people are breaking hot news to the media; on the other, the interests of the food industries and officials are to keep everything quiet," Preiser said. "Nevertheless, [the questions] are very urgent; for one of the potential sources for a re-emergence of SARS are clearly animals."
Preiser pointed out that about half of all SARS cases in Guangdong were never connected to human contact, and many could have come directly from animal contact. If that is the case, he says, SARS eventually will come back, via the same animals.
The array of species could represent contagion within the markets, WHO virologist Dr. Klaus Stohr said in a telephone interview from Beijing. A visit to Chau Tau Market in Guangzhou in May found animals housed in tiny wire cages stacked five or six high. Almost all animals had wounds, and they urinated, bled and defecated on one another. The market was watered down periodically with a high-powered fire hose, blasting the feces into aerosolized bits.
The molecular biology indicates the virus is probably new to all the animals in these markets, as well -- except, of course, whichever species is SARS' natural host. And one intriguing finding, Stohr said, is that scientists have found animals that, despite making strong antibody responses against the virus, are passing SARS in their stools and urine. This is biologically contradictory, he insists.
"So we are all in the dark," he said.
A Seasonal Disease
If SARS is likely to re-emerge, when should Asia expect to see it again?
Despite new restrictions on the sale and trade of such animals, consumer demand -- particularly among the Cantonese -- remains high. Dining on ostriches, bullfrogs and cobras is more than a culinary tradition; it is key to ancient notions of health and long life. A recent poll found that half of all Chinese -- not just the Cantonese -- admit to eating exotic animals on occasion.
Guangdong authorities say restaurant worker Huang Xingchu, who worked in kitchens that slaughtered exotic animals, was the first SARS case, in November. But details of Huang's illness are vague, including the date his symptoms began, because he disappeared, fleeing the stigma associated with SARS.
Is it likely SARS will return in the late fall? Experts say the answer at this point is maybe.
Officials in Guangdong point out that Cantonese people consume animals in seasonal patterns -- mammals primarily when there is fear of the "cold diseases" of winter, such as tuberculosis and pneumonia. So if SARS is present in civets or other mammals, human contact with the virus would commence about November as animals are butchered and consumed.
Yet another line of reasoning argues that seasonal habitat patterns may make animals more vulnerable to hunters during the fall or lead to seasonal infections in animals.
"I don't think we are in a position yet to answer any of these questions," Preiser insisted.
Most human cases remain unexplained. The basics of human-to-human transmission are known: The virus is carried in human droplets from the lung, nose or mouth into the air, where they are inhaled directly by another person. Or transmission may be indirect, when a person touches a surface on which droplets fell, then touches his or her mouth, nose or eyes. A Hong Kong study showed that none of the doctors and nurses who consistently used face masks and washed their hands while treating SARS patients contracted it.
But there are suspicions that some guests in Hong Kong's Metropole Hotel in February -- when an ailing professor from China was a guest -- contracted SARS by touching an elevator button. All who got sick had stayed on the ninth floor, and would have been pressing the same elevator button.
The March outbreak of more than 320 cases in Hong Kong's Amoy Gardens condominium complex presented another possible transmission route. Most residents were young people who, despite their youth, got very sick, suffering not only respiratory symptoms but also gastrointestinal illness. Researchers discovered the virus was being passed in the patients' stools and urine.
A probe determined the first Amoy Gardens case was a 33-year-old man from Shenzhen, China, who visited in March when he was ill, suffering from diarrhea. Authorities concluded the virus spread through his feces, and possibly when his contaminated hands touched banisters, doorknobs and elevator buttons.
Yet investigators still need to determine how much of a role the plumbing system played: How much fecal material was aerosolized into people's apartments through faulty plumbing systems? And how much from contamination of doorknobs and other surfaces?
Controlling the Spread
There is the possibility SARS could re-emerge without any animal involvement. Many patients have recovered and continue to pass live viruses in their stools and urine, raising the possibility of transmission through plumbing or doorknobs and banisters.
"If there is environmental transmission, then this disease can come back," Heymann warned.
Researchers have established that the SARS virus can survive on plastic or hard surfaces for hours. And the colder the environment, the longer the virus lives. Bound to human fecal material, it can survive for up to five days, scientists reporting to WHO said.
Puzzles also remain about transmission within hospitals. Topping the list: Why was impoverished, resource-scarce Vietnam able to control its outbreak in about two weeks, while sophisticated, high-tech Toronto, Hong Kong and Singapore struggled for months?
The Vietnam outbreak started in Hanoi's French Hospital Feb. 28, before Guangdong's epidemic was known to the outside world and before the virus was identified. Italian Dr. Carlo Urbani, who worked for WHO, specializing in infectious diseases, set up systems of infection control and subsequently died of SARS.
About a week after the first case surfaced, Urbani shut down French Hospital, moving SARS patients into the nearby public Bach Mai Hospital. He also insisted to Vietnamese government leaders that they notify world health authorities.
"By dealing with the outbreak openly and decisively, Vietnam risked damage to its image and economy," Brigg Reilly of Médecins Sans FrontiPres (Doctors Without Borders), who worked at Urbani's side, wrote last month in the New England Journal of Medicine. "If it had decided to take refuge in secrecy, however, the results might have been catastrophic."