Tests confirm cause of SARS

By Rob Stein
Washington Post

The alarming new lung infection that has triggered an international health emergency is unquestionably caused by a previously unknown virus related to germs that cause the common cold, the World Health Organization announced yesterday.

A Philippine Airlines employee, left, took the temperature of a Manila-bound passenger at Hong Kong's international airport to check for symptoms of severe acute respiratory syndrome. Associated Press

While researchers have been focusing on the virus as the probable cause of SARS for several weeks, the definitive connection is nonetheless a crucial milestone in the global health crisis. It will allow scientists around the world racing to fight the epidemic to focus exclusively on the virus, speeding development of better tests, aiding efforts to find a treatment and accelerating work to produce a vaccine.

"We now know with certainty what causes SARS," David Heymann, executive director of the WHO's communicable disease program, said in Geneva. "Now we can move away from methods like isolation and quarantines and move aggressively toward modern intervention strategies, including specific treatments and eventually vaccination."

Heymann said that while the primary route of SARS transmission is through droplets that infected people spray out when they sneeze or cough, scientists had also detected evidence of the virus in feces and urine.

This would explain why many victims experience diarrhea and other gastrointestinal symptoms, and it could mean the virus can be transmitted through waste. That would provide one explanation for how the disease spread rapidly through a Hong Kong apartment tower, an outbreak that has puzzled and alarmed researchers, he said.

Efforts to contain the disease have focused primarily on identifying and isolating sick people before they spread the virus. That appears to have been effective in some places, such as Hanoi, Singapore and Toronto. But the disease is still spreading in Hong Kong and mainland China, and sporadic new possible cases continue to be reported throughout the world.

While several tests have been developed for the virus, none is precise enough to answer key questions, such as whether people can spread the virus before and after their symptoms begin and end.

The microbe's genes don't appear similar to any other known coronavirus, suggesting it has been hiding in nature in southern China, perhaps in an animal, said Masato Tashira of the National Institute of Infectious Diseases in Tokyo. There were only two previously known human coronaviruses — so-called because of their distinctive crown-like shell — and they cause about one-third of all colds. Other coronaviruses infect many animals, sometimes causing severe respiratory or gastrointestinal diseases.

The announcement firmly associating the coronavirus to SARS was made at a meeting of scientists from 13 laboratories in 10 countries that the WHO called to review the state of knowledge about the disease one month after the agency declared an international emergency because of it. The scientists represent an unprecedented global network the WHO quickly assembled last month to fight SARS.

The conclusion came after researchers in the Netherlands produced two final pieces of evidence: Monkeys infected with the virus developed a disease identical to that seen in humans, and scientists were able to then find the virus in the animals.

"We can with all confidence say the causative agent of SARS is the coronavirus," said Albert Osterhaus of the Erasmus Medical Center in Roterdam, who led the research.

At least 3,293 suspected cases have been reported in 23 countries, and 159 victims have died. Hong Kong and China have been hit hardest. Outside Asia, Toronto is the worst SARS hot spot. U.S. health officials are investigating at least 199 cases in 34 states.