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Last Updated

19 Mar 2003

Source: New York Times, March 19, 2003

Researchers Find Clues That a Virus Is Causing the Mysterious Illness, but Seek Proof


Scientists have found clues that a virus might be the cause of the mysterious respiratory illness that has affected hundreds of people in Asia and other countries, the World Health Organization said yesterday. But the agency cautioned that much more work needs to be done to be sure that a virus is the cause of the outbreak and not merely a coincidental finding in a few patients.

Using electron microscopes, two laboratories in Germany and a third in Hong Kong reported finding particles that seem to belong to a large family of viruses, paramyxoviridae, that includes the viruses that cause croup, respiratory disease, measles, mumps and other ailments.

Still, Dr. Klaus Sthr, a virologist and epidemiologist who is leading the health organization's scientific team investigating the illness, said that none of those viruses had caused a disease like the one under investigation, which doctors are calling severe acute respiratory syndrome, or SARS. Instead, the findings suggest that the virus might be a hitherto unknown member of the paramyxoviridae family.

Tests seem to have ruled out two recently discovered members of the family, the Nipah virus and the Hendra virus, Dr. Sthr said.

Dr. James M. Hughes, the director of the center for infectious diseases at the Centers for Disease Control and Prevention in Atlanta, urged people not to draw firm conclusions from the findings. Federal health officials are not yet ready to accept the paramyxoviridiae as the final explanation, Dr. Hughes said.

The 3 laboratories are part of a network of 11 labs in 9 countries that the W.H.O. has created to find the cause of the ailment, which the agency, a unit of the United Nations, has declared "a worldwide health threat."

Yesterday, other scientists in the network raced to test throat swabs and sputum specimens from other SARS cases to see if they, too, could identify similar particles, said Dr. Sthr, the W.H.O. virologist.

One of the patients in whom the viral particles were found is a doctor from Singapore who recently flew to New York City for a medical conference. On his way home, he was taken off a plane in Frankfurt and hospitalized there, along with his traveling companions his wife and his mother-in-law. All three are showing symptoms, though it is not clear that the two women have SARS.

The doctor's condition is improving, but his wife who is 13 weeks pregnant, is in isolation, Dr. Hans-Reinhard Brodt, the director of the isolation ward, said at a news conference at the German hospital.

The doctor and his mother-in-law are being treated with four antibiotics, and his wife is receiving a different set of antibiotics to avoid possible damage to her fetus.

They are sharing the same quarters in the hospital, watching television and reading newspapers. Rene Wendell, the head nurse, said they were "having second thoughts about whether they should have made the trip" from Singapore to New York.

The W.H.O. said that since Feb. 1, it had received reports of 219 cases, including four deaths, from nine countries Canada, China (including Hong Kong), Britain, Germany, Singapore, Slovenia, Taiwan, Thailand and Vietnam.

Chinese officials have reported an additional 305 cases, including 5 deaths, from November to Feb. 1 in Guangdong province.

No cases have been reported from the United States. But epidemiologists from the Centers for Disease Control and Prevention are investigating nine possible cases.

Although the toll had risen to 219 from 169 on Monday, W.H.O. officials were encouraged to learn that the condition of 13 of 57 patients in Vietnam had improved sufficiently to remove them from the critical list. Some received antibiotics and some antiviral drugs, said Dr. David L. Heymann, executive director in charge of communicable diseases for the W.H.O.

But W.H.O. officials were concerned about the possibility that a new case of SARS in Vietnam has no known link to other cases.

"We still don't have a specific treatment" for SARS, Dr. Heymann said.

Dr. Heymann added that the information was based on individual cases and not on a scientific analysis of larger numbers of patients.

One reason for the W.H.O.'s caution, Dr. Heymann said, is that "it would be a shame if doctors changed treatment regimens to accommodate this tentative finding and then it turns out to be something else."

Another reason for caution is that members of the paramyxoviridae family commonly cause infection during the influenza season, and thus the presence of such viruses would not be surprising, experts said.

Dr. Hans-Wilheim Drr, the director of the Institute of Medical Virology in Frankfurt, said the finding of a paramyxoviridae virus "could just be a coincidence, because this is the flu season."

"It is one of several possibilities, but this is the most obvious possibility," said Dr. Drr. His institute and the Institute for Virology in Marburg identified the viral particles.

Dr. Heymann said that if the viral particles are a meaningful clue, "a definitive diagnosis will come fast if it is a known member of the family."

Even if a paramyxoviridae virus is found to be the cause of illness in the three patients in Germany and Hong Kong, it still could be unrelated to the cause of the larger outbreak.

Despite the caveats, there was a sense of cautious optimism among the scientists who had been frustrated by the inability to find any clues to what might be causing SARS.

"No question, it's an infectious disease," said Dr. Anthony S. Fauci, the director of the National Institute of Allergy and Infectious Diseases in Bethesda, Md. "But what is the microbe?"

With the finding of suspect paramyxoviridae particles, Dr. Heymann said, "we're happy because we finally have one lead to follow" as the possible cause of the disease.

But he emphasized the findings are only "a hint and still premature" because the electron microscope is not a way to make a definitive diagnosis.

Yet, as Dr. Fauci said, "it is a tool to steer you in the right direction."