New tests set SARS apart from cold, flu

Tests for the SARS virus will soon help doctors sort out whether people with worrisome coughs and fevers actually have the new respiratory illness, relieving anxiety for many and helping judge who should be isolated to prevent more spread.

Government agencies, university labs and private companies are all rushing to develop highly sensitive tests that will seek out the newly discovered virus and confidently allow a diagnosis of severe acute respiratory syndrome, once their accuracy has been proven.

One version created by the Centers for Disease Control and Prevention could be shipped to state labs as soon as the end of next week, officials say. Several others are being fine tuned around the world using new information compiled just last weekend from scientists’ marathon exercise of decoding the virus’s genes.

The tests, which search for viral genes in victims’ nasal secretions and other samples, are likely to work only in the early stages of the disease, before the body defeats the virus, removing all traces it existed.

They will be used cautiously at first, while developers work to prove they pinpoint the virus in infected people without sending up frequent false alarms in the healthy. Until this accuracy is known, “we will be loath to say someone doesn’t have SARS on the basis of the test,” CDC head Dr. Julie Gerberding said Thursday.

Nevertheless, experts hope the tests will soon allow doctors and public health officials to distinguish whether people with fresh symptoms have SARS or other look-alike ills, such as bad colds and flu. Then they can more knowledgeably decide whether the patients need elaborate infection control precautions in hospitals and whether their families, co-workers and friends should be watched for symptoms and perhaps even quarantined to prevent passing the virus to others.

“We could basically target our prevention at those who truly have SARS,” said Dr. Elizabeth Koch, an epidemiologist in the Ohio Department of Health.

Dr. James Hughes, head of the CDC’s National Center for Infectious Diseases, said its test would be sent to about 100 state, city and federal health labs within two weeks, perhaps as soon as the end of next week. The labs, in turn, will test samples sent to them by hospitals with suspected SARS cases.

The CDC test has already been tried on 300 randomly selected specimens, all with negative results, and on many of the 208 suspected U.S. cases from 34 states. Hughes said the result suggested the test was accurate enough for wide distribution, although it was created before scientists knew the full genetic code of the SARS virus.