Study shows rapid SARS test is 100% accurate

Toronto, ON August 25, 2003 Researchers from Toronto’s University Health Network and Mount Sinai Hospital have shown that a quick and commercially available test for SARS is 100% accurate in detecting the SARS-coronavirus in tissue samples.

The study, to be published on the Centers for Disease Control and Prevention website, is encouraging news for infection control specialists, who have struggled since the beginning of the SARS outbreak to find an available, accurate and rapid way to diagnose patients with SARS a vital first step in understanding and treating the disease, and in developing new therapies.

“This test may help take the guesswork out of identifying patients who have SARS and those who do not. With fast, accurate results we can make better decisions about when to isolate patients and how best to treat them,” says senior author of the study, Dr Kevin Kain, director of the Centre for Travel and Tropical Medicine at Toronto General Hospital of the University Health Network and professor of Medicine at the University of Toronto.

In the study, researchers identified all SARS-infected samples in a rigorous blinded trial, and did not produce any false positive results. The test, initially developed by the biotech company Artus in Hamburg, Germany, detects virus RNA using a real-time gene amplification strategy. The test can produce results within an hour unlike some tests, such as serologic assays, which can take days to weeks to become positive.

Dr Kain points out that the study also makes a crucial link between the SARS illness and the SARS-associated coronavirus (CoV). The test accurately identified samples by detecting the presence of SARS-CoV in all SARS-infected samples. The virus was not detected in non-SARS samples taken during the same time period or in samples taken from patients five years earlier. This is key evidence that SARS-CoV is a reliable indicator of who does and doesn’t have SARS.

“This research provides evidence that SARS-associated coronavirus plays a primary role in the progression of the disease,” says Dr Kain, who adds the test identified large quantities of the virus in patients even at the time of death. “It’s important for hospitals to know they can’t lower their guard. Even weeks into the illness and after death, the virus appears to be still present in large amounts, and these patients are still likely to be infectious to others.”

The fact that the virus is present in large numbers at the time of death indicates that continued viral growth is likely directly contributing to fatal outcomes. It is also important evidence that even late in disease antiviral agents may still be effective. However, ribavirin therapy used to treat most SARS patients was clearly ineffective at clearing virus in these patients, says Dr Kain. He expects that the test will help researchers develop new antiviral therapies, by allowing them to track which therapies reduce viral numbers.