Scientists said Friday they believe they have developed a test for diagnosing the mysterious flu-like illness that has sickened hundreds in Asia — a crucial step in slowing the disease's spread.
Officials with the World Health Organization said the test still needs further experimenting, but if successful, it should be in the hands of doctors in a few weeks and available in key laboratories in a few days.
"We're all very pleased. It is crucial and it's another step on the way, but there's a lot that still has to be done," said Dr. David Heymann, WHO's communicable diseases chief.
A diagnostic test would make it possible for doctors to quickly weed out and isolate patients with the new disease called severe acute respiratory syndrome, or SARS. It has made 350 people around the world ill and killed 10 people in the past three weeks, according to WHO figures.
Experts suspect it is linked to an earlier outbreak of an unidentified disease in China, where officials say 305 people have fallen ill and five have died.
It is believed to be spread from the nasal fluids of those carrying it — mostly through sneezing and coughing in close contact.
The development of the test involved isolating the germ from a sick patient and mixing it with blood from recovered patients.
"The blood from the [recovered] SARS patients kills the virus, which means the virus was previously in these people and now they have antibodies that kill the virus," said Dr. Klaus Stohr, WHO's chief influenza scientist.
"What we have now is perhaps a test," said Stohr. "If you are ill and we don't know whether you have SARS or not, we take your blood, we run this test and we know whether you have it or not. But this has to be verified — double-checked and triple-checked."
But the chief of the U.S. Centers for Disease Control and Prevention sounded skeptical.
"It's very unlikely you could have a reliable diagnostic test when you don't have an etiology," said Dr. Julie Gerberding, CDC director. She said the CDC is relying on case definitions and investigation to determine which patients have the disease.
The WHO scientist who developed the test is not yet certain what type of virus he isolated. However, the paramyxovirus family — which includes measles, mumps and canine distemper — remains the leading suspect. A new form of influenza, once the most feared scenario, is now low on WHO's suspect list, Heymann said.
Stohr said the virus is being sent to other labs in the network so that the experiments can be repeated and verified.
Once refined, the test could be used to screen healthy people to see if they are carrying the virus. It could also be used to show whether the outbreak in China was caused by the same bug that has hit elsewhere, experts said.
A network of 11 laboratories in 10 countries, coordinated by WHO, has been working around the clock to try to find the cause of the illness. While it is still not proven, the latest findings indicate a virus is at play.
Two separate labs reported Friday that genetic experiments showed that some patients were infected with a new paramyxovirus, although the research could not tell whether that virus is the one causing the illness or whether it just happened to also be in the patients' specimens.
The scientists found genes identifying the virus as belonging to the paramyxovirus family, but say it is not one of the known varieties.
However, in a puzzling twist, other labs have reported seeing something under the microscope that is suspiciously unidentifiable, but which does not resemble a paramyxovirus.
"We have here a very fast-moving network. There are many negative results that help us exclude things and there are some quite promising positive results. They have to be followed up and double-checked," Stohr said. "We are turning around in hours and days information which is normally compiled, collected and compared over months and years."