Scientists at the Chinese University of Hong Kong said the test, which detects genetic material of the SARS virus in blood plasma, can help doctors screen severely affected patients as soon as they are hospitalized.

That gives them better notice as to which ones will need intensive care.

The new screening takes about five hours and can also identify SARS patients who do not have fevers, said Dr Dennis Lo, a chemical pathologist who headed the study.

A lack of typical SARS symptoms -- high fever, headaches and dry cough -- among some patients has been identified as a key factor in the disease's spread.

"This major breakthrough will drastically reduce cross-infections in hospitals and prevent large-scale outbreaks in the future," Lo told a news conference.

Dr Hitoshi Oshitani, a World Health Organization regional adviser on communicable disease, surveillance and response, said the new test method could be very useful, but larger-scale studies were needed to see how well it works.

"We do need a better diagnostic test for SARS, that's clear. But all these findings need to be verified," Oshitani said from his office in Manila, the Philippines.

Lo said that checks on blood samples from 30 patients using the test identified all those who were eventually admitted into intensive care units. The amount of virus such patients carried was on average 28 times higher than that carried by patients with milder forms of SARS, he said.

"If we are able to find out on the first day of hospitalization which patients have the more severe form of the disease, we can try new treatment methods to save them," Lo said.

Previous diagnostic tests that checked for the virus in either nose and throat secretions or in urine and stool samples had about a 30 percent accuracy rate for detecting the disease, Lo said.

(Eastday.com June 24, 2003)