Accurate Day 1 blood testing for SARS
¡@¡@The severe acute respiratory syndrome (SARS) epidemic is subsiding. Experience to date shows that the inability to confirm SARS infections objectively during the early stage of disease had been a prime hurdle to the effective control of SARS. Sensitive tests that can detect the SARS-coronavirus during the earliest stage of infection will prevent major SARS outbreaks in the future. Unfortunately, current tests fail to meet these requirements.
¡@¡@The research team led by Professor Dennis Lo, Associate Dean (Research), Faculty of Medicine, The Chinese University of Hong Kong (CUHK), in collaboration with Professor John Tam from the Department of Microbiology, has developed and evaluated a new test for SARS; its accuracy and applicability early in the course of disease represent a major breakthrough. Professor Lo has a distinguished track record in the development of novel tests based on the analysis of blood plasma. For example, he has successfully detected the genetic material of unborn foetuses from the blood plasma of pregnant women. Professor Lo's experience in blood plasma analysis has given the CUHK team a competitive advantage in developing a new blood-based test for SARS.
¡@¡@In this novel blood test for SARS, 80% of SARS patients can be positively identified on the first day of hospital admission. The test is based on the detection of the genetic material, namely RNA, of the SARS-coronavirus in blood. It accurately determines the amount of virus carried by the patient, while requiring only a small quantity of blood and a short period of analysis time. Professor Lo has focused on blood because he believes that this approach will give a more representative picture of the total virus load in the whole body.
¡@¡@The new blood test offers many advantages over existing tests, and represents a major advance in SARS testing. Existing tests based on the detection of antibodies are generally useful only 2 weeks after the start of the disease. Other tests that detect the SARS-coronavirus RNA have largely focused on the use of nasopharyngeal aspirates, urine and stools. As reported, these tests only allow the identification of 30% of the SARS patients by the third day of disease. Also, nasopharyngeal aspirates can only provide a limited picture of the virus load in specific locations of the body.
¡@¡@The performance of the new test has been confirmed by extensive evaluation. The quantitative readout of the test has provided new useful information which had not been possible to obtain previously. Testing from day 1 of hospital admission already reveals patients who have a more severe disease. All 100% of the patients who eventually need to be admitted to the Intensive Care Unit (ICU) were tested positive on day 1, and they have a median virus load that is 28 times higher than those not eventually requiring treatment in the ICU. In addition, this new test can provide a day-to-day reading of the virus load in a particular patient during the course of hospital stay. These results could potentially be used to guide treatment.
¡@¡@The development of this
new test represents a new powerful addition to our arsenal against SARS
and will provide a strong line of defense if this disease re-emerges.