sars病原與檢測(cè)ppt課件-資料下載頁(yè)
2025-01-05 03:30本頁(yè)面
【正文】 (inhibition control) ?If a positive PCR result has been obtained, it should be confirmed by: ?repeating the PCR using the original sample ?OR ?having the same sample tested in a second laboratory. ?Amplifying a second genome region could further increase test specificity Use of laboratory methods for SARS diagnosis WHO Remendations on interpretation of laboratory results ?Remendations for laboratories testing for SARS ?Remendations for laboratories testing for SARS Reference laboratories should be identified at national level. ? PCR testing Laboratories testing for SARS by PCR should already have experience with PCR testing. They should adopt quality control procedures and identify a partner laboratory in their country or among the WHO collaborating research laboratories listed in Multicentre Collaborative Network: Laboratories testing for SARS to crosscheck their positive findings. ?Laboratories performing SARS specific PCR tests should adopt strict criteria for confirmation of positive results , especially in low prevalence areas, where the positive predictive value might be lower. ?A PCRkit for SARS is mercially available, including internal controls. PCR primers and procedures have been published and can be adapted by laboratories. Positive control RNA is available from the BernhardNocht Institute in Hamburg, Germany. ?The sensitivity of PCR tests for SARS depends on the specimen and the time of testing during the course of the illness. This may result in real cases of SARS testing negative by PCR (false negative results). Sensitivity can be increased if multiple specimens/ multiple body sites are tested. ?The specificity of PCR tests for SARS is excellent if technical procedures used follow quality control guidelines. False positive results may arise as a result of technical problems (. laboratory contamination), so every positive PCR test should be verified. ?Antibody testing ELISA and IFA tests are being developed by research laboratories. ?Because SARS a new disease in humans, SARSCoV antibodies are not found in populations that have not been exposed to the virus. ?An antibody rise between acute and convalescent phase sera tested in parallel is very specific.
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