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Chapter 68 : Rapid Viral Diagnosis
This chapter presents an overview of rapid viral diagnosis, focusing on the advantages and limitations of common methods used, the factors involved in test selection, the validation and monitoring of test performance, and the critical importance of sample collection. The methods used for rapid viral diagnosis can be generally grouped according to the following strategies: (i) direct detection of viral proteins, nucleic acid, or particles in clinical specimens; (ii) biologic amplification of infectious virus in cell culture followed by detection of viral antigens in cultured cells; and (iii) detection of an immunoglobulin M (IgM) antibody response to viral infection. Advantages and limitations of these methods are listed in this chapter. With the exception of electron microscopy (EM), rapid tests detect only the specific agent(s) sought. In general, the most rapid approach is to detect virus directly in clinical samples, rather than wait either for virus to grow in culture or for an antibody response to occur. Lastly, it has been shown that when physicians call the laboratory for advice prior to sample collection, the isolation rate doubles. The choices for rapid viral diagnosis continue to increase. The number and types of techniques chosen will vary with the individual viruses, laboratory expertise, and clinical needs and will continue to change as both test methods and antiviral therapy evolve and improve.