Diagnosis of Viral Infections

Accurate diagnosis of viral infections enhances the ability of the clinician to make decisions on appropriate treatment of patients, evaluate disease progression and prevent misuse of antibiotics. Knowledge of the pathogen involved also allow implementation of infection control and monitoring of success of antiviral treatments that may affect the prognosis of patients. Epidemiological data collected through accurate diagnostics play an important role in public health through identification and control of outbreaks, implementation of appropriate diagnostic tests, vaccination programs and treatment but also to recognize common and emerging pathogens in a community. It is key that the clinician have an understanding of appropriate specimens to send to the laboratory and the value of specific nucleic acid and serological testing for different viral pathogens. Molecular techniques have revolutionized viral diagnoses over the past decade and enhanced both the sensitivity and specificity of tests and the speed by which a diagnosis can be made and new tests be developed. The continued use of serology for viruses with a short viremia, or for chronic infections should however complement these tests. This chapter aims to provide an overview of the available tests, the principles of testing and appropriate tests to select for different viruses and syndromes. Also provided is a glimpse of new developments in diagnostics that may further enhance the capacity to make a conclusive diagnosis in the near future.