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Viruses cause most pediatric infections. Mixed viral or viral-bacterial infections of the respiratory and intestinal tracts are common, as is prolonged asymptomatic shedding of many viruses in childhood, especially in young children. Thus, the detection of a virus may be indicative of infection, but it may not always be the cause of a presenting illness or disease. Viruses are often a predisposing factor for bacterial respiratory infections (eg, otitis, sinusitis, and pneumonia). See Table 40–1 for an outline of viral illnesses described in this chapter.
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The epidemiology of respiratory viruses is frequently changing, as is demonstrated by the recent emergence of SARS-CoV-2, and the impact that social distancing measures had not only on COVID-19 disease but many other respiratory viruses as well. As the world adapts to the post-pandemic phase of COVID-19 pandemic, previous and current patterns of seasonality, transmission, diagnosis, and even treatment and prevention may change significantly.
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Many respiratory viruses and herpesviruses can now be detected within 24 hours through antigen or nucleic acid detection techniques. Polymerase chain reaction (PCR) amplification and sequencing of viral genes is leading to detection of previously unrecognized infections. It is now possible to detect multiple organisms causing the same syndrome (eg, respiratory, gastrointestinal, encephalitis/meningitis) within a single test system (multiplex assay). The available tests vary in format and turnaround time and can include both viral and bacterial etiologies. New diagnostic tests are challenging our previous paradigms of viral infections and their diagnosis more certain and complex brining along new therapeutic opportunities. Therefore, as a clinician and provider, it is critical to consult the microbiology laboratory for details regarding the optimal specimen collection, handling and shipping, and only laboratories with excellent quality-control procedures should be used. Table 40–2 lists diagnostic tests. The increasing availability of specific antiviral therapies increase the value of early diagnosis for some serious viral infections. Table 40–3 lists common causes of ...