Severe Respiratory Viral Infections: New Evidence and Changing Paradigms.

Lower respiratory tract infection is a leading cause of death in the United States. Advances in diagnostic testing have improved our ability to detect pathogens. Viral pathogens are important causal pathogens in immunocompetent patients. As the number of elderly adults and those with chronic medical conditions increases, the burden of viral respiratory infections will increase. Clinicians must be familiar with the characteristics of rhinovirus, human adenoviruses, respiratory syncytial virus, and human metapneumovirus. Major challenges include distinguishing true infection from asymptomatic carriage and characterizing patients admitted with severe lower respiratory tract infection who do not have a causative pathogen identified.