Editorial Commentary: Respiratory Syncytial Virus: A Global Pathogen in an Aging World

Abstract

Respiratory syncytial virus (RSV) was identified in 1957 as a cause of infant bronchiolitis and is now recognized as the major cause of hospitalizations for respiratory infection in young children [1]. Shortly after its discovery, mild illness in adults with RSV reinfection was observed and since the 1980s evidence has been slowly mounting that the burden of adult RSV disease is substantial [2, 3]. Groups at highest risk for severe infection include the elderly, persons with chronic cardiopulmonary diseases, and those with immunosuppression [4, 5]. Despite the currently available epidemiologic data, RSV infection is rarely considered by internists evaluating patients with respiratory illness in their offices or in the hospital. In addition, health agencies and industry remain uncertain as to whether adult RSV disease warrants programs to develop therapeutics and vaccines. The reason for the adult RSV “identity crisis” is in large part because physicians rarely make a specific viral diagnosis in an individual patient and thus, they are unable to personalize the disease. Insensitive pointof-care diagnostics, the lack of a distinct clinical syndrome, and a broad epidemic curve that overlaps with influenza and other respiratory viruses all contribute to this lack of recognition of the problem. The development of new sensitive molecular diagnostics have dramatically altered epidemiologic research involving respiratory viruses, and recent studies now provide a more accurate picture of the burden of RSV disease [6, 7]. Yet, here too, the global community cannot personalize the problem to their own region or countries as most studies to date are from Europe and North America. Unless a disease is demonstrated in one’s own backyard, there is a natural tendency to ignore or minimize the problem. In this issue of Clinical Infectious Diseases, Lee and colleagues [8] present data from a large, 3-year study of adults hospitalized with respiratory illness in Hong Kong, China. In this study, the clinical and radiologic features of 607 adults with confirmed RSV infection are compared and contrasted to patients with seasonal influenza infection. The findings clearly demonstrate significant morbidity and mortality in older persons associated with RSV infection, which is comparable to influenza. RSV accounted for 6%–9% of respiratory illnesses during seasonal peaks; 72% of those admitted with RSV had lower respiratory tract complications, 11% required ventilatory support, and 9% died within 30 days. Similar to previous reports, infected patients were elderly (mean age, 75 years), and most had underlying medical conditions with chronic lung disease reported in 36%. Of note, although substantial proportions of both RSV and influenza patients had underlyin g medical conditions, RSV patients had significantly more lung disease and major systemic comorbidities. This observation may reflect the very large sample size of the current study allowing detection of more subtle differences in patient groups than previous reports. Importantly, there was no significant difference in the overall outcomes of survival and duration of hospitalization of RSV- and influenza-infected patients. Although a number of the observations