Editorial Commentary: Plethora of Respiratory Viruses and Respiratory Virus Data

In this issue of Clinical Infectious Diseases, Byington et al report on findings from the BIG-LoVE (Better Identification of Germs Longitudinal Viral Epidemiology) study [1]. Based on serial molecular testing for respiratory viruses carried out on a defined population, BIG-LoVE provides a wealth of information about the relationship between respiratory symptoms and respiratory viral infection. The study stands squarely in the tradition of the historic community-based studies of viral respiratory infection, including the Cleveland Family study [2], the Tecumseh study [3], and the New York and Seattle Virus Watches [4, 5]. Those studies, which were based on viral culture and/or serology, established our current conceptual framework for the community epidemiology of viral respiratory tract infection. BIG-LoVE is one of a new generation of communitybased studies [6] that “flesh out” that framework by using molecular methods that are more sensitive than previous methods. BIG-LoVE resembles the classic studies by being community based, with specimens obtained from study participants on a regular basis, regardless of the presence or absence of symptoms, but the study stands out by virtue of the intensity of virologic and clinical surveillance undertaken. A total of 108 individuals in 26 households from the University of Utah campus community provided symptom diaries and self-collected anterior nasal swab samples weekly for 52 consecutive weeks. Diaries also included information on absence from work or school and on medical visits. To the credit of the investigative team, diaries and specimens were available for analysis from 77% of episodes. Each week was characterized with regard to occurrence of illness based on the symptom diary and presence or absence of respiratory viruses as measured by the molecular test. Illness episodes were defined as continuous periods of presence of symptoms, and virus episodes were defined as continuous periods of detection of the same virus. While the study has the significant strengths described above, it also has limitations. The numbers of households and participants were relatively small. In addition, the study was confined to a single community during a single year. With participants being recruited from a university community, the study population was probably more educated and from a higher socioeconomic stratum than the general US population. The molecular test was a developmental version of the FilmArray Respiratory Panel multiplex respiratory panel [7], and the performance characteristics of this test version were not provided. Each of these factors suggests caution in generalizing the results of the findings. Furthermore, molecular detection of viral nucleic acid is not conclusive proof of active infection. With these caveats in mind, the study nevertheless provides highly useful information. Molecular detection is rapidly becoming the major method used for detection of respiratory viruses in clinical settings, and BIG-LoVE provides data that will help clinicians interpret the results of current molecular assays. Like previous studies [6, 8], BIG-LoVE documents the impressive frequency of respiratory symptoms and infection with respiratory viruses that are present in the community at any given time. Respiratory symptoms were present in 38% of personweeks for children aged <5 years and 20% of person-weeks for older children and adults. Participants experienced a mean of 5 respiratory illness episodes per year, with more in children aged <5 years. Sixty percent of respiratory illness episodes were associated with detection of 1 or more viruses. Interestingly, virus-positive Received 6 June 2015; accepted 9 June 2015; electronically published 4 August 2015. Correspondence: Gregory Storch, MD, Washington University School of Medicine, 660 S Euclid Ave, Campus Box 8116, St. Louis, MO 63110 (storch@wustl.edu). Clinical Infectious Diseases 2015;61(8):1225–7 © The Author 2015. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals. permissions@oup.com. DOI: 10.1093/cid/civ487