Viral Testing and Isolation of Patients With Bronchiolitis

In this issue of Pediatrics, Harris et al1 raise important issues that highlight the importance of controlling the spread of infections among young ill children.The goal of the clinical practice guideline “Diagnosis and Management of Bronchiolitis”2 was to provide recommendations for the diagnosis and management of children between 1 month and 2 years of age with bronchiolitis, based on the best available evidence, for pediatricians, family physicians, emergency medicine specialists, hospitalists, and others who care for these children. The guideline, therefore, is addressed primarily to this large and varied group of mostly primary care providers. Certainly, situations occur that require alternate emphasis and adjustments of the recommendations. Some of these we noted, but in most instances it is the individual clinician who is best able to determine the exception. The guidelines are not intended to replace clinical judgment.Children with unrecognized underlying conditions would be among these exceptions. We specifically noted in the guidelines that the recommendations do not apply to children with high-risk underlying conditions, including those with congenital immunodeficiencies, those with HIV, or those who have had an organ or bone marrow transplant. Although bronchiolitis may be the first illness for such children, in most cases these underlying conditions are already known. Viral testing of all children with bronchiolitis would not be cost-effective and, in most instances, would not lead to the diagnosis of the underlying condition. The diagnosis would more likely be suspected by the atypical course of the initial episode of bronchiolitis, which would direct the clinician toward additional paths of investigation.Other reasons for viral testing exist, such as for research and epidemiologic monitoring, as noted by Harris et al.1 Such monitoring is mainly performed by institutions that are involved in bronchiolitis or other viral research and by those who participate in their region's public health epidemiologic surveillance. These and other activities aimed at detecting emerging infection and assessing the efficacy of prophylaxis and treatment are specialized situations in which few primary physicians participate. Thus, they are not within the purview of our guideline.Preventing the spread of respiratory syncytial virus (RSV) and other infectious agents is of utmost importance and was addressed in our guidelines2 (recommendations 9a, 9b, and 9c and the following text). Viral testing could and should enhance such preventive programs. It is important, however, to clarify what is meant by “viral testing.” For hospitalized or outpatient children with bronchiolitis, essentially the only viral diagnostic tests available for immediate management are the rapid screening tests for RSV and, to some extent, those for influenza. The reliability of these screening tests is highly variable depending on the prevalence of the virus in the community, how long the child has been ill, and the adequacy of the specimen obtained. More sensitive isolation and molecular techniques are costly and rarely available. Furthermore, in the case of reverse transcriptase–polymerase chain reaction, its sensitivity allows prolonged detection of such small amounts of virus that the clinical importance is unclear (ie, not correlated with contagion). These are important considerations in many situations in which viral identification could be helpful, such as those noted by Harris et al.1In the guidelines we acknowledge the potential value of viral testing in cohorting patients. In most instances, however, this involves screening for RSV and does not indicate the presence of the high rates of coinfection that occur during the bronchiolitis season in these young children.3–6 Therefore, the primary mode of prevention of transmission must be the use of infection-control procedures. Except for hand sanitation, the efficacy of specific additional precautions, such as use of gowns, gloves, and masks, are not entirely clear.7–9More important is understanding the risks and modes of transmission of the agents that are most likely to infect infants during the bronchiolitis season, which, to our current knowledge, are primarily RSV, influenza, the parainfluenza viruses, rhinoviruses, adenoviruses, and human metapneumovirus. Although these agents may spread by more than 1 mode,9,10 most of them, including influenza, seem to be primarily spread among children by close contact with an infected individual through large-particle aerosols that traverse distances of <3 feet or by direct contact with fomites that are contaminated by infectious secretions.7,9–13 Infection control, therefore, may depend less on identifying a specific virus (especially considering the limited testing available) than assuring compliance with appropriate precautions such as the cleansing of hands and fomites, separating infants in multiple-bed rooms by at least 3 feet, and other recommended measures.Because of the complexities and importance of the spread and control of infectious agents among children, we could not address these important issues in detail in our guidelines. The Healthcare and Infection Control Practices Advisory Committee, the Centers for Disease Control and Prevention, and other recognized expert bodies must continue to set evidence-based standards of practice in this area.