Worldwide, it is estimated that RSV is responsible for approximately 33 million lower respiratory tract illnesses, three million hospitalizations, and up to , childhood deaths; the majority of deaths are in resource-limited countries. There is seasonal variation in RSV incidence, but seasonal effects vary with worldwide geography; temperate climates have a marked winter-spring predominance, and tropical and equatorial climates may have less pronounced spikes with the more interseasonal disease.
Morbidity and mortality are significantly higher in a subset of patients, including premature infants, patients with preexisting cardiac, pulmonary, neurologic, and immunosuppressive disorders, and the elderly. RSV is spread from person to person via respiratory droplet, and the incubation period after inoculation with RSV ranges from 2 to 8 days, with a mean incubation of 4 to 6 days, depending on host factors such as the age of the patient and whether it is the patient's primary infection with RSV.
After inoculation into the nasopharyngeal or conjunctival mucosa, the virus rapidly spreads into the respiratory tract, where it targets its preferred growth medium: apical ciliated epithelial cells. There it binds to cellular receptors using the RSV-G glycoprotein, then uses the RSV-F fusion glycoprotein to fuse with host cell membranes and insert its nucleocapsid into the host cell to begin its intracellular replication. Host inflammatory immune response is triggered, including both humoral and cytotoxic T-cell activation, and a combination of viral cytotoxicity and the host's cytotoxic response cause necrosis of respiratory epithelial cells, leading to downstream consequences of small airway obstruction and plugging by mucus, cellular debris, and DNA.
More severe cases may also include alveolar obstruction. Other downstream effects include ciliary dysfunction with impaired mucus clearance, airway edema, and decreased lung compliance. Histopathology does not play a significant role in the diagnosis of RSV and the findings in mild disease are not known, but histopathologic findings of severe disease include abundant respiratory epithelial cell death, airway edema, and immune cell infiltration, initially polymorphonuclear early in the illness, and later in the illness, lymphomononuclear.
RSV typically manifests as an upper respiratory illness, with the possibility of lower respiratory tract involvement, and historical and examination findings differ based on the location and severity of the disease. If limited to the upper respiratory tract, RSV presents with rhinorrhea, nasal congestion, cough, sneezing, and sometimes fever and myalgia. In some patients, especially those with risk factors for severe disease who are under the age of 2 years, RSV will progress to lower respiratory tract involvement with various permutations of the classic findings of bronchiolitis: rhonchorous breath sounds, tachypnea, accessory muscle use, wheezes, and prolonged expiration.
In severe cases, it may also present with findings of viral pneumonia, hypoxia, lethargy, apnea, and acute respiratory failure. The diagnosis of RSV and subsequent bronchiolitis is clinical and does not require confirmatory testing or imaging. Testing for RSV is discouraged unless the fact of its presence would alter medical decision-making.
Specific testing for RSV may be useful to differentiate from other disorders and is available in two commonly used forms: rapid antigen testing and polymerase-chain-reaction-based PCR testing.
Antigen testing is quick, inexpensive, specific, and is easily performed on nasal secretions. PCR testing is increasingly more common due to the proliferation of the technology, rapid results, ease of testing, a higher sensitivity rate than antigen testing, and the ability to detect numerous other organisms when performed as part of a PCR panel.
The disadvantages of PCR testing include the cost of the test and the need for specialized equipment to process the test. Radiographic findings in RSV are identical to bronchiolitis in general, and are non-specific, and require interpretation in the context of the patient's illness.
Chest x-ray findings of RSV bronchiolitis may include hyperinflation, patchy atelectasis, and peribronchial thickening; however, these may be difficult to distinguish from bacterial pneumonia. Treatment for RSV falls into three categories: supportive care, immune prophylaxis, and antiviral medication.
The majority of RSV and bronchiolitis cases require no specific medical intervention, and many attempted treatments throughout history are ineffective. The mainstay of treatment for patients with RSV is supportive care. The spectrum of supportive care includes nasal suction and lubrication to provide relief from nasal congestion, antipyretics for fever, assisted hydration in the event of dehydration assistance may be by mouth, by nasogastric tube, or intravenously , and oxygen for patients experiencing hypoxia.
Hospitalization is recommended for patients who are experiencing or are at risk for moderate to severe disease, patients requiring supplemental fluids, and patients requiring respiratory support. Effective passive immune prophylaxis for RSV exists in the form of palivizumab, a humanized murine monoclonal antibody with activity against the RSV membrane fusion protein required for fusion with host cell membranes. Palivizumab must be administered monthly for the duration of the RSV season.
Palivizumab is relatively expensive and is the subject of some debate regarding cost-effectiveness. The American Academy of Pediatrics publishes guidelines regarding which patients are candidates for palivizumab and its discontinuation in breakthrough infection, and we refer readers to those guidelines for specific recommendations regarding palivizumab eligibility. Broadly, these recommendations include prophylaxis for children in the first year of life with: prematurity less than or equal to 29 weeks gestational age, chronic lung disease of prematurity, congenital heart disease, or neuromuscular disorders.
It is a nucleoside analog with application in several RNA viruses, and it shows in vitro activity against RSV and may be administered in aerosolized form. However, its use in RSV remains controversial due to expense, questions of danger to exposed health care providers, and questions of efficacy, specifically regarding mortality, length of mechanical ventilation, and length of hospital stay.
Ribavirin's routine use is discouraged, but it may be considered on a case-by-case basis. Many other treatment modalities for bronchiolitis have been tried in the past, and all others have failed to show broad, reproducible efficacy on clinically significant outcomes in RSV and bronchiolitis. These include albuterol, racemic epinephrine, steroids, hypertonic saline, antibiotics, and chest physical therapy, and routine use of these interventions is not recommended. Children hospitalized secondary to RSV infection usually recover without sequelae.
They are discharged in 3 to 4 days. High-risk infants have longer hospitalizations and have higher rates of mechanical ventilation and admission to the intensive care unit.
People infected with RSV are contagious for 3 to 8 days. However, some infants, and people with weakened immune systems, can continue to spread the virus even after they stop showing symptoms for as long as 4 weeks.
There is evidence that severe RSV infection and hospitalization for RSV early in life raise the risk for the development of recurrent wheezing, childhood asthma, and allergic sensitization. Moreover, there is some evidence that palivizumab prophylaxis may decrease the incidence of later recurrent wheezing in treated subjects. However, the extent, duration, and mechanism of a link between RSV and asthma has not been fully elucidated and remains a subject of vigorous research.
RSV is a very common childhood infection and often leads to many visits to the emergency room, which in the end also increase the cost of healthcare. No history of intubation. No or mild retractions. Information from references 12 and RSV bronchiolitis has a more severe clinical course than non-RSV bronchiolitis, including a longer hospital stay. However, chest radiography should not be performed routinely because it does not improve clinical outcomes and is associated with increased antibiotic use.
The mainstay of therapy for acute RSV bronchiolitis in infants and children is supportive care Table 2. Pulse oximetry alone is an unreliable measure of hypoxemia and respiratory distress, and continuous use is optional in infants and children with bronchiolitis. Its use is implicated in increased hospitalization rates without significant change in mortality.
Maintaining the nutrition and hydration status of infants with bronchiolitis is an important factor in management. Infants with respiratory rates greater than 60 breaths per minute may have poor feeding secondary to difficulty breathing or copious nasal secretions.
Bronchodilators should not be administered to infants and children with bronchiolitis. Despite short-term improvement in clinical symptom scores, they have no effect on the need for hospitalization, oxygen saturation, length of hospitalization, or disease resolution. This analysis also included studies of children with recurrent wheezing, such as those with asthma, who are known to respond to bronchodilators.
Epinephrine should not be administered to children with bronchiolitis in the inpatient setting. A Cochrane review of first-time wheezing among infants showed a statistically significant reduction in admission rates in patients who received nebulized epinephrine compared with placebo. However, this reduction was found on only the initial day of presentation, and there was no statistically significant reduction in the overall admission rate, likely because of the relatively short-acting effects of epinephrine.
Systemic or inhaled corticosteroids should not be used to treat bronchiolitis in any setting. Antibiotics should not be administered to infants and children with bronchiolitis and should be reserved for those with concomitant bacterial infection. Other treatments with no clear clinical benefit include chest physiotherapy and excessive nasal suction of secretions.
Although nasal suctioning provides relief of symptoms, excessive or deep nasal suctioning is associated with longer hospitalization. On the other hand, failure to perform routine external suctioning every four hours is also associated with increased length of stay.
RSV is highly contagious and is transmitted through direct contact with respiratory droplets. Secretions can remain infectious for more than six hours on hard surfaces such as tabletops, cribs, and toys. Alcohol-based hand solutions are recommended for health care professionals; soap and water should be used if these are not available. Infants at risk of severe lower respiratory tract infection should receive immunoprophylaxis with palivizumab Synagis.
Five doses provide six months of coverage, which is sufficient protection for the RSV season. The initial recommendations for palivizumab in and again in were based on the results of two randomized, double-blind, placebo-controlled trials that reported a reduction in RSV hospitalization among high-risk infants who received palivizumab. Palivizumab Synagis is not recommended for otherwise healthy infants born at or after 29 weeks, 0 days' gestation.
Palivizumab is recommended in the first year of life for infants born before 29 weeks, 0 days' gestation. Palivizumab is recommended in the first year of life for infants with hemodynamically significant heart disease. Palivizumab is recommended in the second year of life for children with chronic lung disease who require continued medical intervention e. Consider prophylaxis for infants younger than one year who have pulmonary abnormalities or neuromuscular disease that impairs the ability to clear upper airway secretions, or for children younger than two years who are profoundly immunocompromised.
Information from reference This article updates previous articles on this topic by Dawson-Caswell and Muncie , 46 and by Steiner.
The searches included meta-analyses, randomized controlled trials, clinical trials, and reviews. In addition, references in these resources were searched. Search dates: June , April , and November The views expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the Department of the Navy, the Department of Defense, or the U.
The authors are military service members. This work was prepared as part of their official duties. Title 17 U. Already a member or subscriber? Log in. Interested in AAFP membership? Learn more. Family Medicine Residency Program. Address correspondence to Dustin K. Reprints are not available from the authors. Meissner HC. Viral bronchiolitis in children. N Engl J Med.
Respiratory syncytial virus. Philadelphia, Pa. Severe human lower respiratory tract illness caused by respiratory syncytial virus and influenza virus is characterized by the absence of pulmonary cytotoxic lymphocyte responses. J Infect Dis. Clinical practice guideline: the diagnosis, management, and prevention of bronchiolitis [published correction appears in Pediatrics. Diagnosis and management of bronchiolitis. AAFP clinical practice guideline. Updated December Accessed May The burden of respiratory syncytial virus infection in young children.
Respiratory syncytial virus-associated hospitalizations among children less than 24 months of age. RSV is transmitted through contact with respiratory droplets either directly from an infected person or self-inoculation by contaminated secretions on surfaces. Patients with RSV bronchiolitis usually present with two to four days of upper respiratory tract symptoms such as fever, rhinorrhea, and congestion, followed by lower respiratory tract symptoms such as increasing cough, wheezing, and increased respiratory effort.
In , the American Academy of Pediatrics updated its clinical practice guideline for diagnosis and management of RSV bronchiolitis to minimize unnecessary diagnostic testing and interventions. Bronchiolitis remains a clinical diagnosis, and diagnostic testing is not routinely recommended.
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