Can Rhinovirus/Enterovirus Cause Bronchiolitis in Neonates?
Yes, rhinovirus (RV) and enterovirus (EV) are established causes of bronchiolitis in neonates and infants, though they typically cause less severe acute disease compared to RSV. 1
Viral Etiology of Bronchiolitis
While RSV remains the most common cause of bronchiolitis (accounting for 60-75% of hospitalized cases), rhinovirus and enterovirus are recognized as significant etiologic agents 2:
- Rhinovirus causes approximately 21% of bronchiolitis cases requiring hospitalization in infants 3
- Enterovirus accounts for approximately 9% of cases 3
- Together, rhinovirus or enterovirus were the sole detected pathogen in 30% of bronchiolitis cases in one prospective study, making them collectively one of the leading causes 3
- The American College of Chest Physicians formally identifies rhinovirus as a primary cause of bronchiolitis alongside RSV, adenovirus, influenza, parainfluenza, human metapneumovirus, and coronavirus 1
Clinical Characteristics of RV/EV Bronchiolitis
Infants with non-RSV bronchiolitis, particularly human rhinovirus, appear to have shorter courses and may represent a different phenotype associated with repeated wheezing 2. This is an important clinical distinction:
- RV-associated bronchiolitis tends to be less severe acutely compared to RSV 4
- However, early RV infection correlates with subsequent wheezing bronchitis and asthma in later childhood and adulthood 4
- The clinical presentation remains similar across viral etiologies: rhinitis, tachypnea, wheezing, crackles, use of accessory muscles, and nasal flaring 2, 5
High-Risk Populations
Neonates with underlying conditions face increased risk of severe disease regardless of viral etiology 2:
- Prematurity (especially <29 weeks gestation)
- Hemodynamically significant congenital heart disease
- Chronic lung disease (bronchopulmonary dysplasia)
- Immunocompromising conditions
- In utero smoke exposure 2
For premature infants, one study found no apnea events in those >48 weeks postconceptional age without previous apneic events, but younger or higher-risk infants remain vulnerable 2.
Diagnostic Considerations
Routine viral testing is not recommended for clinical management of bronchiolitis 2. However, understanding the viral landscape is important:
- PCR assays can detect RV/EV, but PCR results should be interpreted cautiously as they may detect prolonged viral shedding from unrelated previous illness, particularly with rhinovirus 2
- RSV detected by PCR almost always correlates with active disease, whereas rhinovirus detection is less specific 2
- Co-infections occur in up to one-third of infants with bronchiolitis, with RV/EV frequently detected alongside other viruses 2, 3
- At the individual patient level, identifying the specific viral etiology has not been demonstrated to change management 2
Clinical Implications
The key takeaway is that diagnosis and management should be based on clinical presentation rather than viral etiology, as treatment remains supportive regardless of whether RSV, rhinovirus, or enterovirus is the causative agent 2. The exception is for infants receiving palivizumab prophylaxis who develop bronchiolitis—testing should be performed to determine if breakthrough RSV infection occurred 2.