Respiratory Syncytial Virus in Infants & Children

Respiratory syncytial virus (RSV) causes acute respiratory tract illness in individuals of all ages. The clinical manifestations vary with age, health status, and whether the infection is primary or secondary. The focus of this article will be on infants and children.

Incubation Period: 4-6 days 

Cold or Rainy Seasons: RSV causes seasonal outbreaks, usually appearing as wintertime epidemics in colder climates. In tropical climates, the seasonal outbreaks are usually associated with the rainy season. 

Young Children: RSV is the most common cause of lower respiratory tract infection in children <1 years of age. Almost all children are infected by 2 years of age and reinfection is common. The hospitalization rate is greatest amongst infants that are <3 months of age, however, a large number of the hospitalizations happen in children >6 months. 

Older Children: RSV hospitalization may also occur in children greater than 5 years of age, however, they usually have underlying medical problems, such as Trisomy 21, immunodeficiency. 

Risk Factors for Lower Respiratory Tract Infection: 

• Infants <6 months of age - their risk is increased if they are attending daycare and if they have older siblings. 
• Infants and children with underlying lung disease, such as chronic lung disease
• Infants and children with congenital heart disease
• Infants exposed to secondhand smoke 
• Children with Down Syndrome are at increased risk for severe RSV illness 
• Immunocompromised children 
• Children and infants with significant asthma 

• Lower respiratory tract disease - Infants and young children with primary infections usually present with lower respiratory tract infections, such as bronchilitis, pneumonia, and acute respiratory failure 
• Apnea - RSV can cause significant apnea in infants, which may often be the presenting symptoms in infants admitted to the hospital with RSV 
• Wheeze - 1/5 of infants <1 year develop RSV-associated wheezing, with 2-3% requiring hospitalization 
• Upper respiratory tract signs & symptoms - RSV infection may cause cough, rhinorrhea, coryza, conjunctivitis, and sinus and ear involvement 

Clinical Diagnosis

Typically, RSV is suspected in children with the clinical features and risk factors. This includes age <1 year, lower respiratory tract disease, winter season, and known circulation of RSV. For children and infants that are previously healthy presenting with typical bronchilitis, clinical suspicion of RSV is usually sufficient. 

Laboratory Investigations

Analysis of respiratory secretions collected via nasal wash, nasopharyngeal swab, or throat swab can also be performed. 

Treatment for RSV infection of the lower respiratory tract infection is primarily supportive.

• Inhaled bronchodilators - not routinely recommended for infants and young children with bronchioloitis but a one-time trial can be used for those demonstrating severe respiratory distress. 
• Hospitalization for monitoring and fluids
• Respiratory support - hospitalization for respiratory support (O2) for those infants with SpO2 <90%; if severe respiratory symptoms, apnea, or respiratory fatigue due to RSV, mechanical ventilation may be required