2. Introduction
RSV is one of the most common viruses to infect children worldwide and increasingly is
recognized as an important pathogen in adults, especially the elderly.
RSV commonly presents in young children as bronchiolitis and can rarely progress to
pneumonia, respiratory failure, apnea, and death.
In older children and adults, reinfection with HRSV is frequent, but disease is milder
than in infancy.
The mainstay of treatment for the vast majority of RSV infections is supportive, but
passive preventive immunization is available for at-risk children.
3. RSV
RSV is a single-stranded, negative-
strand, RNA virus belonging to
the Paramyxoviridae family, and is in
the genus Pneumovirus.
The structure of RSV is that of a
bilipid-layer-envelope surrounding a
ribonucleoprotein core, with several
membrane proteins
4. Epidemiology
It infects 90% of children within the first 2 years of life and frequently reinfects
older children and adults.
Infection with HRSV is seen throughout the world in annual epidemics that
occur in late fall, winter, or spring and last up to 5 months.
Rates of illness are highest among infants 1–6 months of age, peaking at 2–3
months of age.
HRSV accounts for 20–25% of hospital admissions of young infants and
children for pneumonia and for up to 75% of cases of bronchiolitis in this age
group.
6. Risk Factors
Prematurity (gestational age of <37 weeks)
Low birth weight
Age less than 6 to 12 weeks
Chronic pulmonary disease (bronchopulmonary dysplasia, cystic fibrosis,
congential anomaly)
Hemodynamically significant congenital heart disease (pulmonary hypertension,
cyanotic heart disease, or congenital heart disease)
Immunodeficiency
Neurologic disease
Congenital or anatomical defects of airways
7. Transmission
HRSV is transmitted primarily by close contact with contaminated fingers or
fomites and by self-inoculation of the conjunctiva or anterior nares.
Virus may also be spread by coarse aerosols produced by coughing or sneezing,
but it is inefficiently spread by fine-particle aerosols.
Virus shedding may last for ≥2 weeks in children and for shorter periods in
adults.
In immunosuppressed patients, shedding can continue for weeks
8. Pathophysiology
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.
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.
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, 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.
10. History and Physical
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.
11. History and Physical
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.
Most patients recover gradually over 1–2 weeks
12. Evaluation
The diagnosis of RSV and subsequent bronchiolitis is clinical and does not require
confirmatory testing or imaging.
Antigen testing has the advantages of being quick, inexpensive, very specific, and easily
performed on nasal secretions, but has an imperfect sensitivity of approximately 80%
during RSV outbreaks.
PCR testing is becoming more common due to rapidity of results, ease of testing, higher
sensitivity rate than antigen testing, and ability to detect multiple other organisms if
performed as part of a PCR panel.
Chest x-ray findings of RSV bronchiolitis variably include hyperinflation, patchy atelectasis,
and peribronchial thickening, but may be difficult to distinguish from bacterial pneumonia.
13. Treatment
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.
14. 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
and oxygen for patients experiencing hypoxia
Patients with severe presentation and respiratory distress may require
ventilatory support in the form of a high-flow nasal cannula, CPAP, or
intubation, and mechanical ventilation.
15. Immune Prophylaxis
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.
16. Antiviral Medication
There is a single antiviral medication for use against RSV, ribavirin.
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.
Its use in RSV remains controversial due to expense and questions of
efficacy, specifically regarding mortality, length of mechanical ventilation,
and length of hospital stay.
17. Morbidity and Mortality
More likely to suffer recurrent infections.
Many have recurrent acute otitis media.
Many likely to be hospitalized with another episode of acute respiratory distress.
Adolescents suffer from allergic asthma, allergic rhino conjunctivitis, & more sensitive to
inhaled allergens.
More likely to have asthma, bronchial reactivity to methacholine, and reduced lung
function.
18. Reference
Piedimonte G, Perez MK. Respiratory syncytial virus infection and bronchiolitis. Pediatr
Rev. 2014
Hall CB, Weinberg GA, Iwane MK, Blumkin AK, Edwards KM, Staat MA, Auinger P, Griffin
MR, Poehling KA, Erdman D, Grijalva CG, Zhu Y, Szilagyi P. The burden of respiratory
syncytial virus infection in young children.
American Academy of Pediatrics Committee on Infectious Diseases; American Academy
of Pediatrics Bronchiolitis Guidelines Committee. Updated guidance for palivizumab
prophylaxis among infants and young children at increased risk of hospitalization for
respiratory syncytial virus infection. Pediatrics. 2014
