Respiratory Syncytial Virus

Respiratory syncytial virus (RSV) is one of the most common agents of lower respiratory illnesses (including bronchiolitis and pneumonia) in infants and young children worldwide.

Epidemiology

Prevalence – epidemics occur in late fall and winter and account for 5-15% of community-acquired pneumonias
Age
- 50% of children ≤1year are infected
- 100% are infected by 3 years
- Immunity wanes with age; disease may reoccur in patients >65 years
Transmission – via respiratory droplet

Organism

RSV, an enveloped RNA virus, is a member of the Paramyxoviridae family
- Two subtypes – A, B

Risk Factors for Severe Disease

Premature birth (<35 weeks gestation)
Compromised immune system
Advanced age (>65 years)
Chronic lung/heart disease (eg, bronchopulmonary dysplasia, cyanotic congenital heart disease)
Low socioeconomic status

Clinical Presentation

Symptoms
- Children
  - Infection varies from nasal congestion and upper respiratory tract infection to bronchiolitis, pneumonia, severe respiratory distress and respiratory failure
    - Grunting, nasal flaring, and retractions reflect severe disease
  - RSV can be fatal – often believed to be the cause of sudden death in infants with respiratory disease
- Adults
  - Infection generally mild – may cause severe pneumonitis in immunocompromised patients and the elderly
  - In older children and adults, RSV can also cause influenza-like syndromes, bronchopneumonia or exacerbation of chronic bronchitis

Treatment

Supportive
Antivirals frequently used in immunocompromised patients and children <2 years

Prevention

RSV prophylaxis with immunoglobulin for children <2 years and for at-risk populations (preterm infants, immunosuppressed patients and those with congenital heart disease)

Indications for Testing

Differentiate moderate lower respiratory tract infection from other viral illnesses during RSV season and allow initiation of ribavirin

Laboratory Testing

Testing not routinely recommended by the American Academy of Pediatrics
- Does not change management of disease
- If testing appears necessary and patient is not at obvious risk for RSV, consider panel testing for influenza, parainfluenza, RSV, and adenovirus
Point-of-care testing (POCT) is available (Binax NOW^® RSV) – accuracy comparable to POCT for influenza
DFA testing – rapid testing; frequently performed as a panel
- Requires nasopharyngeal swab or aspirate
PCR testing
- Requires nasopharyngeal swab or aspirate
- Less rapid than DFA
- More expensive
Antibody testing – may need both acute and convalescent serum testing
- More sensitive than viral culture in adults
- Not usually helpful in acute setting

Differential Diagnosis

Tests generally appear in the order most useful for common clinical situations

Test name: Respiratory Syncytial Virus DFA

ARUP #: 0060288

Methodology: Direct Fluorescent Antibody Stain

Use:

Rapid test that identifies RSV as the infectious agent of a pneumonia

Test name: Respiratory Syncytial Virus Antibodies, IgG & IgM

ARUP #: 0051087

Methodology: Semi-Quantitative Enzyme-Linked Immunosorbent Assay

Use:

Confirm negative DFA result; acute and convalescent samples are necessary for accurate diagnosis

Follow-up:

Repeat testing in 10-14 days may be helpful if test results are equivocal

Test name: Respiratory Viruses DFA with Reflex to Respiratory Virus Mini Panel by RT-PCR

ARUP #: 2002565

Methodology: Direct Fluorescent Antibody Stain

Use:

DFA identifies the infectious agent of a pneumonia

Panel includes influenza A and B, parainfluenza (1,2,3), RSV, adenovirus, human metapneumovirus (hMPV)

If DFA is negative or inadequate for influenza, Respiratory Virus Mini Panel by RT-PCR will be added

Limitations:

Adequacy of the direct specimen significantly influences the sensitivity of DFA

Inadequate specimen collection or too few cells on the slide may lead to failure of direct smears

Test name: Respiratory Viruses DFA with Reflex to Viral Culture

ARUP #: 0060281

Methodology: Direct Fluorescent Antibody Stain

Use:

DFA identifies the infectious agent of a pneumonia

Panel includes influenza A and B, parainfluenza (1,2,3), RSV, adenovirus, human metapneumovirus (hMPV)

If DFA is negative or inadequate, a viral culture will be added

Limitations:

Adequacy of the direct specimen significantly influences the sensitivity of DFA

Inadequate specimen collection or too few cells on the slide may lead to failure of direct smears

Other viruses (eg, HSV, CMV) will not be routinely detected in this culture; decreased sensitivity for adenovirus using rapid culture

Sputum and nasal swabs are best specimens

Test name: Respiratory Virus Mini Panel by RT-PCR

ARUP #: 0060764

Methodology: Qualitative Reverse Transcription Polymerase Chain Reaction

Use:

Identify the infectious agent of a pneumonia

RT-PCR is a rapid and highly sensitive test for viruses; RT-PCR is also the most expensive test

Components include testing for influenza A and B and RSV

Additional Tests Available

Test name: Respiratory Syncytial Virus Antibody, IgM

ARUP #: 0051086

Methodology: Semi-Quantitative Enzyme-Linked Immunosorbent Assay

Comments:

Test name: Respiratory Syncytial Virus Antibody, IgG

ARUP #: 0051085

Methodology: Semi-Quantitative Enzyme-Linked Immunosorbent Assay

Comments:

Test name: Influenza A H1N1 (2009) Detection by RT-PCR

ARUP #: 2004217

Methodology: Reverse Transcription Polymerase Chain Reaction

Comments:

Detect the type novel H1N1 virus

General

ARUP Institute for Clinical and Experimental Pathology®

Comprehensive Review: October 2011
Last Update: October 2011

Adenovirus

Chlamydophila pneumoniae or psittaci

Parainfluenza Virus 1, 2, 3

Respiratory Viruses

Streptococcal Disease, Group A