Respiratory Syncytial Virus - RSV

Diagnosis

Indications for Testing

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

Laboratory Testing

  • Laboratory testing recommendations (CDC)
  • 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

Clinical Background

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 Laboratory Testing

  • Tests generally appear in the order most useful for common clinical situations
  • Click on number for test-specific information in the ARUP Laboratory Test Directory
Test Name and Number Recommended Use Limitations Follow Up
Respiratory Syncytial Virus DFA 0060288
Method: Direct Fluorescent Antibody Stain

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

Recommended for specimens other than CSF

   
Respiratory Syncytial Virus Antibodies, IgG & IgM (Temporary Referral as of 6/20/14) 0051087
Method: Semi-Quantitative Enzyme-Linked Immunosorbent Assay

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

 

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

Respiratory Viruses DFA with Reflex to Respiratory Virus Mini Panel by PCR 2002565
Method: Direct Fluorescent Antibody Stain/Qualitative Polymerase Chain Reaction

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

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

 
Respiratory Viruses DFA with Reflex to Viral Culture, Respiratory 0060281
Method: Direct Fluorescent Antibody Stain/Cell Culture

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

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

 
Respiratory Virus Mini Panel by PCR 0060764
Method: Qualitative Reverse Transcription Polymerase Chain Reaction

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
 
Click the plus sign to expand the table of additional tests.
Test Name and NumberComments
Respiratory Syncytial Virus Antibody, IgM (Temporary Referral as of 6/20/14) 0051086
Method: Semi-Quantitative Enzyme-Linked Immunosorbent Assay
Respiratory Syncytial Virus Antibody, IgG 0051085
Method: Semi-Quantitative Enzyme-Linked Immunosorbent Assay
Influenza A Virus H1/H3 Subtyping by Real-Time RT-PCR  2007469
Method: Qualitative Reverse Transcription Polymerase Chain Reaction

Identify H3 and 2009-H1 hemagglutinin genes

Current circulating influenza A strains are detected and typed (H1N1 and H3N2); however, other H1 and H3 subtypes may also be detected

Viral Culture, Respiratory 2006499
Method: Cell Culture

Viruses that can be isolated – adenovirus; CMV; enterovirus; HSV; influenza A and B; parainfluenza types 1, 2, and 3; RSV; and VZV

Virus-specific tests are recommended

Viral Culture, Respiratory and Cytomegalovirus Rapid Culture 2006497
Method: Cell Culture/Immunofluorescence

Viruses that can be isolated – adenovirus; CMV; enterovirus; HSV; influenza A and B; parainfluenza types 1, 2, and 3; RSV; and VZV

Virus-specific tests are recommended