Metapneumovirus - hMPV

Diagnosis

Indications for Testing

  • Immunocompromised patients, older adults, and children with severe respiratory illness

Laboratory Testing

  • Collection of high-quality, cellular respiratory specimen required for best results
  • Direct fluorescent antibody (DFA) staining – most rapid and useful test
  • Polymerase chain reaction – most sensitive test
    • Use to confirm negative DFA in cases with suspicion
  • Culture – not recommended because organism cannot be isolated from conventionally used cell lines
  • Consider concurrent viral testing for influenza, RSV, adenovirus, bocavirus
    • May also consider testing for atypical pneumonia agents – Mycoplasma pneumoniae, Chlamydophila pneumoniae

Differential Diagnosis

Clinical Background

The human metapneumovirus (hMPV) is a recently (2001) discovered agent of viral respiratory infections.

Epidemiology

  • Prevalence – accounts for 5-10% of respiratory infections in hospitalized children and 10-20% of infections in outpatient clinics
  • Age – usually in children <10 years
    • By 5 years, nearly all children show evidence of past infection
  • Occurrence – peak season November through May
  • Transmission – airborne droplet

Organism

  • Single-stranded RNA virus
  • Member of the Paramyxoviridae family
  • Strains A and B concurrent
  • Reinfection circulate possible

Risk Factors

  • Age – children <10, adults >55
  • Compromised immune system
  • Chronic medical condition (cardiac, pulmonary, hepatic)

Clinical Presentation

  • Clinical symptoms indistinguishable from respiratory syncytial virus (RSV)
  • Symptoms range from common cold to severe lower respiratory tract infections such as bronchitis and pneumonia
  • Usual symptoms include coughing/wheezing, hypoxia, fever
  • May exacerbate asthma and may play an etiological role in its development
  • Coinfection with RSV and adenovirus common and usually associated with more severe disease

Treatment

  • Supportive

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
Human Metapneumovirus by DFA  0060779
Method: Direct Fluorescent Antibody Stain

Use to detect all types of hMPV (A1, A2, B1, B2)

No cross reactivity with other common respiratory viruses

Sample requires adequate amount of intact cells

  
Human Metapneumovirus by RT-PCR 0060784
Method: Qualitative Polymerase Chain Reaction

Use to detect all types of hMPV (A1, A2, B1, B2)

Confirm a negative DFA test when infection from hMPV is highly suspected

Negative result does not rule out the presence of PCR inhibitors in the patient specimen or human metapneumovirus nucleic acid concentrations below the level of assay detection

  
Additional Tests Available
 
 
Click the plus sign to expand the table of additional tests.
Test Name and NumberComments
Respiratory Viruses DFA with Reflex to Viral Culture, Respiratory 0060281
Method: Direct Fluorescent Antibody Stain

Rapid test to identify common agents in respiratory infections; if negative, reflexes to viral culture

Tests for adenovirus, influenza A and B, parainfluenza, respiratory syncytial virus, and human papillomavirus
Viral Culture, Respiratory 2006499
Method: Cell Culture