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

• RSV
• Influenza
• Parainfluenza virus 1, 2, 3
• Mycoplasma pneumoniae
• Legionella pneumophila
• Chlamydophila pneumoniae or psittaci
• Adenovirus
• Hantavirus
• Bocavirus
• Enterovirus
• Severe acute respiratory syndrome

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

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

General

• Broor S, Bharaj P, Chahar HS. Human metapneumovirus: a new respiratory pathogen. J Biosci. 2008; 33 (4) :483-493.PubMed
• Deffrasnes C, Hamelin ME, Boivin G. Human metapneumovirus. Semin Respir Crit Care Med. 2007; 28 (2) :213-221.PubMed
• Don M, Canciani M, Korppi M. Community-acquired pneumonia in children: what's old? What's new?. Acta Paediatr. 2010; 99 (11) :1602-1608.PubMed
• Hustedt JW, Vazquez M. The changing face of pediatric respiratory tract infections: how human metapneumovirus and human bocavirus fit into the overall etiology of respiratory tract infections in young children. Yale J Biol Med. 2010; 83 (4) :193-200.PubMed
• Kahn JS. Newly identified respiratory viruses. Pediatr Infect Dis J. 2007; 26 (8) :745-746.PubMed
• Ruuskanen O, Lahti E, Jennings LC, Murdoch DR. Viral pneumonia. Lancet. 2011; 377 (9773) :1264-1275.PubMed
• Walsh EE, Peterson DR, Falsey AR. Human metapneumovirus infections in adults: another piece of the puzzle. Arch Intern Med. 2008; 168 (22) :2489-2496.PubMed

Adenovirus
Bordetella pertussis
Chlamydophila pneumoniae or psittaci
Influenza Virus
Legionella pneumophila
Mycoplasma pneumoniae
Parainfluenza Virus 1, 2, 3
Respiratory Syncytial Virus
Respiratory Viruses