What is the recommended treatment for a patient diagnosed with human metapneumovirus (hMPV)?

Treatment of Human Metapneumovirus (hMPV)

For immunocompetent adults with hMPV infection, provide supportive care only, as no antiviral agent has established efficacy for treating hMPV. 1

Immunocompetent Patients

The mainstay of therapy for otherwise healthy individuals consists of rest, hydration, and symptomatic management 1. Treatment is entirely supportive because hMPV infections are typically mild and self-limiting in this population 2.

Specific Supportive Measures

• Oxygen therapy: Titrate to maintain adequate saturation 1
• Monitoring: Track vital signs, oxygen saturation, and respiratory status continuously 1
• Fluid and electrolyte management: Maintain appropriate balance 1
• Bacterial superinfection: Treat if suspected or documented with appropriate antibiotics 1
• Nutritional support: Provide high-protein, high-vitamin, carbohydrate-containing diets 3

Immunocompromised Patients and Severe Disease

For immunocompromised patients with lower respiratory tract disease from hMPV, consider treatment with ribavirin and/or intravenous immunoglobulin (IVIG), despite the lack of randomized controlled trial data. 1

When to Consider Antiviral Therapy

• Hematopoietic stem cell transplant (HSCT) recipients with pneumonia or lower respiratory tract involvement 1
• Leukemia patients with lower respiratory tract disease 1
• Patients with severe disease requiring hospitalization 4

Important caveat: Upper respiratory tract infection alone in immunocompromised patients does not typically warrant antiviral therapy 1. The decision to treat should be based on progression to lower respiratory tract involvement.

Treatment Regimen for Severe Cases

When treatment is pursued in immunocompromised patients:

• Ribavirin: Can be administered orally or via aerosolization 4
• IVIG: Given in combination with ribavirin 4
• Duration: Continue until clinical improvement is documented 4

Case series have shown successful outcomes with this combination in immunocompromised patients with severe hMPV pneumonia 4.

Risk Factors Requiring Closer Monitoring

• Early post-HSCT period: Particularly high risk for progression to severe disease 1
• Higher corticosteroid exposure: Associated with increased risk of severe outcomes 1
• Neutropenia and lymphopenia: Independent risk factors for severe disease 1

Advanced Respiratory Support

For patients developing moderate to severe ARDS from hMPV:

• High-flow nasal oxygen (HFNO) or non-invasive ventilation (NIV) as initial escalation 3
• Invasive mechanical ventilation with prone positioning for severe ARDS 3
• Veno-venous ECMO: Consider as rescue therapy for refractory, life-threatening hypoxemia despite maximal medical support 5

Infection Control Measures

Implement standard and droplet precautions to prevent nosocomial transmission. 1

Key Infection Control Considerations

• Prolonged viral shedding: Documented in HSCT patients, requiring extended precautions 1, 6
• Asymptomatic shedding: Substantial rates in immunocompromised populations 1
• Isolation duration for immunocompetent patients: Minimum 5-7 days from symptom onset or until symptoms resolve, whichever is longer 6
• Isolation duration for immunocompromised patients: Extended isolation for 10-14 days or longer due to prolonged shedding 6

Practical Infection Control Steps

• Patient masking: Medical masks when around others 6
• Caregiver protection: N95 or surgical masks when in the same room 6
• Environmental disinfection: Clean frequently touched surfaces with 500 mg/L chlorine-containing disinfectant daily 6

Critical Pitfalls to Avoid

• Do not overlook coinfections: hMPV is frequently codetected with other pathogens in pneumonia cases, which complicates treatment decisions and may require broader antimicrobial coverage 1, 6
• Do not treat upper respiratory tract infection alone in immunocompromised patients: Reserve ribavirin/IVIG for documented lower respiratory tract involvement 1
• Do not assume immunity after infection: Reinfections are common throughout life due to transient immunity 2
• Do not rely on viral culture for diagnosis: Molecular methods such as RT-PCR are the preferred diagnostic modality due to slow viral growth in culture 2, 7

Current Treatment Limitations

No vaccine is currently available for hMPV, and no general recommendation for antiviral treatment can be made based on available evidence for the general population 1, 2. Single cases of severe disease and fatal outcomes have been reported even with treatment attempts using ribavirin and IVIG 1. The evidence supporting ribavirin/IVIG use remains limited to case series and expert opinion rather than randomized controlled trials 1, 4.