What is the treatment for human metapneumovirus in patients with varying severity of illness and underlying medical conditions?

Treatment of Human Metapneumovirus

For immunocompetent patients with human metapneumovirus (hMPV) infection, provide supportive care only—no antiviral therapy is indicated. 1

Immunocompetent Adults and Children

Supportive care is the sole recommended treatment for otherwise healthy individuals with hMPV infection. 1 This approach is endorsed by the American College of Physicians and the Infectious Diseases Society of America, as no antiviral agent has established efficacy for hMPV treatment. 1

Specific Supportive Measures

• Rest and hydration form the foundation of management. 1
• Fever control with acetaminophen using weight-based dosing. 2
• Nasal congestion relief with normal saline nasal drops and gentle suctioning. 2
• Oxygen therapy titrated to maintain adequate saturation (≥92%). 1
• Monitor vital signs, oxygen saturation, and respiratory status continuously. 1
• Fluid and electrolyte management to prevent dehydration, especially in infants. 2

What NOT to Do

• Do not prescribe antibiotics unless bacterial superinfection is documented (e.g., acute otitis media with purulent features or bacterial pneumonia with clinical and radiological confirmation). 2 No clinical or radiographic criteria reliably distinguish hMPV from bacterial infection, but antibiotics should only be used when bacterial coinfection is confirmed. 3
• Do not use over-the-counter cough and cold medications in children under 4 years of age. 2

Expected Clinical Course

• Most patients recover within 7-10 days with supportive care alone. 2
• Cough may persist for 2-3 weeks even after other symptoms resolve. 2

Immunocompromised Patients and Severe Disease

For immunocompromised patients with hMPV lower respiratory tract disease, consider treatment with ribavirin and/or intravenous immunoglobulin (IVIG), despite the lack of randomized controlled trial data. 1 This recommendation comes from the Centers for Disease Control and Prevention and is specifically endorsed by the American Society of Hematology for hematopoietic stem cell transplant (HSCT) recipients and leukemia patients with pneumonia or lower respiratory tract involvement. 1

When to Consider Antiviral Therapy

• Lower respiratory tract disease (pneumonia, bronchiolitis) in immunocompromised patients warrants consideration of ribavirin ± IVIG. 1, 2
• Upper respiratory tract infection alone in immunocompromised patients does not typically warrant antiviral therapy. 1
• HSCT recipients, particularly early post-transplant, are at highest risk for progression to severe disease with 10-30% mortality. 3

High-Risk Populations Requiring Close Monitoring

• Hematopoietic stem cell transplant recipients, especially early post-transplant. 1, 3
• Patients with higher corticosteroid exposure. 1
• Patients with neutropenia and lymphopenia. 1
• Patients with chronic cardiac or pulmonary diseases. 3

Evidence Limitations

The American College of Physicians notes that no general recommendation for antiviral treatment can currently be made based on available evidence. 1 While ribavirin has shown in vitro activity against hMPV, its clinical efficacy has not been proven in randomized trials. 2, 4 The Society for Healthcare Epidemiology of America reports that fatal outcomes have occurred even with treatment attempts. 1

Critical Warning Signs Requiring Immediate Medical Attention

In Infants and Children

• Respiratory distress: oxygen saturation <92%, respiratory rate >70 breaths/min, grunting, intercostal retractions, or increased work of breathing. 2
• Poor feeding or refusal to feed. 2
• Signs of dehydration: decreased urine output, dry mouth, or no tears when crying. 2
• Altered mental status: excessive sleepiness, difficulty waking, or excessive irritability. 2
• Worsening symptoms or no improvement after 48 hours. 2

In Severe Cases

• Progression to respiratory failure unresponsive to conventional oxygen therapy. 3
• Septic shock, metabolic acidosis, and coagulation dysfunction. 3

Infection Control Measures

Implement standard and droplet precautions to prevent nosocomial transmission, as hMPV demonstrates asymptomatic and prolonged shedding, particularly in HSCT patients. 1 The estimated incubation period is 2.6 days, and nosocomial outbreaks can occur given high rates of asymptomatic shedding. 1

Common Pitfalls to Avoid

• Do not assume bacterial infection based on clinical presentation alone—hMPV cannot be reliably distinguished from bacterial pneumonia clinically or radiographically. 3 However, maintain a low threshold for empirical antibiotics only in severe cases with high clinical suspicion of bacterial superinfection. 1, 3
• Do not overlook coinfection: hMPV is frequently codetected with other pathogens (especially RSV), which complicates treatment decisions and obscures attributable morbidity. 1, 3
• Do not use ribavirin routinely: It should only be considered for severe lower respiratory tract disease in immunocompromised patients, not for mild disease or immunocompetent patients. 1, 2