Infection due to the human metapneumovirus is a common cause of acute respiratory tract infections.

Most infections occur in the winter and spring. Most children will have been exposed to this virus by age 5. Reinfections throughout life are possible, and infections occur in all age groups.

The human metapneumovirus can cause both upper and lower respiratory tract infections, and there are wide variations in clinical manifestations. On one end of the spectrum, patients have symptoms of the common cold. Patients with pneumonia may have severe infection and associated acute respiratory distress syndrome.

Children typically present with fever, cough, and rhinorrhea. Wheezing may be present. Rash may occur in some patients.

In adults, the symptoms of infection due to this organism are nonspecific, and similar symptoms may be seen due to infection with other respiratory viruses. Older patients with chronic cardiopulmonary disease who are infected with the human metapneumovirus are at increased risk of hospitalization.

Immunocompromised patients (especially following hematopoietic stem cell transplantation) are at increased risk of severe infection and respiratory failure due to this infection. In one review, patients who underwent hematopoietic stem cell transplantation and developed this infection presented with nonspecific symptoms including fever, cough, and nasal congestion.

Chest radiograph findings are nonspecific. Multilobar infiltrates and small pleural effusions may be seen.

Note: In 2022 and 2023, pediatric invasive group A streptococcal (iGAS) infections and noninvasive group A streptococcal infection cases were associated with respiratory infections due to human metapneumovirus, among other viruses. Concurrent or preceding viral infections, including varicella (chickenpox), may increase risk for iGAS infection. Severe outcomes of iGAS infections include necrotizing fasciitis, streptococcal toxic shock syndrome, and death.