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Respiratory Syncytial Virus (RSV) Infection and Human Metapneumovirus Infection

By Mary T. Caserta, MD, Professor of Pediatrics, Division of Infectious Diseases, University of Rochester School of Medicine and Dentistry; Attending Physician, Golisano Children’s Hospital at Strong, University of Rochester Medical Center

Respiratory syncytial virus infection and human metapneumovirus infection cause upper and sometimes lower respiratory tract infections.

  • Respiratory syncytial virus is a very common cause of respiratory infections in infants and young children.

  • Human metapneumovirus is similar to respiratory syncytial virus but is a separate virus.

  • Typical symptoms include a runny nose, fever, cough, and wheezing, and a severe infection can lead to respiratory distress.

  • The diagnosis is based on symptoms and their occurrence at expected times of year.

  • Palivizumab is given to children at high risk of developing a severe respiratory syncytial virus infection.

  • Oxygen is given as needed.

Respiratory syncytial virus (RSV) is a very common cause of respiratory tract infection, particularly in children. Nearly all children have been infected by age 4 years, many in the first year of life. Infection does not provide complete immunity, so reinfection is common, although usually less serious. Outbreaks typically occur in winter and early spring. RSV is the most common cause of lower respiratory tract illness in young infants and is responsible for more than 50,000 hospitalizations every year in the United States in children under the age of 5 years.

The first infection often progresses from an upper respiratory tract illness with congestion and fever to involve the lower respiratory tract, most commonly causing bronchiolitis and sometimes pneumonia with cough and difficulty breathing. Later infections usually involve only the upper respiratory tract. Children who have had bronchiolitis have an increased risk of developing asthma when they are older.

Children with serious underlying disorders (such as congenital heart disease, asthma, cystic fibrosis, or immune system suppression) or who were born prematurely, and infants under 3 months of age are at particular risk of developing serious illness. Adults and older children also can be infected with RSV, and the elderly may develop pneumonia.

Human metapneumovirus (hMPV) is a similar but separate virus. hMPV occurs at the same time seasonal time as RSV but does not infect as many children.


RSV and hMPV cause similar symptoms. A runny nose and fever begin 3 to 5 days after infection. About half of children with a first infection also develop a cough and wheezing, indicating lower respiratory tract involvement. In infants younger than 6 months old, the first symptom may be a period of not breathing (apnea). Some children, usually young infants, develop severe respiratory distress, and a few die. In healthy adults and older children, illness is usually mild and may manifest only as a common cold.


  • A doctor's evaluation

Doctors usually suspect RSV (and possibly hMPV) infection in young infants and children who have bronchiolitis or pneumonia during RSV season or during an outbreak. Tests are usually not done unless doctors are trying to identify an outbreak or if hospitalization is required. When necessary, samples of nasal secretions are sent for a rapid antigen test or the polymerase chain reaction (PCR) technique.


There is no vaccine to prevent RSV or hMPV infection.

Doctors may give monthly injections of palivizumab, which contains antibodies against RSV, to children who are at high risk of developing a severe RSV infection. High-risk children include young children who have serious heart or lung disease and/or who are very premature. The injections are given for the length of the RSV season.

Children who receive palivizumab are less likely to need hospitalization, but doctors are not sure whether this treatment prevents death or serious complications.


  • Oxygen for breathing difficulty

Children who have difficulty breathing are taken to a hospital. Depending on their condition, doctors may treat them with oxygen and fluids by vein. Ribavirin, an antiviral drug, is no longer recommended except for children whose immune system is severely weakened.

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