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Medical Author:

John Mersch, MD, FAAP

John Mersch, MD, FAAP

Dr. Mersch received his Bachelor of Arts degree from the University of California, San Diego, and prior to entering the University Of Southern California School Of Medicine, was a graduate student (attaining PhD candidate status) in Experimental Pathology at USC. He attended internship and residency at Children's Hospital Los Angeles.

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Medical Editor:

Mary D. Nettleman, MD, MS, MACP

Mary D. Nettleman, MD, MS, MACP

Mary D. Nettleman, MD, MS, MACP is the Chair of the Department of Medicine at Michigan State University. She is a graduate of Vanderbilt Medical School, and completed her residency in Internal Medicine and a fellowship in Infectious Diseases at Indiana University.

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In this Article

• Respiratory syncytial virus (RSV) infection facts
• What is the respiratory syncytial virus (RSV)?
• When does RSV infection occur, and who gets it?
• Who is at risk for severe disease?
• Is RSV infection contagious, and how is RSV infection transmitted?
• What are the symptoms of RSV infection?
• How is RSV infection diagnosed?
• What is the treatment for an RSV infection?
• How can RSV infection be prevented?
• Is there an RSV vaccine?
• What is the prognosis of a respiratory syncytial virus infection?
• Find a local Pediatrician in your town
• Respiratory Syncytial Virus Index

Infection with RSV is seasonal. In temperate climates, RSV infections usually occur during the late fall, winter, or early spring months. Annual community outbreaks of RSV infection often last four to five months. The winter season (November through April) tend to be most likely to experience RSV epidemic disease. For unknown reasons, severity of illness and frequency of disease often alternate on an annual basis. For example: a "bad" year (large number of patients with moderately severe disease) is followed by a "good" year (fewer number of patients with less severe disease).

More than half of all infants are exposed to RSV by their first birthday. Many have few or mild symptoms. However, some babies with RSV become very ill. RSV is the most common cause of bronchiolitis and pneumonia among infants and children under 1 year of age.

After childhood, RSV causes repeated infections throughout life. These infections are usually associated with cold-like symptoms. However, severe lower respiratory tract disease (for example, wheezing and/or pneumonia) may occur at any age, especially among the elderly or among those with compromised cardiac, pulmonary, or immune systems.

Several broad categories of patients are most vulnerable to RSV infection. These include: (a) premature infants and all infants less than 1 year of age, (b) children < 2 years old with cardiac disease or chronic lung disease (for example, asthma, cystic fibrosis, etc.), (c) those of any age with a compromised immune system, and (d) those 65 years of age or older.

RSV disease is very highly contagious. Annually 75,000-125,000 babies less than 1 year old require hospitalization. Of those infants hospitalized, approximately 1%-2% die (750-1,500 children). The RSV incubation period (time between exposure and development of symptoms) is two to eight days. It is spread via respiratory secretions through close contact with infected people or contact with contaminated surfaces or objects. Infection can occur when infectious particles contacts mucous membranes of the eyes, mouth, or nose, and possibly through the inhalation of droplets generated by a sneeze or cough. Those who develop RSV are contagious during the first three to eight days of their illness.