Respiratory Syncytial Virus I... Health Article

Definition

Respiratory syncytial virus (RSV) is a virus that can cause severe lower respiratory infections in children younger than two years of age and milder upper respiratory infections in older children and adults. RSV infection in young children is also called bronchiolitis, because it is marked by inflammation of the bronchioles, the narrow airways that lead from the large airways (bronchi) to the tiny air sacs (alveoli) in the lungs. The symptoms include wheezing, difficulty breathing, and sometimes respiratory failure.

Description

RSV infection is caused by a group of viruses found worldwide. There are two different subtypes of the virus with numerous different strains. Taken together, these viruses account for a significant number of deaths in infants.

RSV infection shows distinctly different symptoms, depending on the age of the infected person. In young children, the virus causes a serious lower respiratory infection in the lungs. In older children and healthy adults, it causes a mild upper respiratory infection often mistaken for the common cold.

Although anyone can get this disease, infants suffer the most serious symptoms and complications. Breast-feeding seems to provide partial protection from the virus. Conditions in infants that increase their risk of infection include:

• premature birth
• lower socio-economic environment
• congenital heart disease
• chronic lung diseases, such as cystic fibrosis
• immune system deficiencies, including HIV infection
• immunosuppressive therapy, such as that given to organ transplant or cancer patients

Many older children and adults get RSV infection, but the symptoms are so similar to the common cold that the true cause is undiagnosed. People of any age with compromised immune systems, either from such diseases as AIDS or leukemia, or as the result of chemotherapy or corticosteroid medications, and patients with chronic lung disease are more at risk for serious RSV infections.

Demographics

RSV infection is primarily a disease of winter or early spring, with waves of illness sweeping through a community. The rate of RSV infection is estimated to be 11.4 cases for every 100 children during their first year of life. In the United States, RSV infection occurs most frequently in infants between the ages of two months and six months.

Respiratory syncytial virus is spread through close contact with an infected person. It has been shown that if a person with RSV infection sneezes, the virus can be carried to others within a radius of 6 feet (1.8 m). This group of viruses can live on the hands for up to half an hour and on toys or other inanimate objects for several hours.

Scientists had, as of 2004, not understood why RSV viruses attack the lower respiratory system in infants and the upper respiratory system in adults. In infants, RSV begins with such cold symptoms as a low fever, runny nose, and sore throat. Soon, other symptoms appear that suggest an infection that involves the lower airways. Some of these symptoms resemble those of asthma. RSV infection is suggested by the following characteristics:

• wheezing and high-pitched, whistling breathing
• rapid breathing (more than 40 breaths per minute)
• shortness of breath
• labored breathing out (exhalations)
• bluish tinge to the skin (cyanosis)
• croupy, seal-like, barking cough
• high fever

Breathing problems occur in RSV infections because the bronchioles swell, making it difficult for air to get in and out of the lungs. If the child is having trouble breathing, immediate medical care is needed. Breathing problems are most common in infants under one year of age; they can develop rapidly.

Physical examination and imaging studies

RSV infection is usually diagnosed during a physical examination by the pediatrician or primary care doctor. The doctor listens with a stethoscope for wheezing and other abnormal lung sounds in the patient's chest. The doctor will also take into consideration whether there is a known outbreak of RSV infection in the area. Chest x rays give some indication of whether the lungs are hyperinflated from an effort to move air in and out. X rays may also show the presence of a secondary bacterial infection, such as pneumonia.

Laboratory tests

A nasal swab can be obtained to isolate the virus or antibodies to the virus in secretions. If infants are hospitalized, other tests such as an arterial blood gas analysis are done to determine if the child is receiving enough oxygen.