RSV (Respiratory Syncytial Virus) Infection
RSV (Respiratory Syncytial Virus) Infection
Disease History, Characteristics, and Transmission
Introduction
Respiratory Syncytial virus (RSV) is a ribonucleic acid (RNA)-containing virus that causes a lung infection (pneumonia) that affects the oxygenand carbon dioxidecarrying tubes called the bronchioles. These tubes are very tiny and are located deep within the lungs. Because of this, the infection, which is also known as bronchiolitis, can hamper the function of the lungs.
RSV infections can be spread easily from person-toperson and can occur repeatedly in infants. Indeed, RSV infections are the most common cause of bronchiolitis and pneumonia in newborns and infants under one year of age.
Disease History, Characteristics, and Transmission
The first symptoms of an RSV lung infection are often mistaken for a cold. A child can have a fever and a runny nose. The involvement of the lungs can be evident as a cough and sometimes a wheezing type of breathing.
A lung infection that involves the bronchioles may not occur the first time someone is infected by RSV. However, up to 40% of infants do experience the more severe lung infection; this can require hospitalization, especially in infants under six months of age.
Most children recover from the infection within a few weeks. However, repeated cold-like infections can then occur throughout life. In addition, the lung infection can be more serious, especially in elderly people or those whose immune systems are less capable of fighting off infections.
The virus is spread in the tiny drops of mucus and other fluids that are expelled from the nose during a sneeze and from the lungs when someone coughs. If another person is close by, these drops can be inhaled and the virus may then be able to establish an infection in the new host. Alternatively, the virus-laden droplets can land on inanimate objects such as a doorknob or can be transferred to a hand when the nose is wiped. Touching an object before the hands are washed can also transfer the virus. If the contaminated object is touched within a few hours, the virus can picked up on the hands and transfer to the new host can occur.
This route of transmission makes RSV infection especially prevalent in more northern climates during colder months when people are indoors more often and the chances of person-to-person spread is greater. This sort of a pattern is known as a community outbreak. Illness in warmer climates shows less of a seasonal pattern.
WORDS TO KNOW
ATTENUATED STRAIN: A bacterium or virus that has been weakened, often used as the basis of a vaccine against the specific disease caused by the bacterium or virus.
BRONCHIOLITIS: Inflammation (-itis) of the bronchioles, the small air passages in the lungs that enter the alveoli (air sacs), is bronchiolitis.
Scope and Distribution
RSV infection tends to be more prevalent in climates that have colder seasons, since people are in closer indoor contact for part of the year. However, the infection can occur virtually anywhere. Because infants and the elderly are the most susceptible, RSV infection is associated with hospitals, daycare centers, and retirement or elder-care settings.
Treatment and Prevention
Spread of RSV can be minimized or even prevented by common-sense hygiene. Covering the nose and mouth with a tissue when sneezing or coughing can prevent the spread of virus-laden droplets in the air. Washing the hands with regular hand soap will inactivate any RSV on the skin.
The presence of the virus can be detected by isolation of the virus. In addition, molecular techniques can be used to detect protein components of the virus by the presence of antibodies to these proteins (antibodies are proteins produced by the immune system in response to the presence of a component that is foreign to the host) and by the presence of viral genetic material. These tests are fairly specialized and require trained staff and a laboratory with the necessary equipment. Tests to monitor the antibody levels are the more common molecular approach.
Diagnosis is usually confirmed only for severe illnesses in hospitalized patients. For most people who have RSV infection, no specific treatment is administered, since the illness is limited. In infants and children, treatment typically is aimed at reducing the discomfort due to fever, and acetaminophen is most commonly used for this purpose.
More severe disease can require the use of supplemental oxygen or even mechanical ventilation (when a tube is inserted down the patient's trachea to deliver oxygen directly to the lungs), since the lungs may not be functioning efficiently. Antiviral drugs such as ribavirin are also administered. The drug is structurally similar to the viral RNA and so can interfere with the process used by the virus to make new copies of itself.
Another treatment option for more severe RSV infection is the use of immune globulin, a compound produced by the immune system. This strategy is especially useful for people whose own immune systems are malfunctioning and so not as capable of producing the compound. Immune globulin is usually given intravenously.
Impacts and Issues
The fact that RSV infections predominantly affect the very young and the elderly makes it a concern for these age groups. In some cases, lung function can be affected by RSV infection to the point that hospitalization and mechanical breathing assistance is necessary. In the United States, about 80,000 children are hospitalized with RSV infections every year.
Almost half of otherwise healthy babies who are hospitalized with RSV develop asthma later in childhood. Asthma is the number one reason for school absences in children due to a chronic illness, resulting in about 14 million lost school days per year in the United States. In several studies, researchers are tracking healthy newborns who develop RSV as they grow to determine genetic and environmental factors that may link RSV with asthma.
RSV infections also highlight the potential for an infectious disease to spread more easily in a crowded indoor environment and the importance of commonsense hygiene. Such hygienic measures as cleaning toys and equipment in daycare centers and frequent handwashing can help to significantly minimize the risk of infection.
Efforts are ongoing to develop a vaccine against RSV. Researchers at Vanderbilt University are pursuing one approach that involves using genetic technologies to manipulate genes in the RSV virus. By causing small mutations or deletions in the genes of the virus, an improved attenuated (weakened) form of the RSV virus is produced that could lead to the development of a safe, efficient vaccine. As of 2007, a vaccine for RSV is not yet available.
See AlsoPublic Health and Infectious Disease.
BIBLIOGRAPHY
Books
Cane, Patricia, ed. Respiratory Syncytial Virus. Vol. 14 of Perspectives in Medical Virology. New York: Elsevier Science, 2006.
Hart, Tony. Microterrors: The Complete Guide to Bacterial, Viral and Fungal Infections That Threaten Our Health. Tonawanda, NY: Firefly Books, 2004.
Sears, William, and Martha Sears. The Baby Book: Everything You Need to Know About Your Baby from Birth to Age Two. New York: Little, Brown, 2003.
Web Sites
Centers for Disease Control and Prevention. “Respiratory Syncytial Virus.” January 1, 2005. <http://www.cdc.gov/ncidod/dvrd/revb/respiratory/rsvfeat.htm> (accessed March 1, 2007).
Brian Hoyle