The virus invades the cells lining the respiratory tract, producing large amounts of mucus and airway swelling. Since infants and toddlers have small bronchiole tubes, the virus can cause a serious illness if the swelling plugs their tiny airways. In the worst cases, the infant’s breathing tubes can collapse from the intense effort it takes to breathe around the swelling. The virus is especially dangerous when the youngster is less than one year old or has asthma. Youngsters born prematurely, those with other lung disorders (such as cystic fibrosis) and those with congenital heart disease are also at risk should they develop an RSV infection. Thankfully, the virus rarely causes problems in the first six weeks of a child’s life, since these babies still have antibodies from their mothers.

The time from exposure to the onset of symptoms is usually about four days. The highest rates of RSV illness occur in youngsters less than one year of age. The virus is often carried home by a school-aged child and passed onto a younger sibling, especially an infant. RSV is spread by airborne particles dispersed when someone infected coughs or, when the child touches someone or something (such as a toy or pacifier) infected with the RSV. Once one child in a daycare or preschool is infected, RSV quickly spreads to other youngsters since a child is infectious before symptoms appear. Furthermore, an infected child can remain contagious one to three weeks after their symptoms disappear.

A small child infected with RSV first develops a runny nose and a red throat, which gradually progresses to include a cough, wheezing, and sometimes a fever. In most babies, this is as severe as RSV gets and these symptoms usually last five to 12 days. Unfortunately, some will get worse and exhibit fast respirations (> 40 per minute), difficulty breathing, and listlessness. Other danger signs include a bluish discoloration of the skin around the mouth, nasal flaring, retractions between the ribs, and reduced fluid intake to the point of dehydration. RSV is diagnosed by checking for antibodies to the virus in nasal washing, or growing the virus from a nose swab.

Treatment is designed to make the child feel comfortable until their own antibodies control the virus. Using a cool-mist vaporizer to humidify the air will soothe irritated breathing passages and relive coughing. Giving plenty of fluids helps loosen secretions so that the child can clear them easily. Fever is best treated with acetaminophen and ibuprofen. If the child is too young to blow their nose, a nasal aspirator and salt water nose drops can be used to remove the thick nasal secretions. Medications that dilate the bronchiole tubes are occasionally prescribed to help relieve chest congestion and wheezing. While antibiotics have no effect on RSV, hospitalized children are often given an anti-viral medication called ribavirin by aerosol.

There is no vaccine yet available to prevent RSV infection in small children although one is being developed. However, there are some things parents can do to minimize the chances that their youngster will get sick from RSV.

*No smoking in the home of a child suspected of an RSV infection. Almost all children hospitalized with RSV come from a home where someone smokes.

*Whenever a school age child comes down with a "cold," keep them away from an infant brother or sister until the infection passes.

*The best way to prevent RSV is good handwashing, particularly just before handling susceptible infants. Siblings, parents, and daycare providers should use a tissue when they cough or sneeze.

*Toys should be washed, especially if other children have played with them

*RSV is rampant in day care centers, so having a child in a home setting can decrease the infection risk.

Children who are sick enough to see a physician because of RSV have a 33%-50% chance of developing recurrent wheezing (asthma) later in life. This is even more likely if the child has eczema or if there is asthma in the family. It is not known whether the virus damages the respiratory system and causes the asthma, or it is the youngster’s susceptibility to asthma that predisposes them to severe RSV.