Study: Asthma Caused by Respiratory Infections

Severe respiratory viral infections in young children are much more likely to develop asthma, but new research from the Washington University School of Medicine in St. Louis could one day prevent viral infections from causing asthma. By identifying the process that causes asthma after having a severe respiratory viral infection in mice, researchers believe they may be able to stop the process in children.

The researchers found that instead of developing antibodies to react to an infection, children with a severe respiratory viral infection developed a response that indicated an allergy. This creation of the wrong type of antibodies started a chain reaction that eventually led to the development of asthma in some children.

"We think genetically predisposed individuals will tend to have this kind of immune reaction to a severe respiratory viral infection," says the study's lead author Mitchell Grayson, M.D., assistant professor of medicine in the Division of Allergy and Immunology in a press release. "In those people an allergic-type response could be part of their antiviral immune response. That sets them up to make antibodies against a lot of environmental substances, like pet dander or pollen, and they can go on to develop allergies or asthma."

Severe respiratory viral infections are common in young children. The respiratory syncytial virus often causes infections. Most children under the age of four have had a severe respiratory viral infection at least once. A severe case can cause coughing, wheezing and gasping for breath, and can cause the need for hospitalization.

In the mice used the in study, researchers were able to prevent asthma by altering the response of the immune cells to a respiratory infection. Researchers believe that a medication taken after contracting a severe respiratory viral infection could lessen the chances of developing asthma, cutting the growing number of children who have asthma significantly.

"A severe respiratory infection in infancy greatly increases the risk of developing asthma," said Grayson. "Less than one in 30 people who don't suffer a severe respiratory infection as a baby develop asthma, but of those who do get these infections, one in five goes on to have asthma."

Asthma continues to be a growing area of concern in the United States. According to the Centers for Disease Control and Prevention, the amount of people with asthma increased by 13 million people between 1980 and 2003. Although researchers are unsure why the trend exists, the rapid increase further emphasizes the need to prevent asthma when possible.

Source:

Washington University in St. Louis, "Blocking effects of viral infections may prevent asthma in young children" Eurekalert