Rise in asthma hospitalizations coincides with start of school year

A rise in asthma exacerbations and hospitalizations in the fall is related to the start of school and a subsequent increase in viral infections among children. Attempting to improve asthma control and reduce the transmission of infections as school starts could reduce the annual September asthma epidemic, according to research published in the March 2006 issue of the Journal of Allergy and Clinical Immunology (JACI).

Neil W. Johnston, MSc, of St. Joseph's Healthcare and McMaster University, Hamilton, Ontario, and colleagues undertook a study to determine the sequence of timing for September asthma hospitalization epidemics in children and adults, and to determine whether school-age children transmit the viral infections that often lead to asthma attacks in adults. To make this determination, they looked at admission data for Canadian hospitals between 1990 and 2002; subjects were divided into three age groups: school-age children (5 through 15 years old); preschool children (ages 2 through 4 years); and a subset of adults (16 to 49 years old).

Among the investigators' findings:

• On average, the epidemic peak for school-age children was 17.7 days after Labor Day (the day, or two days, after the holiday is traditionally the beginning of the school year), 19.4 days after Labor Day for preschool children, and 24 days after Labor Day for adults

• Timing of the asthma exacerbation peak, from north to south, was also consistent with differences in weather conditions and in-school allergen levels

• The sequence of the epidemic remained consistent-suggesting that viral infections were transferred from the school-age children to the preschool children and adults with whom they were in contact

• School-age children were the starting point for the viruses, with children ages 5 to 7 the leading group affected by the asthma epidemic; researchers propose that this could be the case because they are not as resistant to the infections and because infections transmit easily from children to other children or adults because of children's social behavior

• Rhinovirus infections are the leading cause of respiratory infection among children in the early fall; between 80 to 85% of children with wheezing episodes test positive, and half of adults with a wheezing episode also have a rhinovirus infection

The investigators conclude that finding ways to prevent respiratory infection in children is a key component in attempt to reduce the severity of the annual asthma outbreak-among all ages.

The study, "The September epidemic of asthma hospitalization: School children as disease vectors," can be found on JACI's Web site, www.jacionline.org. The JACI is the peer-reviewed, scientific journal of the American Academy of Allergy, Asthma, and Immunology (AAAI).