Asthma is a respiratory condition characterized by an inflammation of the airways. For unknown reasons, the airways of a person with asthma become over-sensitive to certain stimuli, like allergens, irritants or infections.

The air passages swell and the muscles surrounding the bronchial tubes tighten, causing the airways to narrow further. In addition, production of thick mucus in the airways causes them to clog.

During an asthma attack, a patient may experience coughing, wheezing, chest tightness, shortness of breath and rapid breathing. Narrowing and constriction of the airways reduces the ability of the lungs to get oxygen. In severe cases, patients may collapse from a lack of oxygen or even die.

Asthma is one of the most common chronic diseases in children. The American Academy of Allergy Asthma and Immunology estimates 20 million Americans have asthma. About nine million are children. Asthma is the most common cause of school absences due to chronic disease, causing about 12.8 million lost days from school each year. About 5,000 people die from asthma annually.

Looking for Asthma Clues

Studies show children living in cities tend to have higher rates of asthma compared to those living in rural areas. Researchers from the Medical College of Wisconsin recently completed a survey to further investigate and compare asthma rates among rural children. The investigators found children who lived on a farm had lower rates of asthma than children who were not living on a farm. The seemingly protective effect of farm living was strongest for younger children. Those who moved to a farm after the age of five tended to have slightly higher rates of asthma.

The reasons for lower rates of asthma among farm-raised children aren't known. However, investigators found several factors that may play a role in asthma risk. Children living on a farm tended to have more siblings, were more likely to be breast-fed, were more likely to have outdoor pets, and were less likely to attend daycare. Researchers say these factors may influence the child's developing immune system to make them less susceptible to asthma.

Investigators are now beginning another study to look for clues about the nature of asthma risk factors. The Rural Childhood Asthma Morbidity Study is looking for rural families with children between one and 18 who have asthma or symptoms suggestive of asthma. Researchers are hopeful that once the study is completed, they will have some answers about how farm living may decrease the risk of developing childhood asthma. For information about the study, visit the website at http://www.mcw.edu/display/router.asp?DocID=9196.

SOURCES

National Heart, Lung and Blood Institute, http://www.nhlbi.nih.gov