Bugging Asthma

By Christine Gorman

It's called the "Hygiene Hypothesis," and researchers invoke it to try to explain why the number of children who develop asthma has grown so dramatically over the past three decades. Bolstered by a handful of studies, the basic idea is that modern urban society is too clean for the kids' own good. A hundred years ago, children's immune systems would have faced all kinds of bacterial and viral infections. Today those immune systems don't know what to do in our supersanitized environment, so they wind up attacking pollen, dust mites and other usually innocuous substances instead. In the worst cases, a dangerous overreaction occurs that can shut down the lungs, killing the child.

Now comes word of more evidence for the anticleanliness argument. In a study involving more than 1,000 children, published in last week's New England Journal of Medicine, researchers at the University of Arizona compared youngsters who had attended day care before the age of six months with those who had enrolled at a later date. As you might expect, the younger kids, who were exposed to other children earlier and more often, experienced more infections and wheezing. But after they turned six years old, their risk of asthma was less than half that of the children who had enrolled in day care after they were six months old. The researchers' cautious conclusion, according to co-author Anne Wright: "More infectious disease early in life might afford a lifetime protection."

But before you decide to plop your baby next to every runny-nosed kid in sight, there are a few things you should know. Finding an association does not prove a cause-and-effect relationship. Furthermore, some infections can by themselves be quite harmful, even life threatening. The last thing any doctor would suggest is that outbreaks of, say, meningitis or diphtheria are good because in the long run they might protect the survivors against asthma.

Yet even if the association between early infections and a reduced risk of asthma turns out to be real, you can't use it as a basis for healing kids afflicted with asthma. Their immune systems have already made a fundamental shift into asthmatic overdrive. Uncontrolled exposure would only make them sicker. Similarly, the Arizona findings would not apply to babies who are born prematurely and are thus more vulnerable to infections than full-term babies.

Although researchers are still pondering what's behind the alarming increase in asthma, there are plenty of things that parents can do to help allergy-prone or asthmatic kids. For example, many allergists find that giving children a series of shots containing varying amounts of carefully selected irritants can desensitize the immune system and get it back on a more normal track. (The injections don't generally trigger an overreaction because they are delivered not into the respiratory system but through the skin.) "The shots usually aren't given before age 4," says Dr. Ira Finegold of St. Lukes-Roosevelt Medical Center in New York City. "But it can be done earlier."

There are also medications that can stop asthma attacks as they occur, as well as still other drugs that help prevent future ones from happening. But for all the advances in treatment, asthma is still something of a mystery. Even so, if you take advantage of what is known, you may help save your child's life.

For more on asthma, visit www.aaaai.org www.allergy.mcg.edu or time.com/personal E-mail Christine at [email protected]