Asthma on the Rise in the U.S.

PHILLIP BOURJAILY / ENN 20sep00

Seventeen million Americans suffer the debilitating effects of asthma, and their wheezing, breathlessness and coughing fits cost us more than 100 million sick days each year. Alarmingly, asthma has shown a dramatic rise in the United States in recent years, leading Surgeon General David Satcher to remark, "We're moving in the wrong direction, especially among minority children in urban communities."

Between 1980 and 1994, reported cases of asthma jumped 75 percent in the United States. Researchers remain unsure of the causes of the increase. One intriguing new theory suggests we might be too clean for our own good.

The idea seems to run counter to the conventional view of asthma, which holds the condition is an allergic reaction to irritants such as smoke, dust mites, pollution, cockroaches and pet dander. Children in poorer urban areas often live in crowded homes with poor ventilation and water damage; ideal conditions for cockroaches and dustmites.

Some researchers now posit that while such conditions trigger asthma attacks, they do not cause the condition. Instead, the scientists suspect modern hygiene practices and antibiotics may actually prevent infant's immune systems from developing properly.

The immune systems asthmatics seem unable to differentiate between life-threatening microbe invasions and mere irritants, and they overreact to dust or pets. Some researchers hypothesize that growing up among the dirt and livestock of a farmyard helps young immune systems develop properly.

Fernando Martinez of the University of Arizona is one of the leading proponents of this theory. "Just as you need to use your eyes to develop your sight, and legs to develop the muscles to walk, your immune system develops through its experience," he says.

Researchers point to a strange pattern of increases in asthma around the world. Asthma, it seems, primarily afflicts citizens of developed, "modern" nations. Asthma has increased in the United States, Sweden, Australia and New Zealand, yet there has not been a corresponding rise in asthma in such undeveloped parts of the world as China and sub-Saharan Africa. The sooty, polluted former East Germany, for example, actually shows much lower asthma rates than cleaner West Germany.

One intriguing asthma study has centered on a Hutterite farm colony in South Dakota. Hutterites are a religious sect from the Tyrolean Alps who settled in the Dakotas and Canada in the 19th century. They are farmers who live communally in farm compounds.

Although the Hutterites show a high genetic predisposition to asthma, yet the symptoms asthmatic Hutterites show are so mild their asthma often goes undiagnosed and requires no treatment. Researchers theorize that children growing up near the dirt and livestock found in a Hutterite compound are exposed to microbes that allow their immune systems to develop.

Allergists studying children living on small farms in Austria, Bavaria and Switzerland (where the Hutterites originally lived) found that children who grow up drinking raw milk and living close to stables have 75 percent fewer allergies than children raised in nearby villages. There's a strong correlation between asthma and allergies; 90 percent of asthmatic children suffer from allergies.

Children in the developed world are protected from germs with vaccines and antibiotics to a much greater degree than children in developing countries. At the same time, children in the United States and other countries with a high rate of asthma are insulated from agrarian dirt and microbes.

No one is recommending that we stop inoculating children against deadlier diseases nor turn our backyards into barnyards. Yet, as Scott Weiss of Harvard's Channing Laboratory suggests, "There may be some optimal timing when exposure to infection should occur ... but we're preventing children from getting that exposure."