"It enhances inherited allergic tendencies and heightens the inevitability, in children so predisposed, of the atopic march--defined as a collection of conditions, events, and characteristics that set the stage for development of permanent allergic disorders.
"The atopic march begins in infancy and persists into adulthood. Asthma is frequently associated with this allergic progression."
Certain vaccines counterproductive
Dr. Hullon goes on to say that the people of highly developed and industrialized countries have more allergies and asthma than the less-developed countries and that in the developed countries the poorer people tend to have more asthma and allergies than do the more prosperous.
Dr. Hullon continued: "Studies correlating the prevalence of asthma in developed countries with increases in mass immunization suggest that certain vaccines heighten allergic susceptibilities.
"There is evidence, for example, that pertussis vaccine given to prevent whooping cough makes people more sensitive to histamines."
The list of autoimmune diseases in the United States and other highly developed countries is astounding. Here are some of them: Grave's disease, Addison's disease, multiple sclerosis, rheumatoid arthritis, systemic lupus and celiac disease.
Why are these disorders on the upswing? Some scientists have named a surprising culprit: cleanliness.
During the 20th century, life in the U.S.A. and other developed countries has become increasingly sanitized. Our water is cleaner, our food is refrigerated to keep bacteria from growing on it, and we are vaccinated against many diseases and germs.
We are exposed to far fewer bacteria, fungi, worms and other microorganisms than our ancestors were.
We read warnings about using a woodcutting board because it may have bacteria on it. We don't want to get our hands in the dirt, and it is considered a sign of prosperity to have others do our dirty work for us.
By contrast, people who live in underdeveloped countries live with a lot more dirt and germs.
Surprisingly, these people have fewer diseases involving an overactive immune system.
So some researchers have begun to wonder whether a lack of exposure to microbes might be making people sick.
Joel Weinstock, a professor of medicine at the University of Iowa, wrote: "We just assume that the cleaner you are the better off you are. Is hygiene really healthy?"
Dr. Weinstock is a proponent of the "hygiene hypothesis." It says that exposure to certain microbes is good for the human body.
Germs can make you stronger
According to this theory, germs train the immune system and keep it in shape. When the immune system doesn't get much of a workout from microbes, it may find another way to stay active.
"The immune system may turn against the body," said Athos Bousvaros, a doctor at Children's Hospital in Boston.
Microbes are not all the same, however. Only certain ones appear to be good at teaching the immune system and training it.
Among the good teachers, Dr. Weinstock says, are worms called helminths, which live in the gut.
When helminths enter the body they prompt certain immune cells to secrete chemicals. Those chemicals work as the immune system's stop signs and traffic lights, keeping the body's immune system under control. Without these chemicals, Dr. Weinstock believes, the immune system is in trouble.
To test whether worms make a difference, the professor fed helminth eggs immersed in Gatorade to 30 patients with ulcerative colitis for three months. Nearly half the patients reported a major improvement in their symptoms.
In the second study 21 of 29 patients with Crohn's disease who were treated with helminth worms for six months went into remission, with symptoms disappearing.
Other studies show that parasitic worms offer protection against allergies and asthma. As you probably know, asthma is an allergic condition in which the immune system overreacts to substances in the environment such as pollen and dust mites, causing breathing difficulties.
Maria Yazdanbakhsh, a Dutch immunologist, gave 152 African schoolchildren worm medication. The result was that 29 of the kids developed an allergy to dust mites.
The worms seemed to help prevent the allergy.
Other studies have shown that infecting mice with helminth protects them against asthma and diabetes.
Worms are not the only organisms that promote the development of a healthy immune system. Scientists say bacteria play an important role too.
A group of researchers studying children in rural Austria, Germany and Switzerland found that the kids were less likely to have asthma, hay fever or an allergic skin disorder when their bed mattresses contained high levels of endotoxins.
An endotoxin is a substance contained in some bacteria. The results suggest that a child's exposure to some bacteria may help the immune system tolerate, rather than overreact to, such substances as pollen.
Another study has shown that certain bacteria can ward off allergic reactions in mice. Harmless bacteria called lactobacilli--contained in yogurt--have been used successfully to treat allergic skin diseases in infants and children.
For years I wondered why it is that antibiotics depress the immune system. Based on the hygiene theory, it appears that antibiotics kill out the good bacteria that help regulate and train the immune system. Without those bacteria the immune system is not enhanced and thus lowered.
Improving your immune system
Foods containing bacteria are important for the body's immune system. Yogurt, sauerkraut and other fermented or pickled vegetables help replenish good bacteria in the body.
Many and various types of mushrooms have a beneficial effect on the immune system.
Fresh air and moderate exercise improve the immune system.
Eating the cruciferous vegetables helps with the immune system.
Two to three pieces of fresh fruit daily improve your body's overall health, and some food supplements are helpful as well.
Degrees of clean
How clean is clean? No one knows for sure. Experts are saying that bathing daily with antibacterial soap is probably a bad idea. Human skin is meant to be covered with bacteria that help keep it healthy.
Practicing sensible hygiene is still important. Some microbes can make you sick. So it is prudent to wash your hands before preparing food or eating and after using the bathroom.
But the truth is that many bacteria are your good friends and live in and on your body in an ecology that is yours to preserve.
So would a little dirt hurt?