RENEE MONTAGNE, HOST:
And another health problem on the rise - allergies, especially in children. Nearly half of all children are now allergic to something, whether it's food, animals or plants. NPR's Patti Neighmond has that story.
PATTI NEIGHMOND, BYLINE: Dr. Andy Nish is in private practice in Gainesville, Georgia. Today he's seeing 16-year-old Casey, who's here for a routine check-up.
DR. ANDY NISH: So ears look good. Open mouth real big, say ahh.
NISH: OK. Good.
NEIGHMOND: Nish is looking for telltale signs of allergy - runny nose, itchy, watery eyes, sneezing. Casey's nose is a bit congested but it's not too bad.
NISH: All righty. Don't feel any lymph nodes in your neck. That's good. Take a listen to your breathing - big breaths.
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NEIGHMOND: Casey's allergic to dust, mites, cats, certain grasses and certain weeds.
NISH: He definitely has the three main, what we call atopic diseases, which would be allergic rhinitis or hay fever, asthma. And then he had more eczema when he was younger. And now he has more dry skin and these little bumps called keratosis pilaris. So, yes, he's definitely an example of somebody who is allergic.
NEIGHMOND: If you're allergic to one thing, chances are you're allergic to a number of things. Federal health officials say the rate of allergies among children in the U.S. today is two to five times higher than it was 30 years ago. Researchers are trying to understand why. The leading theory: the hygiene hypothesis.
NISH: It looks like with our modern living conditions and cleanliness that we have fewer and fewer germs to fight off.
NEIGHMOND: Which means our immune system doesn't get trained to recognize and fight foreign invaders, whether they're harmless or not. The theory is bolstered by evidence from farms. Studies show children who live on farms have low rates of allergies.
Dr. Mark Holbreich is an allergist in Indianapolis and a fellow of the American Academy of Allergy, Asthma and Immunology.
DR. MARK HOLBREICH: The farm effect is the fact that children seem to live on traditional farms have a lower prevalence of allergic diseases such as asthma and allergies.
NEIGHMOND: Holbreich recently did a study which found very low rates of allergies among Amish children living on farms in Indiana. He says the children may be protected because they get exposed early on to dirty environments and variety of dust and germs.
HOLBREICH: Actually when the mother's pregnant with the child and living working on the farm, working in the barn, drinking raw milk and then once the child is born on Amish farms, the children are very often at barn at young age, and when they're weaned from the breast, then they start drinking raw milk. And we think that there's something about unpasteurized and un-homogenized milk that is the key, along with exposure to large animals, particularly cows.
NEIGHMOND: Scientists don't know exactly what it is in raw milk, or in the barn, or on the cows that may boost the immune system. They're researching that now. But Holbreich cautions against drinking raw milk or serving it to your child. He says it contains far too many disease-causing bacteria.
There are other theories about why allergies are on the rise. Taking antibiotics early in life may be a factor. Tightly constructed homes with little ventilation may foster allergies. And today people stay inside for longer periods of time, not exposing themselves to the great outdoors.
But if you have allergies, Dr. Andy Nish says, you shouldn't despair.
NISH: There's good treatment out there and there's no need to suffer.
NEIGHMOND: There are lots of medications to treat symptoms of effectively. Antibiotics are commonly prescribed. There are over-the-counter anti-histamines and decongestants. And there's a nasal steroid sprays.
NISH: They help to decrease inflammation in your nose and they work over time so should be taken daily.
NEIGHMOND: But the closest thing to a cure, says Nish, allergy shots, injections of the actual allergic substance.
NISH: And so the allergy shots are to specifically to what that person is allergic and they're given in very small doses to - if you will - sneak it past the immune system.
NEIGHMOND: And slowly build up the body's tolerance. After a few months, allergies are usually under control. And after a few years, patients can usually stop the shots altogether.
Patti Neighmond, NPR News.
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