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Dr. Dejarnett, who is board certified in internal medicine and in allergy and immunology, practices at 464 North Parkway, Suite D.

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Solving the riddle why allergies are increasing

Dr. Alan DeJarnatt examines a patient.

From pollen to peanuts, from dust mites to dairy products, Dr. Alan DeJarnatt sees an ever-growing number of things to which people are allergic. The board-certified allergist also is seeing an increase in the number of patients with allergies.

As he treats his patients to lessen the effects of their allergies, he faces a riddle that a lot of researchers are trying to solve: Why is the prevalence of allergy increasing?

"We still have a lot of unanswered questions about allergies," he says. As we look for solutions, he adds, we need to be careful about drawing hasty conclusions.

We do know that an allergy is a genetic disorder — the ability in some of us to create allergic antibodies to foods, objects in the air and other allergens, he says. "We also understand that why a person develops these allergic antibodies is more than the genes we inherit."

Here are some of the aspects of the allergy riddle…

Genes: If your mom, for example, has an allergy to peanuts, you could inherit the gene to create allergic antibodies, but it may not be to peanuts. Your allergy could be a totally different allergen. "People may withhold certain foods from their children because they have an allergy to a food and they think their children will, too," Dr. DeJarnatt explains. "You can't make that association, however."

More on genes: While a child is developing as an embryo and in the early years of life, his genes are more susceptible to environmental factors that could play a role later on with allergies. "Our old assumptions about food exposures are a lot more complicated than we thought," he says. "It's not just about withholding foods."

Viruses, etc.: Exposure to certain infectious agents, such as viruses, could play a co-role in allergies. "Researchers suspect this, but we still don't understand what role they play."

Medications: Another co-factor could be medications, Dr. DeJarnatt says. Taking acetaminophen, both while the mother is pregnant or in a baby's early life, could be a factor in allergies. "Researchers are still trying to understand that mechanism. Meanwhile, though, parents shouldn't overreact. When a child has a high fever, parents should still reach for the baby Tylenol."

Environment: The general environment also can be a factor. "We live in a much more sterile world and have become more urbanized," he says. "Our homes are tighter, more insulated. It's called the hygiene hypothesis." Farm kids, who are exposed more to dirt and the natural environment, tend to have fewer allergies. As another example, two generations ago, most homes had hardwood floors. Today, most homes have carpeting. "We know that carpeted and insulated homes have more dust mites," he says.

"We are changing the interface our immune system has to the outside world."

Pollutants: Pollutants in our environment — combustion, plastics and sulphur dioxide — also are being investigated about whether they are a cause for an increase in allergies.

Changing allergens: Another factor is whether the allergens themselves have mutated and changed. For example, have dust mites changed so that we are more likely to have an allergy to them? With the hybridized growing of peanuts, are the peanut proteins more capable of triggering sensitivity than they used to be?

"None of these things are the simple answer, and none of these associations are well understood yet," Dr. DeJarnatt says. "Some may sound scary, but as we look for the answers to our riddle, we can't overlook the positives these things have brought into our lives."

As researchers work to solve the riddles surrounding allergies, physicians like Dr. DeJarnatt find themselves treating more patients with allergies. Treatment options include limiting the exposure to the allergen, treating the effects of the exposure and using immunotherapy, which desensitizes the allergic reaction.

"Most patients can be treated and can get better," he says. That's one reason why he chose his specialty. Besides being so interesting, he adds, "it is also very rewarding to see patients get better."