Researchers who once called for avoidance are now exploring early exposure to prevent allergies.

Peanuts, pollen, dust and dairy.

When it comes to allergies, they're among the worst offenders, making millions miserable, non-productive—and in some cases—dangerously ill.

Allergies are on the rise, affecting as many as 30 percent of adults and 40 percent of children in the United States, according to the Asthma and Allergy Foundation of America. The prevalence of peanut allergies alone has doubled in the past 10 years among children in Western countries, studies have shown.

Tempering that trend are important advances in the treatment and potential prevention of allergies.

Why the increase in allergies? Experts have many theories but few hard facts. The most prevailing hypothesis has to do with hygiene—in Western societies; children's immune systems are exposed to far fewer bacteria and other organisms, which modifies their response. An allergic reaction essentially is an immune response to the body's perceived threat of attack from foreign objects.

“We train our immune systems how to respond,” says Dr. Princess Ogbogu, division director of Allergy and Immunology in the Department of Otolaryngology at Ohio State University Wexner Medical Center.

Before the dawn of modern medicine and still today in underdeveloped countries, immune systems were exposed to such deadly threats as parasitic disease, malaria and whooping cough. In Western countries, our immune systems aren't working that hard.

Immune cells known as T cells are primarily responsible. In healthier society, T cells adapt to target less obviously threatening substances, such as cat dander or ragweed, says Dr. Summit Shah, an allergist with Premier Allergy.

“It's almost as if our immune systems become bored” and therefore seek new targets, Ogbogu says.

Still, she and others agree—allergic disease is nothing to, well, sneeze at.

“This really impacts people's quality of life and is one of the leading causes of healthcare costs,” Shah says.

In the case of pollen allergies, Ogbogu says central Ohioans were particularly hard hit this year because of a mild winter with many fluctuations. “We didn't have a prolonged freeze, which can cause plants to ‘super pollinate,'” she explains.

When it comes to treating allergies, immunotherapy has been the standard for decades. It involves exposing patients to incrementally increasing doses of an allergen in order to de-sensitize and re-train their immune systems, and thereby reduce allergic reactions.

A huge shift now is occurring in the way physicians approach some allergies—namely, peanuts.

It's been standard practice for physicians to urge avoidance of peanuts, eggs and milk in at-risk children the first three to five years of life.

However, the landmark Learning Early About Peanut Allergy (LEAP) study found that introducing peanut protein to babies at four to seven months significantly reduced the rate at which they developed allergies.

“This is exciting, potentially game-changing research,” Ogbogu says. “There actually is some thinking that maybe we in the medical community unknowingly may have been contributing to the problem by preaching avoidance.”

The American Academy of Pediatrics issued new guidelines last year recommending that at-risk infants be exposed to peanut protein at about four to six months of age. “It's a complete switch in mindset,” says Dr. David Stukus, associate professor in the Division of Allergy and Immunology at Nationwide Children's Hospital.

“We're now looking at the idea that we might be able to prevent thousands of cases from occurring in the first place,” Stukus says.

Researchers are studying how much peanut protein children must consume to stay protected, and for how long.

In similar research on other food triggers, Stukus says data have looked “very positive” for eggs, while results for milk have been mixed.

Stukus says allergies have a disproportionate effect on urban, inner-city populations, due in part to environmental factors such as dust mites and cockroaches. “We see these kids really suffer. It impacts their lives on a daily basis, and it can affect learning and school performance.”

Allergic reactions can range from relatively mild—sneezing, watery eyes and itching—to serious, such as anaphylaxis, which can be fatal.

As the medical community learns more about the exact nature of allergies, patients now may have additional options for confronting the problem, including:

Oral administration of allergens in immunotherapy, including for food allergies Patches that slowly deliver allergen doses through the skin. The so-called “peanut patch” is currently being studied in clinical trials, including one in Cincinnati. “Rush” immunotherapy, where patients receive several injections during one visit, reducing total overall treatment time. Using immunotherapy to allow patients to tolerate certain medications, such as penicillin. Patients are given antihistimine medications beforehand and are closely monitored after.

Also on the horizon is targeted immunotherapy using biologic agents to wage a far more precise attack on allergies.

A drug like prednisone, for example, is effective at reducing inflammation but comes with significant side effects, Stukus says. “It's like putting out the fire. We're trying to extinguish the match. A combination of genetic information and biologic markers will allow us to get very specific.”

Local experts look forward to being able to offer their patients more choices in allergy treatment, as well as the possibility of preventing allergies altogether. For some allergies, Ogbogu says, “All we've had until now is strict avoidance and carry an EpiPen.”

Laurie Allen is a freelance writer.

Misery Makers

A list of some of the most common allergens:

Cat and dog dander Dust mites Food Pollen (tree, grass, weed)

THE BIG 8

Peanuts Tree nuts Eggs Milk Shellfish Fish Soy Wheat

Note: People often outgrow food allergies, with the exception of nuts and seafood.

Allergies Take Their Toll

Allergic disease, including asthma, is the fifth-leading chronic disease in the United States; among children under 18, it is the third most common. Americans lose more than six million work and school days and make more than 16 million visits to their doctors annually because of allergies and asthma. Food allergies cost about $25 billion each year.

Source: Asthma and Allergy Foundation of America