Peanut Perils

Answers About a Dangerous Allergy

By Kathy Seale

0810_peanutIt’s a sign of the times: Across America, the entrances to many elementary-school classrooms are now guarded by the image of a large peanut trapped behind the red circle and slash that is the international symbol for “NO.”

Potentially deadly allergic reactions to peanuts have become a serious issue at schools, birthday parties, and anywhere else children and food mix in uncertain ways. And according to a heavily publicized study in the May 12 issue of the Journal of Allergy and Clinical Immunology, the problem is getting worse. Based on a 5,300-household survey, the study reported that the number of peanut allergies more than tripled over 10 years, from 0.4 percent of children surveyed in 1997 to 1.4 percent of children surveyed in 2008.

Extrapolating those findings nationwide is problematic, says UAB pediatric allergist and immunologist Prescott Atkinson, M.D.  But the number of confirmed cases of peanut allergy in the United States is trending upward, he agrees.

Spoiling for a Fight

Peanut allergy occurs when the immune system mistakenly identifies peanut proteins as harmful and responds by releasing histamine and other symptom-causing chemicals.

The antibody behind the allergic reaction is called Immunoglobulin E, or IgE. People who are allergic to peanuts tend to have a higher than normal level of IgE in their bloodstreams. (IgE antibodies are specific to individual allergens; IgE associated with peanut allergy, for example, is called peanut-specific IgE.)

It’s likely, Atkinson says, that the IgE system developed primarily to battle parasitic infections. And since the Western world has largely eradicated parasites, the system could be underutilized. “It’s looking for something to do,” Atkinson says. “And like a small child with too much time on its hands, the idle IgE system sometimes gets into trouble, producing antibodies against harmless substances.”

Changes in the environment, including dietary habits, could play a role in the increased numbers of peanut allergies, too. “If you eat anything that comes in a plastic wrapper, it will have a large array of ingredients,” Atkinson says—and that increases the chances of provoking an allergic reaction. “Years ago, our diets weren’t as varied.”

Without a Trace

There is no debate, though, about the seriousness of peanut allergy. Symptoms, which usually occur within minutes of exposure, include hives, swelling of the tongue, itching of the mouth and throat, tightening of the chest, nasal congestion, vomiting, diarrhea, and wheezing. For highly allergic children and adults, even a tiny amount of the food can create a life-threatening medical emergency called anaphylaxis, with symptoms that include a sudden drop in blood pressure, rapid pulse, restricted airways, and loss of consciousness.

“It’s a scary problem,” Atkinson says. Peanut allergy tends to show up between ages one and two, he notes. Risk factors include a family history of allergies, allergies to other substances, or atopic dermatitis (eczema).

The most serious risk factor for life-threatening peanut allergy-related anaphylaxis is allergic asthma, which many people with peanut allergies tend to have, Atkinson says. The essential medicine for anaphylaxis is epinephrine, although IV fluids, bronchodilators, and steroids can be part of the treatment process, too.  Allergists prescribe self-injectable epinephrine for emergency use by patients with severe food allergies.

There are no shots or miraculous medicines currently available to treat peanut allergies. The only way to avoid an allergic reaction is to completely avoid the offending food—which is easier said than done, particularly when eating away from home.

“The cook may have decided to throw a few peanuts into the pan,” Atkinson says. But it doesn’t take even that much peanut presence to provoke a reaction. Cross-contamination, the use of a low grade of peanut oil cooking spray (highly refined peanut oils are safe)—even the re-use of a pan that formerly contained peanuts—can all pose a threat as well.

It’s often a permanent problem, too, because only 10 to 20 percent of peanut allergies tend to disappear with age, Atkinson says. Whether an allergy resolves could depend on the level of IgE in the bloodstream. “Some data suggests that if the level of peanut-specific IgE is low at the time of diagnosis, that’s a good sign,” Atkinson says. “If early on you have high levels of IgE, it’s almost always a lifelong problem.”

On the Horizon

The allergist’s role in handling any problem is to test, monitor, and educate the patient, and finally if necessary to challenge the patient orally with the food to prove whether the allergy is still present, Atkinson says. Peanut allergies are rarely challenged unless the specific IgE has dropped to low levels, though, because reactions can be so severe. But there are “bright spots on the horizon,” Atkinson says. Desensitization treatments are being developed that aim to train the body to grow accustomed to peanuts through regular exposure to the food. Before they are ready for widespread use, though, “we need a technique that’s reliable and safe,” Atkinson notes. “We’re talking about initial exposure that’s way less than a single peanut.”

Another source of hope involves research to see if high-tech drugs like omalizumab, a monoclonal antibody approved for allergic asthma, could help peanut allergy sufferers, too.  Atkinson is optimistic: “I don’t have much doubt that in the next five or 10 years there will be an effective treatment for food allergies,” he says.

 

More Information

UAB Division of Pulmonary, Allergy & Critical Care