The reasons for sneezin’ this allergy season

Winter seems to have finally broken. Temperatures are becoming milder, the sun’s coming out and some plants are starting to bloom. However, the blooms are associated with allergic symptoms in those who are susceptible. While spring may be enjoyable for many, it can be much less so for allergy sufferers.

So, given that some of our readers are likely bracing themselves for allergy season, here’s are a few things to know about allergies and their treatments, along with some of their rarer manifestations.

Why are allergies even a thing?

Why do some people have allergies? Are they beneficial in some way? Do they convey some kind of survival advantage? It used to be thought that some allergies were a byproduct of the immune system’s preparedness to repel invaders like bacteria, viruses, parasites and others. Perhaps allergies were part of a hyper-vigilant immune response in some people, and that the results produced were unpleasant for the sufferers and basically useless.

Ruslan Medzhitov, of the discoverers of a very important biological component of cells, toll-like receptors, has a somewhat different take on allergies and has some interesting data to back his idea up. After working on allergies for decades, he looks at them somewhat differently.

He argues that allergies may in fact confer a survival advantage. They can, under certain circumstances, help the allergic individual survive what would kill his non-allergic counterpart. To support his findings, he’s bred some immune deficient mice who won’t be able to develop allergies. He’s allowing them to be exposed to toxins over time, the theory being that they will suffer noticeable tissue or organ damage that mice who can develop allergies won’t.

He discussed some of his (and others’) previous work on allergies, along with other areas of biology and immunology, here. It’s quite a read.
Allergies and their treatment

Typical allergy symptoms — the medial term being allergic rhinitis (AR) — include watery eyes, runny nose, sneezing, nasal and ocular itching. Estimates are that between 25-50 million Americans suffer from AR. It can keep a patient miserable for periods when the allergens are in high concentration. Some patients still suffer even when they take even the most advanced forms of antihistamines.

Allergy shots may provide relief by gradually desensitizing the patient to the allergen over time, but there are drawbacks. The first of which is time: The shots start off as weekly subcutaneous injections, so they require frequent trips to the doctor. Also, the shots aren’t cheap, and some people just really hate needles. Some so much that they’d rather suffer with their allergies, sneezing and wiping and wheezing.

Pollen, via Creative Commons

Pollen, via Creative Commons

Over the past several years, an oral medication has been developed that can do the same job as the injections. This form of treatment is called SLIT (sublingual immunotherapy). The pill is placed under the tongue daily and allowed to dissolve. It produces results similar to the allergy shots, without the frequent office visits and without the needles. The new medication is designed for those who suffer allergies to 5 different types of grass allergies. Other sublingual forms are undergoing development for allergies other than those caused by grasses. Oralair® has been used for several years in Europe and in other areas, and was just approved by the FDA for use in the USA this year — but it is likely not yet available in most US pharmacies. You can check out some of the research on SLIT here.

Could allergies be contagious?

Can you catch an allergy from someone else? Experience says no — you never picked up your grandmother’s allergy to rhubarb. You never got your sister’s allergy to ragweed. But there have been cases where a allergy has been transmitted, at least temporarily.

One such incident happened to a little girl who needed surgery. She needed to be transfused and got a few units of blood. As she was recovering, she ate some peanuts and had a severe allergic reaction. She had never had a peanut allergy before, but when she was discharged her parents were warned not to let her anywhere near peanuts, for fear that her allergy would be permanent.

A few months later, the little girl, having forgotten about her allergy, started munching on some peanuts. Her parents were terrified and were ready to take her to the emergency room for treatment when the reaction started. But it never did. The parents contacted her doctors. They were puzzled; she had clearly had a reaction to peanuts in the hospital, and allergies don’t just vanish.

When someone develops a food allergy, their immune system “sees” that particular food as foreign, something that could be dangerous. It produces a specific immunoglobulin, IgE (immunoglobulin E). The IgE circulates and attaches to mast cells and basophils, which are cells of the immune system scattered throughout the body. The next time the antigen (the particular food that the patient’s immune system has identified as a danger) is present, that antigen will bind to the IgE that was produced against it. That triggers the IgE to signal the attached cells to release chemicals, like histamine, that provoke an allergic reaction. This reaction can be mild to very severe. It can even cause life-threatening anaphylaxis (swelling of areas of the mouth and throat), closing off airways in the lungs causing difficulty breathing, hives, vomiting, rapid heart rate and more.

Intrigued, the doctors wondered if one of the blood donors had had a peanut allergy. If so, the anti-peanut IgE that he had circulating could have attackhed to the little girl’s cells and then she would have developed the same peanut allergy. They traced the units of blood that she had received back to their donors. One of the donors said that he did have a severe peanut allergy, so his IgE had temporarily caused allergic reactions for her. Temporary because over time, his IgE would degrade and no longer be attached to her mast cells or basophils. Since she wasn’t producing her own anti-peanut IgE, once his was gone she was no longer allergic.

So, under certain unusual circumstances, allergies can be contagious.

Unusual allergies

Did you ever hear a parent say something like, “I really have a hard time getting my son to take a bath, I swear he must be allergic to water.” They joke, but it’s sort of possible for someone to actually be allergic to water. At least, exposing the skin to water can for some individuals provoke an allergic reaction that produces skin lesions and intense itching. Having a skin reaction to some physical change has been noted before in susceptible individuals. Some will break out in hives if pressure is applied to the skin, others will develop it if they exercise. Some will develop it from exposure to cold, others from exposure to heat.

The condition is called aquagenic urticaria and it’s extremely rare. Only about a hundred cases have been described since it was first discovered in the 1960s. It is more common in females than males and may start around puberty (but can start at any age). The patient notices their child breaking out in hives almost immediately after having water contact with their skin (after a bath, shower, swimming, being caught in a rainstorm, etc.). Characteristic lesions, wheals, quickly develop accompanied by very intense itching.

The lesions and itching usually also resolve reasonably quickly, even without a specific treatment. But it is extremely uncomfortable for the time it persists. For some as-yet undetermined reason, often only the upper body (face, arms, trunk) is affected. Imagine being caught in a rainstorm and suddenly having your face, trunk and arms turn bright pink, have wheal formation and then begin to itch like crazy. Or how difficult it would be just to keep clean. Quickly washing a small part of your body, then dying it quickly in hopes of avoiding an allergic reaction.

Recently, a new case was discovered in Utah. The patient had her first reaction when she was 12 years old. She and her family went on vacation. When she went swimming in the hotel pool, she developed the typical skin lesions and itching. Doctors at that time thought that she was having a reaction to some chemical in the pool water, but she had the same reaction when swimming in a clear lake not too long after. After a little digging on the Internet, she and her family went to her dermatologist and gave him the information. The condition is so rare that even they had to do some research of their own before they decided to test and confirm that she had it.

There are several different theories as to how aquagenic urticaria develops. One is that water forms a complex with a molecule that these patients produce in their skins, and that complex — not the water itself — is what the patient is allergic to. Another is that movement of something from a deeper layer of the skin towards the surface, that only occurs with the application of water, triggers the reaction. But researchers can do no more than speculate as to why it’s more prevalent in girls and most often develops during puberty. It’s difficult to study a disease when such a small number of people are affected.

The good news is that there are some effective treatments that may help to control the condition. For example, Fexofenadine (Allegra®), a third-generation antihistamine, can work for some patients. Patients can be put on daily doses of these medications to help prevent reactions. So even if your kid really is allergic to water, they still have no excuse.

Mark Thoma, MD, is a physician who did his residency in internal medicine. Mark has a long history of social activism, and was an early technogeek, and science junkie, after evolving through his nerd phase. Favorite quote: “The most exciting phrase to hear in science... is not 'Eureka!' (I found it!) but 'That's funny.'” - Isaac Asimov

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