No, the term ‘allergic march’ is not an observance of allergy awareness held in March (although given the suggestive pun, it might actually be a good idea). It’s a term that describes the switch from one form of allergic manifestation to the next.
Skin allergy, food allergy, allergic rhinitis – the word ‘allergy’ seems to be associated with many conditions. Are they linked by the same underlying pathology? Is it right to say they belong in a continuum, or are they better off segregated in different baskets like apples and oranges?
That’s what the concept of the allergic march hopes to answer.
Food allergies, atopic dermatitis, allergic rhinitis, and asthma all belong to the same allergy umbrella. The allergic march depicts the natural history of allergies throughout a person’s life. For instance, you may have had atopic dermatitis. As a teen, you become allergic to eggs. Then, as an adult, you start developing allergic rhinitis.
However, predicting the evolution of allergy from one diagnosis to another is difficult, given the complicated nature of atopy. For instance, although allergies during childhood may point to the possibility of developing asthma in the future, it remains that: a possibility, not a certainty.
Case in point: Wheezing between 10 and 11 years of age led to an increased risk for asthma in adult life, reported Helen Rhodes and her colleagues in a 2001 article published in The Journal of Allergy and Clinical Immunology. Oddly enough, wheezing in babies less than 2 years old did not lead to the same outcome.
The “march” from one form of allergy to another happens throughout life. In Rhodes’ study, atopic dermatitis peaked when babies turned one. They started showing signs of allergic rhinitis, with its incidence continuing to increase, as they grew up.
Wheezing was then reported in almost one out of every two participants when they turned 22 years old. Food allergies reached a peak at about the same time.
A bigger study led by Susanne Lau, published 2002 in Paediatric Respiratory Reviews, also revealed a similar pattern.
Three-month-old babies suffering from atopic dermatitis reacted to inhalant allergens when they turned five. Half of all babies with atopic eczema and a family history of allergy also developed rhinitis or asthma at 5 years of age – that’s a considerable number, given how only about one out of every 10 babies without these risk factors developed rhinitis or asthma later in life.
Think of all four allergic entities as possible destinations, instead of as definite pit stops. Depending on your itinerary, you may visit one or perhaps all.
Potential destination #1: Atopic dermatitis
Among individuals with a predisposition to allergies, atopic dermatitis is usually the initial manifestation. It usually starts during the first year of life.
It is most prevalent before children turn three, according to the World Allergy Organization (WAO). This type of dermatitis manifests as a persistent itch and is described as “the itch that rashes”.
The pattern and appearance of dermatitis vary, depending on the person’s age. Among infants, for instance, the cheeks are usually affected. Extensor areas are more commonly affected among younger kids, with flexor areas getting more involved as they grow up.
In adults, dermatitis looks dark and thickened (lichenified).
Potential destination #2: Food allergy
Many believe that atopic dermatitis is a manifestation of food allergies – this is a misconception, explained Ulrich Wahn of WAO.
Severe cases of atopic dermatitis early in life do point to an increased incidence of food allergies. It must be said, however, that sensitization to food allergens is better seen as a “complication” of atopic dermatitis.
Although both entities are related, they are independent of each other: Atopic dermatitis is not a component of food allergy.
Destination #3: Allergic rhinitis
Can you imagine having a cold every so often? One episode is annoying enough, let alone many in a month.
That’s the kind of inconvenience that a person with allergic rhinitis has to endure. Manifestations include nose itching, sneezing, congestion of nasal passages, and/ or rhinorrhea (runny nose).
Adding to the problem is the therapy. One’s decision to medicate may be influenced by the drugs’ side effects, such as drowsiness.
Destination #4: Asthma
Last but not the least, asthma is a chronic condition that involves three pathologic processes: airway inflammation, bronchial hyperresponsiveness, and intermittent airflow obstruction.
Severe exacerbations (called “asthma attacks” by many) can cause death. Even people diagnosed with intermittent asthma – considered the least severe out of four “stages” – can still suffer from life-threatening exacerbations.
The allergic march begs the question, “How does it all start?”
Here’s what we know so far.
- It’s a mix of genes and the environment – According to Hugo Van Bever and his team in a 2008 article published in the WAO Journal, allergies cannot be exclusively blamed on either genes or the environment alone. It’s a complex interplay between both nurture and nature: One’s genetic makeup predisposes to the disease, with external factors adding to the risk or triggering an allergic episode.
- Having parents with asthma increases the allergy risk four-fold – Do your parents have asthma? If so, you’re four times more likely to get food allergies than someone whose parents never wheezed their entire lives, according to a John Warner in a 2004 article published in the Archives of Disease in Childhood. We are all arguably “primed” to react to allergens, with children of asthma sufferers much more so than others.
- Allergy or not, breastfeeding is best for babies – Cow’s milk and many other food allergens may increase your propensity to allergies, especially when given at an early age. Ah, breastfeeding really is best for babies.
- One’s pregnancy tells a story – Even before you were born, you were already at a risk for allergy – not only because of the genes you carry, but also because of your mother’s diet, her immune system, and many other factors that affected her pregnancy. Knowledge of these factors has helped experts come up with preventive measures, enumerated below.
Just because you are predisposed to allergies does not mean you are helpless! Early diagnosis, prevention, and treatment help change the story.
Here are some tips on prevention, backed by evidence.
- Breastfeed to prevent allergies in babies – Avoidance of milk formula for the first six months of life protects from – or at least delays the onset of – atopy, reported Noah Friedman and Robert Zieger in a 2005 article published in The Journal of Allergy and Clinical Immunology.
- Find at least two furry friends – Here’s some good news for people who have pets: There is no need to avoid the company of furry friends during pregnancy! If anything, exposure to considerable concentrations of cat allergen actually results in induced tolerance. The result: a baby protected from allergy to cat dander, according to Gennaro Liccardi and his team in a 2005 article published in Respiratory Medicine. This protection extends to other allergens, too. Children two years and below with at least two pets at home don’t easily develop allergies to pollen, for instance. Having a cat before age 18 also protects from adult asthma. Caveat: Medium-level exposure to cat allergen does result in allergies. If you already have one pet, adopt at least one more – a minimum of two pets helps to spell the difference between sensitization and tolerance.
- Keep your home free from pests – Cats and dogs may help prevent atopy, but other living things in your home may not be as beneficial. Dust mites, for instance, contribute to the development of the allergic march. The more dust mites there are, the more likely a person will develop allergies to them, according to Adnan Custovic and colleagues in a 2003 article published in The Journal of Allergy and Clinical Immunology. This dose-dependent relationship also applies to allergens from mice and cockroaches, as reported in a 2001 article by Karen Huss and her team, published in the same journal.
Marching to a different beat
A quick online search might lead you to different diagrams of the allergic march, showing you which allergic manifestation appears at what age.
Useful as such diagrams may be, they may be confused as a fixed timeline of how allergies develop in all people. That’s where misconceptions arise.
Aware that the term has led parents to believe that their children’s symptoms will “march” from relatively mild symptoms to much worse manifestations, Wahn explained that the term is not a reassurance that one’s allergies will worsen over time.
Here’s one more thing the allergic march isn’t: a definite progression from one form of allergy to the next. Nope, just because the allergic march diagram shows asthma as the final step doesn’t mean a child suffering from allergic rhinitis today will develop asthma in the future.
The allergic march simply helps to tell the grand story of atopy in a nutshell. The plot is expected to be different for all people, what with allergies being a gamut of conditions that show considerable variety.
Now that you know more about the allergic march, share what you learned with your loved ones. If there’s one thing everyone should be allergic to, it’s misinformation.