Allergies in Kids

More and more children in the US are developing allergies, and their close cousin asthma.  While some allergies are inconvenient and unpleasant, others are actually life-threatening, as asthma can also be, but so far, no one has been able to come up with an explanation for why we're seeing this increase.  This week on PodMed, Rick and I discuss an intriguing study in JAMA Pediatrics that adds one more piece to the puzzle in sorting this out.

Data from the National Survey of Children's Health including almost 92,000 participants from households with one or more children younger than 18 years of age was crunched.  One child from each household was randomly selected and parental interviews were conducted.  The data set was weighted to be representative of all noninstitutionalized children younger than 18 years of age nationally.

Asthma history, and the presence of atopic dermatitis or eczema, hay fever, and food allergy were queried. The child's birthplace was recorded as were parental birthplaces. For children born outside the US the length of time they were resident domestically was determined.

One in five children born outside the United States had any history of allergic disease, while almost 35% of those children born domestically did.  Children whose parents were born outside the United States had a lower risk of developing allergic disease: 18.2% versus 33.4%.   Most interesting of all, at least to me and Rick, is the fact that when children immigrate to the US their risk of developing allergic disease remains lower at 1-2 years post-arrival, but after 10 years their risk of any allergic condition is the same as those children born domestically. Well.  Does this mean that when children are resident abroad they are exposed to more allergens that direct their immune systems in such a way that garden variety molds, grasses and the like are simply too inconsequential to respond to? This would be  in support of the so-called 'hygiene hypothesis,' wherein exposure to parasites and other stimuli to the immune system effectively prevents said system from responding to other, possibly molecularly similar antigens but which don't really represent a threat.  In further support of this idea, we recollect on PodMed, is a study we covered a couple of years ago where children exposed early on to cats and dogs developed fewer allergies and asthma later in life, and yet another examining allergic diseases among those raised on farms, with similar results.  As I opine in the podcast, new parents might perhaps take this to heart and adopt one of the multitude of animals in shelters if they're not pet owners already.

There is an alternative explanation to migration to the US and subsequent development of allergies in kids, and that's the possibility that domestically, children are exposed to something not found in such high density elsewhere in the world that then gives rise to allergic conditions.  Fast food? SUVs? A preoccupation with perfect dentition? The possibilities are endless but also worth considering.  For now, if this provides more possibilities for an explanation that would no doubt benefit the legions of allergy sufferers everywhere.

Other topics this week on PodMed include HIV screening guidelines in Annals of Internal Medicine, and two from NEJM: whether surgery helps for cartilage tears in the knee, and a common antibiotic and cardiovascular risk. Until next week, y'all live well.

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Allergies in Kids | jhublogs
May 6, 2013 at 12:17 pm

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NUNAVUT CULTURE August 27, 2013 at 1:17 am

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