May is National Asthma and Allergy Awareness Month and according to recent statistics, childhood allergies and asthma are on the rise. One leading hypothesis that seeks to explain the growing numbers might surprise you: The “hygiene hypothesis” suggests the increase may be a byproduct of being too clean.

First proposed in 1989, the hypothesis continues to pick up steam among researchers and physicians alike, including Dr. Matthew C. Bell, assistant professor of pediatrics and internal medicine in the Division of Allergy and Immunology at Arkansas Children’s Hospital and University of Arkansas for Medical Science (UAMS).

“As a population, we’re a ton cleaner than other generations,” Bell says. “You look at kids on the farm who are around animals and there’s something in that exposure that causes them to push away allergies. Of course, I’m not talking about good hygiene like washing your hands after you go to the bathroom. But there’s growing evidence that this has something to do with the rise in allergies.” Dr. Kelly Burks of the Arkansas Allergy and Asthma Clinic in Little Rock agrees: “Kids don’t play in the dirt anymore. Kids don’t live on farms as much anymore and there’s some evidence that this is preventing immune systems from developing fully,” she says.

John Hopkins University immunogeneticist Kathleen Barnes’ work on the genetic causes of asthma, cited in a 2013 Washington Post article, suggested a steadily declining exposure to germs may have a causal effect on asthma rates, even though it’s a genetic condition. The article cited another study comparing Amish and Swiss farm and non-farm children, released in 2012, that revealed the farmers had significantly lower rates of asthma, hay fever and eczema despite daily exposure to animals, dust and plant pollens.

Whatever’s at its root, allergy rates are steadily climbing. Statistics from the Allergy and Asthma Network Mothers of Asthmatics report nearly 10 million children have skin allergies, 6.7 million suffer from hay fever and roughly 4.1 million have food allergies. What makes this trend particularly unnerving for parents is that there isn’t a strong hereditary link with allergies, particularly food allergies. This means the first time a parent discovers their child’s peanut, bee sting or pollen allergy is likely right after first contact with the allergen.

Dr. Bell says while debate in the medical community is ongoing over the usefulness of panel testing very young kids, he views that measure as excessive. Instead, he suggests parents watch for reactions such as hives, swelling of lips or trouble breathing. “For food allergies, the prime ages are between 1 and 3,” Dr. Bell says. “At this age, table food is being introduced. And since there is no peanut baby food, they probably aren’t being exposed to that until after age 1.”

Asthma, on the other hand, has a very strong hereditary component. While asthma is not an allergy, internal asthma attacks are triggered by allergic reactions such as to dust mites, mold or pet dander. Non-allergic (extrinsic) asthma is triggered by something other than allergens, like cold air, stress or exercise. Hygiene hypothesis aside, much is unknown about what causes asthma. Like allergies, asthma cases are rising. Between 2001 and 2011, Americans with asthma increased from 7.3 percent to 8.6 percent or just under 26 million people, 7 million under the age of 18. Asthma can develop at any age, but it is rare in children under 5 says Dr. Burks.

“Asthma usually doesn’t show up at birth, and the age when it does show up varies” she says. “More common are viral illnesses such as bronchiolitis which in adults would be just a bad cold, but in kids under 3 can be serious, even life-threatening.”

Dr. Burks says babies and toddlers breathe heavily or cough for any number of innocuous reasons, but wheezing or labored breathing is something worth getting checked out. Environment plays a big part in respiratory health, so pay attention to frequency of dusting, exposure to pets, strong chemical smells or cigarette smoke. “Cigarettes themselves aren’t an allergen, but are what’s known as an irritant, which can trigger an attack,” says Dr. Burks.

Obviously, children’s ability to articulate is limited at this age, as is a parent’s ability to recognize the difference between temporary illness and chronic disease. While cautioning against over-reacting, Dr. Burks offers two important rules of thumb. “Number one, don’t overlook coughing at night,” she says. “Second is coughing when playing. If a child cannot sleep all night or play normally without problems breathing or coughing, that’s something to get checked out.”

Resources

There’s a wealth of information and resources available online for parents of children with allergies. These recommended sites include helpful explanations of common conditions as well as information on diagnosis and treatment.